From patchwork Fri Jul 9 00:13:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472108 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78227C07E9C for ; Fri, 9 Jul 2021 00:14:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61F2E61469 for ; Fri, 9 Jul 2021 00:14:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229845AbhGIAQp (ORCPT ); Thu, 8 Jul 2021 20:16:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhGIAQo (ORCPT ); Thu, 8 Jul 2021 20:16:44 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40D3FC061574; Thu, 8 Jul 2021 17:14:02 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 3C9451F41516 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 01/11] futex2: Implement wait and wake functions Date: Thu, 8 Jul 2021 21:13:18 -0300 Message-Id: <20210709001328.329716-2-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Create a new set of futex syscalls known as futex2. This new interface is aimed to expand it with new functionalities without modifying the current complex interface. Implement wait and wake functions with support for 32 sized futexes: - futex_wait(void *uaddr, unsigned int val, unsigned int flags, struct timespec *timo) The user thread is put to sleep, waiting for a futex_wake() at uaddr, if the value at *uaddr is the same as val (otherwise, the syscall returns immediately with -EAGAIN). timo is an optional timeout value for the operation. Return 0 on success, error code otherwise. - futex_wake(void *uaddr, unsigned long nr_wake, unsigned int flags) Wake `nr_wake` threads waiting at uaddr. Return the number of woken threads on success, error code otherwise. ** The `flag` argument The flag is used to specify the size of the futex word (FUTEX_[8, 16, 32, 64]). It's mandatory to define one. By default, the timeout uses a monotonic clock, but can be used as a realtime one by using the FUTEX_REALTIME_CLOCK flag. By default, futexes are of the private type, that means that this user address will be accessed by threads that shares the same memory region. This allows for some internal optimizations, so they are faster. However, if the address needs to be shared with different processes (like using `mmap()` or `shm()`), they need to be defined as shared and the flag FUTEX_SHARED_FLAG is used to set that. By default, the operation has no NUMA-awareness, meaning that the user can't choose the memory node where the kernel side futex data will be stored. The user can choose the node where it wants to operate by setting the FUTEX_NUMA_FLAG and using the following structure (where X can be 8, 16, or 32, 64): struct futexX_numa { __uX value; __sX hint; }; This structure should be passed at the `void *uaddr` of futex functions. The address of the structure will be used to be waited/waken on, and the `value` will be compared to `val` as usual. The `hint` member is used to defined which node the futex will use. When waiting, the futex will be registered on a kernel-side table stored on that node; when waking, the futex will be searched for on that given table. That means that there's no redundancy between tables, and the wrong `hint` value will led to undesired behavior. Userspace is responsible for dealing with node migrations issues that may occur. `hint` can range from [0, MAX_NUMA_NODES], for specifying a node, or -1, to use the same node the current process is using. When not using FUTEX_NUMA_FLAG on a NUMA system, the futex will be stored on a global table on some node, defined at compilation time. ** The `timo` argument As per the Y2038 work done in the kernel, new interfaces shouldn't add timeout options known to be buggy. Given that, `timo` should be a 64bit timeout at all platforms, using an absolute timeout value. Signed-off-by: André Almeida --- arch/x86/entry/syscalls/syscall_32.tbl | 2 + arch/x86/entry/syscalls/syscall_64.tbl | 2 + include/linux/compat.h | 4 + include/linux/futex.h | 21 +++++ include/linux/syscalls.h | 6 ++ include/uapi/asm-generic/unistd.h | 7 +- include/uapi/linux/futex.h | 4 +- init/Kconfig | 7 ++ kernel/Makefile | 1 + kernel/futex.c | 23 +----- kernel/futex2.c | 103 +++++++++++++++++++++++++ kernel/sys_ni.c | 5 ++ 12 files changed, 163 insertions(+), 22 deletions(-) create mode 100644 kernel/futex2.c diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 4bbc267fb36b..e3b827a9c094 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -451,3 +451,5 @@ 444 i386 landlock_create_ruleset sys_landlock_create_ruleset 445 i386 landlock_add_rule sys_landlock_add_rule 446 i386 landlock_restrict_self sys_landlock_restrict_self +447 i386 futex_wait sys_futex_wait compat_sys_futex_wait +448 i386 futex_wake sys_futex_wake diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index ce18119ea0d0..63b447255df2 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -368,6 +368,8 @@ 444 common landlock_create_ruleset sys_landlock_create_ruleset 445 common landlock_add_rule sys_landlock_add_rule 446 common landlock_restrict_self sys_landlock_restrict_self +447 common futex_wait sys_futex_wait +448 common futex_wake sys_futex_wake # # Due to a historical design error, certain syscalls are numbered differently diff --git a/include/linux/compat.h b/include/linux/compat.h index 8855b1b702b2..5a910e0c437a 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -692,6 +692,10 @@ asmlinkage long compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, compat_size_t __user *len_ptr); +/* kernel/futex2.c */ +asmlinkage long compat_sys_futex_wait(void __user *uaddr, compat_u64 val, + unsigned int flags, + struct __kernel_timespec __user *timo); /* kernel/itimer.c */ asmlinkage long compat_sys_getitimer(int which, struct old_itimerval32 __user *it); diff --git a/include/linux/futex.h b/include/linux/futex.h index b70df27d7e85..f0eaa05ec8bc 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -77,6 +77,27 @@ void futex_exec_release(struct task_struct *tsk); long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, u32 __user *uaddr2, u32 val2, u32 val3); + +int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset); +int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, + u32 bitset); + +/* + * Futex flags used to encode options to functions and preserve them across + * restarts. + */ +#ifdef CONFIG_MMU +# define FLAGS_SHARED 0x01 +#else +/* + * NOMMU does not have per process address space. Let the compiler optimize + * code away. + */ +# define FLAGS_SHARED 0x00 +#endif +#define FLAGS_CLOCKRT 0x02 +#define FLAGS_HAS_TIMEOUT 0x04 + #else static inline void futex_init_task(struct task_struct *tsk) { } static inline void futex_exit_recursive(struct task_struct *tsk) { } diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 050511e8f1f8..b9c2874410d0 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -623,6 +623,12 @@ asmlinkage long sys_get_robust_list(int pid, asmlinkage long sys_set_robust_list(struct robust_list_head __user *head, size_t len); +/* kernel/futex2.c */ +asmlinkage long sys_futex_wait(void __user *uaddr, u64 val, unsigned int flags, + struct __kernel_timespec __user *timo); +asmlinkage long sys_futex_wake(void __user *uaddr, unsigned int nr_wake, + unsigned int flags); + /* kernel/hrtimer.c */ asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp, struct __kernel_timespec __user *rmtp); diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index d2a942086fcb..df9fe2e23ee0 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -872,8 +872,13 @@ __SYSCALL(__NR_landlock_add_rule, sys_landlock_add_rule) #define __NR_landlock_restrict_self 446 __SYSCALL(__NR_landlock_restrict_self, sys_landlock_restrict_self) +#define __NR_futex_wait 447 +__SC_COMP(__NR_futex_wait, sys_futex_wait, compat_sys_futex_wait) +#define __NR_futex_wake 448 +__SYSCALL(__NR_futex_wake, sys_futex_wake) + #undef __NR_syscalls -#define __NR_syscalls 447 +#define __NR_syscalls 449 /* * 32 bit systems traditionally used different diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h index 235e5b2facaa..44750caa261e 100644 --- a/include/uapi/linux/futex.h +++ b/include/uapi/linux/futex.h @@ -42,7 +42,9 @@ FUTEX_PRIVATE_FLAG) #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ FUTEX_PRIVATE_FLAG) - +#define FUTEX_32 2 +#define FUTEX_SHARED_FLAG 8 +#define FUTEX_SIZE_MASK 0x3 /* * Support for robust futexes: the kernel cleans up held futexes at * thread exit time. diff --git a/init/Kconfig b/init/Kconfig index a61c92066c2e..d87629ec7e48 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1555,6 +1555,13 @@ config FUTEX support for "fast userspace mutexes". The resulting kernel may not run glibc-based applications correctly. +config FUTEX2 + bool "Enable futex2 support" if EXPERT + depends on FUTEX + default y + help + Support for futex2 interface. + config FUTEX_PI bool depends on FUTEX && RT_MUTEXES diff --git a/kernel/Makefile b/kernel/Makefile index 4df609be42d0..1eaf2af50283 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -60,6 +60,7 @@ obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-y += time/ obj-$(CONFIG_FUTEX) += futex.o +obj-$(CONFIG_FUTEX2) += futex2.o obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o obj-$(CONFIG_SMP) += smp.o ifneq ($(CONFIG_SMP),y) diff --git a/kernel/futex.c b/kernel/futex.c index 2ecb07575055..ef7131bd8bc4 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -150,22 +150,6 @@ static int __read_mostly futex_cmpxchg_enabled; #endif -/* - * Futex flags used to encode options to functions and preserve them across - * restarts. - */ -#ifdef CONFIG_MMU -# define FLAGS_SHARED 0x01 -#else -/* - * NOMMU does not have per process address space. Let the compiler optimize - * code away. - */ -# define FLAGS_SHARED 0x00 -#endif -#define FLAGS_CLOCKRT 0x02 -#define FLAGS_HAS_TIMEOUT 0x04 - /* * Priority Inheritance state: */ @@ -1588,8 +1572,7 @@ double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) /* * Wake up waiters matching bitset queued on this futex (uaddr). */ -static int -futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) +int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) { struct futex_hash_bucket *hb; struct futex_q *this, *next; @@ -2676,8 +2659,8 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, return ret; } -static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, - ktime_t *abs_time, u32 bitset) +int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, + ktime_t *abs_time, u32 bitset) { struct hrtimer_sleeper timeout, *to; struct restart_block *restart; diff --git a/kernel/futex2.c b/kernel/futex2.c new file mode 100644 index 000000000000..990c665280fd --- /dev/null +++ b/kernel/futex2.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * futex2 system call interface by André Almeida + * + * Copyright 2021 Collabora Ltd. + */ + +#include + +#include + +/* + * Set of flags that futex2 accepts + */ +#define FUTEX2_MASK (FUTEX_SIZE_MASK | FUTEX_SHARED_FLAG | FUTEX_CLOCK_REALTIME) + +static long ksys_futex_wait(void __user *uaddr, u64 val, unsigned int flags, + struct __kernel_timespec __user *timo) +{ + unsigned int size = flags & FUTEX_SIZE_MASK, futex_flags = 0; + ktime_t *kt = NULL, time; + struct timespec64 ts; + + if (flags & ~FUTEX2_MASK) + return -EINVAL; + + if (flags & FUTEX_SHARED_FLAG) + futex_flags |= FLAGS_SHARED; + + if (flags & FUTEX_CLOCK_REALTIME) + futex_flags |= FLAGS_CLOCKRT; + + if (size != FUTEX_32) + return -EINVAL; + + if (timo) { + if (get_timespec64(&ts, timo)) + return -EFAULT; + + if (!timespec64_valid(&ts)) + return -EINVAL; + + time = timespec64_to_ktime(ts); + kt = &time; + } + + return futex_wait(uaddr, futex_flags, val, kt, FUTEX_BITSET_MATCH_ANY); +} + +/** + * sys_futex_wait - Wait on a futex address if (*uaddr) == val + * @uaddr: User address of futex + * @val: Expected value of futex + * @flags: Specify the size of futex and the clockid + * @timo: Optional absolute timeout. + * + * The user thread is put to sleep, waiting for a futex_wake() at uaddr, if the + * value at *uaddr is the same as val (otherwise, the syscall returns + * immediately with -EAGAIN). + * + * Returns 0 on success, error code otherwise. + */ +SYSCALL_DEFINE4(futex_wait, void __user *, uaddr, u64, val, unsigned int, flags, + struct __kernel_timespec __user *, timo) +{ + return ksys_futex_wait(uaddr, val, flags, timo); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(futex_wait, void __user *, uaddr, compat_u64, val, + unsigned int, flags, + struct __kernel_timespec __user *, timo) +{ + return ksys_futex_wait(uaddr, val, flags, timo); +} +#endif + +/** + * sys_futex_wake - Wake a number of futexes waiting on an address + * @uaddr: Address of futex to be woken up + * @nr_wake: Number of futexes waiting in uaddr to be woken up + * @flags: Flags for size and shared + * + * Wake `nr_wake` threads waiting at uaddr. + * + * Returns the number of woken threads on success, error code otherwise. + */ +SYSCALL_DEFINE3(futex_wake, void __user *, uaddr, unsigned int, nr_wake, + unsigned int, flags) +{ + unsigned int size = flags & FUTEX_SIZE_MASK, futex_flags = 0; + + if (flags & ~FUTEX2_MASK) + return -EINVAL; + + if (flags & FUTEX_SHARED_FLAG) + futex_flags |= FLAGS_SHARED; + + if (size != FUTEX_32) + return -EINVAL; + + return futex_wake(uaddr, futex_flags, nr_wake, FUTEX_BITSET_MATCH_ANY); +} diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 0ea8128468c3..dbe397eaea46 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -151,6 +151,11 @@ COND_SYSCALL_COMPAT(set_robust_list); COND_SYSCALL(get_robust_list); COND_SYSCALL_COMPAT(get_robust_list); +/* kernel/futex2.c */ +COND_SYSCALL(futex_wait); +COND_SYSCALL_COMPAT(futex_wait); +COND_SYSCALL(futex_wake); + /* kernel/hrtimer.c */ /* kernel/itimer.c */ From patchwork Fri Jul 9 00:13:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472528 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88ACDC07E96 for ; Fri, 9 Jul 2021 00:14:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C79561468 for ; Fri, 9 Jul 2021 00:14:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229956AbhGIAQw (ORCPT ); Thu, 8 Jul 2021 20:16:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhGIAQv (ORCPT ); Thu, 8 Jul 2021 20:16:51 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E8F8C061574; Thu, 8 Jul 2021 17:14:08 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 04F221F415F9 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 02/11] futex2: Implement vectorized wait Date: Thu, 8 Jul 2021 21:13:19 -0300 Message-Id: <20210709001328.329716-3-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add support to wait on multiple futexes. This is the interface implemented by this syscall: futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes, unsigned int flags, struct timespec *timo) struct futex_waitv { __u64 val; void *uaddr; unsigned int flags; }; Given an array of struct futex_waitv, wait on each uaddr. The thread wakes if a futex_wake() is performed at any uaddr. The syscall returns immediately if any waiter has *uaddr != val. *timo is an optional timeout value for the operation. The flags argument of the syscall should be used solely for specifying the timeout clock as realtime, if needed. Flags for shared futexes, sizes, etc. should be used on the individual flags of each waiter. Returns the array index of one of the awakened futexes. There’s no given information of how many were awakened, or any particular attribute of it (if it’s the first awakened, if it is of the smaller index...). Signed-off-by: André Almeida --- arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + include/linux/compat.h | 9 + include/linux/futex.h | 108 ++++++-- include/uapi/asm-generic/unistd.h | 4 +- include/uapi/linux/futex.h | 15 ++ kernel/futex.c | 72 +----- kernel/futex2.c | 345 +++++++++++++++++++++++++ kernel/sys_ni.c | 2 + 9 files changed, 477 insertions(+), 80 deletions(-) diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index e3b827a9c094..5573437c1914 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -453,3 +453,4 @@ 446 i386 landlock_restrict_self sys_landlock_restrict_self 447 i386 futex_wait sys_futex_wait compat_sys_futex_wait 448 i386 futex_wake sys_futex_wake +449 i386 futex_waitv sys_futex_waitv compat_sys_futex_waitv diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 63b447255df2..bad4aca3e9ba 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -370,6 +370,7 @@ 446 common landlock_restrict_self sys_landlock_restrict_self 447 common futex_wait sys_futex_wait 448 common futex_wake sys_futex_wake +449 common futex_waitv sys_futex_waitv # # Due to a historical design error, certain syscalls are numbered differently diff --git a/include/linux/compat.h b/include/linux/compat.h index 5a910e0c437a..75b90e41e05b 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -368,6 +368,12 @@ struct compat_robust_list_head { compat_uptr_t list_op_pending; }; +struct compat_futex_waitv { + compat_u64 val; + compat_uptr_t uaddr; + compat_uint_t flags; +}; + #ifdef CONFIG_COMPAT_OLD_SIGACTION struct compat_old_sigaction { compat_uptr_t sa_handler; @@ -696,6 +702,9 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, asmlinkage long compat_sys_futex_wait(void __user *uaddr, compat_u64 val, unsigned int flags, struct __kernel_timespec __user *timo); +asmlinkage long compat_sys_futex_waitv(struct compat_futex_waitv *waiters, + compat_uint_t nr_futexes, compat_uint_t flags, + struct __kernel_timespec __user *timo); /* kernel/itimer.c */ asmlinkage long compat_sys_getitimer(int which, struct old_itimerval32 __user *it); diff --git a/include/linux/futex.h b/include/linux/futex.h index f0eaa05ec8bc..7afef5bb3da2 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -29,6 +29,22 @@ struct task_struct; #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ +/* + * Futex flags used to encode options to functions and preserve them across + * restarts. + */ +#ifdef CONFIG_MMU +# define FLAGS_SHARED 0x01 +#else +/* + * NOMMU does not have per process address space. Let the compiler optimize + * code away. + */ +# define FLAGS_SHARED 0x00 +#endif +#define FLAGS_CLOCKRT 0x02 +#define FLAGS_HAS_TIMEOUT 0x04 + union futex_key { struct { u64 i_seq; @@ -50,6 +66,63 @@ union futex_key { } both; }; +/** + * struct futex_q - The hashed futex queue entry, one per waiting task + * @list: priority-sorted list of tasks waiting on this futex + * @task: the task waiting on the futex + * @lock_ptr: the hash bucket lock + * @key: the key the futex is hashed on + * @pi_state: optional priority inheritance state + * @rt_waiter: rt_waiter storage for use with requeue_pi + * @requeue_pi_key: the requeue_pi target futex key + * @bitset: bitset for the optional bitmasked wakeup + * + * We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so + * we can wake only the relevant ones (hashed queues may be shared). + * + * A futex_q has a woken state, just like tasks have TASK_RUNNING. + * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. + * The order of wakeup is always to make the first condition true, then + * the second. + * + * PI futexes are typically woken before they are removed from the hash list via + * the rt_mutex code. See unqueue_me_pi(). + */ +struct futex_q { + struct plist_node list; + + struct task_struct *task; + spinlock_t *lock_ptr; + union futex_key key; + struct futex_pi_state *pi_state; + struct rt_mutex_waiter *rt_waiter; + union futex_key *requeue_pi_key; + u32 bitset; +} __randomize_layout; + +/** + * struct futex_vector - Auxiliary struct for futex_waitv() + * @w: Userspace provided data + * @q: Kernel side data + * + * Struct used to build an array with all data need for futex_waitv() + */ +struct futex_vector { + struct futex_waitv w; + struct futex_q q; +}; + +/* + * Hash buckets are shared by all the futex_keys that hash to the same + * location. Each key may have multiple futex_q structures, one for each task + * waiting on a futex. + */ +struct futex_hash_bucket { + atomic_t waiters; + spinlock_t lock; + struct plist_head chain; +} ____cacheline_aligned_in_smp; + #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } } #ifdef CONFIG_FUTEX @@ -59,6 +132,11 @@ enum { FUTEX_STATE_DEAD, }; +enum futex_access { + FUTEX_READ, + FUTEX_WRITE +}; + static inline void futex_init_task(struct task_struct *tsk) { tsk->robust_list = NULL; @@ -81,22 +159,22 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset); int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset); +void queue_me(struct futex_q *q, struct futex_hash_bucket *hb); +int unqueue_me(struct futex_q *q); +void queue_unlock(struct futex_hash_bucket *hb); +int get_futex_value_locked(u32 *dest, u32 __user *from); +int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key, + enum futex_access rw); +struct futex_hash_bucket *queue_lock(struct futex_q *q); +struct hrtimer_sleeper *futex_setup_timer(ktime_t *time, + struct hrtimer_sleeper *timeout, + int flags, u64 range_ns); -/* - * Futex flags used to encode options to functions and preserve them across - * restarts. - */ -#ifdef CONFIG_MMU -# define FLAGS_SHARED 0x01 -#else -/* - * NOMMU does not have per process address space. Let the compiler optimize - * code away. - */ -# define FLAGS_SHARED 0x00 -#endif -#define FLAGS_CLOCKRT 0x02 -#define FLAGS_HAS_TIMEOUT 0x04 +static const struct futex_q futex_q_init = { + /* list gets initialized in queue_me()*/ + .key = FUTEX_KEY_INIT, + .bitset = FUTEX_BITSET_MATCH_ANY +}; #else static inline void futex_init_task(struct task_struct *tsk) { } diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index df9fe2e23ee0..57acb3a0f69f 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -876,9 +876,11 @@ __SYSCALL(__NR_landlock_restrict_self, sys_landlock_restrict_self) __SC_COMP(__NR_futex_wait, sys_futex_wait, compat_sys_futex_wait) #define __NR_futex_wake 448 __SYSCALL(__NR_futex_wake, sys_futex_wake) +#define __NR_futex_waitv 449 +__SC_COMP(__NR_futex_waitv, sys_futex_waitv, compat_sys_futex_waitv) #undef __NR_syscalls -#define __NR_syscalls 449 +#define __NR_syscalls 450 /* * 32 bit systems traditionally used different diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h index 44750caa261e..daa135bdedda 100644 --- a/include/uapi/linux/futex.h +++ b/include/uapi/linux/futex.h @@ -45,6 +45,21 @@ #define FUTEX_32 2 #define FUTEX_SHARED_FLAG 8 #define FUTEX_SIZE_MASK 0x3 + +#define FUTEX_WAITV_MAX 128 + +/** + * struct futex_waitv - A waiter for vectorized wait + * @val: Expected value at uaddr + * @uaddr: User address to wait on + * @flags: Flags for this waiter + */ +struct futex_waitv { + __u64 val; + void __user *uaddr; + unsigned int flags; +}; + /* * Support for robust futexes: the kernel cleans up held futexes at * thread exit time. diff --git a/kernel/futex.c b/kernel/futex.c index ef7131bd8bc4..135782fc3461 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -171,57 +171,6 @@ struct futex_pi_state { union futex_key key; } __randomize_layout; -/** - * struct futex_q - The hashed futex queue entry, one per waiting task - * @list: priority-sorted list of tasks waiting on this futex - * @task: the task waiting on the futex - * @lock_ptr: the hash bucket lock - * @key: the key the futex is hashed on - * @pi_state: optional priority inheritance state - * @rt_waiter: rt_waiter storage for use with requeue_pi - * @requeue_pi_key: the requeue_pi target futex key - * @bitset: bitset for the optional bitmasked wakeup - * - * We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so - * we can wake only the relevant ones (hashed queues may be shared). - * - * A futex_q has a woken state, just like tasks have TASK_RUNNING. - * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. - * The order of wakeup is always to make the first condition true, then - * the second. - * - * PI futexes are typically woken before they are removed from the hash list via - * the rt_mutex code. See unqueue_me_pi(). - */ -struct futex_q { - struct plist_node list; - - struct task_struct *task; - spinlock_t *lock_ptr; - union futex_key key; - struct futex_pi_state *pi_state; - struct rt_mutex_waiter *rt_waiter; - union futex_key *requeue_pi_key; - u32 bitset; -} __randomize_layout; - -static const struct futex_q futex_q_init = { - /* list gets initialized in queue_me()*/ - .key = FUTEX_KEY_INIT, - .bitset = FUTEX_BITSET_MATCH_ANY -}; - -/* - * Hash buckets are shared by all the futex_keys that hash to the same - * location. Each key may have multiple futex_q structures, one for each task - * waiting on a futex. - */ -struct futex_hash_bucket { - atomic_t waiters; - spinlock_t lock; - struct plist_head chain; -} ____cacheline_aligned_in_smp; - /* * The base of the bucket array and its size are always used together * (after initialization only in hash_futex()), so ensure that they @@ -364,11 +313,6 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2) && key1->both.offset == key2->both.offset); } -enum futex_access { - FUTEX_READ, - FUTEX_WRITE -}; - /** * futex_setup_timer - set up the sleeping hrtimer. * @time: ptr to the given timeout value @@ -379,7 +323,7 @@ enum futex_access { * Return: Initialized hrtimer_sleeper structure or NULL if no timeout * value given */ -static inline struct hrtimer_sleeper * +inline struct hrtimer_sleeper * futex_setup_timer(ktime_t *time, struct hrtimer_sleeper *timeout, int flags, u64 range_ns) { @@ -465,8 +409,8 @@ static u64 get_inode_sequence_number(struct inode *inode) * * lock_page() might sleep, the caller should not hold a spinlock. */ -static int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key, - enum futex_access rw) +int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key, + enum futex_access rw) { unsigned long address = (unsigned long)uaddr; struct mm_struct *mm = current->mm; @@ -698,7 +642,7 @@ static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr, return ret; } -static int get_futex_value_locked(u32 *dest, u32 __user *from) +inline int get_futex_value_locked(u32 *dest, u32 __user *from) { int ret; @@ -2173,7 +2117,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, } /* The key must be already stored in q->key. */ -static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) +inline struct futex_hash_bucket *queue_lock(struct futex_q *q) __acquires(&hb->lock) { struct futex_hash_bucket *hb; @@ -2196,7 +2140,7 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) return hb; } -static inline void +inline void queue_unlock(struct futex_hash_bucket *hb) __releases(&hb->lock) { @@ -2235,7 +2179,7 @@ static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb) * state is implicit in the state of woken task (see futex_wait_requeue_pi() for * an example). */ -static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) +inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) __releases(&hb->lock) { __queue_me(q, hb); @@ -2253,7 +2197,7 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) * - 1 - if the futex_q was still queued (and we removed unqueued it); * - 0 - if the futex_q was already removed by the waking thread */ -static int unqueue_me(struct futex_q *q) +int unqueue_me(struct futex_q *q) { spinlock_t *lock_ptr; int ret = 0; diff --git a/kernel/futex2.c b/kernel/futex2.c index 990c665280fd..cc1f31afb281 100644 --- a/kernel/futex2.c +++ b/kernel/futex2.c @@ -7,6 +7,7 @@ #include +#include #include /* @@ -14,6 +15,350 @@ */ #define FUTEX2_MASK (FUTEX_SIZE_MASK | FUTEX_SHARED_FLAG | FUTEX_CLOCK_REALTIME) +/* Mask for each futex in futex_waitv list */ +#define FUTEXV_WAITER_MASK (FUTEX_SIZE_MASK | FUTEX_SHARED_FLAG) + +/* Mask for sys_futex_waitv flag */ +#define FUTEXV_MASK (FUTEX_CLOCK_REALTIME) + +/** + * unqueue_multiple() - Remove various futexes from their futex_hash_bucket + * @v: The list of futexes to unqueue + * @count: Number of futexes in the list + * + * Helper to unqueue a list of futexes. This can't fail. + * + * Return: + * - >=0 - Index of the last futex that was awoken; + * - -1 - No futex was awoken + */ +static int unqueue_multiple(struct futex_vector *v, int count) +{ + int ret = -1, i; + + for (i = 0; i < count; i++) { + if (!unqueue_me(&v[i].q)) + ret = i; + } + + return ret; +} + +/** + * futex_wait_multiple_setup() - Prepare to wait and enqueue multiple futexes + * @vs: The corresponding futex list + * @count: The size of the list + * @awaken: Index of the last awoken futex (return parameter) + * + * Prepare multiple futexes in a single step and enqueue them. This may fail if + * the futex list is invalid or if any futex was already awoken. On success the + * task is ready to interruptible sleep. + * + * Return: + * - 1 - One of the futexes was awaken by another thread + * - 0 - Success + * - <0 - -EFAULT, -EWOULDBLOCK or -EINVAL + */ +static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *awaken) +{ + struct futex_hash_bucket *hb; + int ret, i; + u32 uval; + + /* + * Enqueuing multiple futexes is tricky, because we need to + * enqueue each futex in the list before dealing with the next + * one to avoid deadlocking on the hash bucket. But, before + * enqueuing, we need to make sure that current->state is + * TASK_INTERRUPTIBLE, so we don't absorb any awake events, which + * cannot be done before the get_futex_key of the next key, + * because it calls get_user_pages, which can sleep. Thus, we + * fetch the list of futexes keys in two steps, by first pinning + * all the memory keys in the futex key, and only then we read + * each key and queue the corresponding futex. + */ +retry: + for (i = 0; i < count; i++) { + ret = get_futex_key(vs[i].w.uaddr, + vs[i].w.flags & FUTEX_SHARED_FLAG, + &vs[i].q.key, FUTEX_READ); + if (unlikely(ret)) + return ret; + } + + set_current_state(TASK_INTERRUPTIBLE); + + for (i = 0; i < count; i++) { + struct futex_q *q = &vs[i].q; + struct futex_waitv *waitv = &vs[i].w; + + hb = queue_lock(q); + ret = get_futex_value_locked(&uval, waitv->uaddr); + if (ret) { + /* + * We need to try to handle the fault, which + * cannot be done without sleep, so we need to + * undo all the work already done, to make sure + * we don't miss any wake ups. Therefore, clean + * up, handle the fault and retry from the + * beginning. + */ + queue_unlock(hb); + __set_current_state(TASK_RUNNING); + + *awaken = unqueue_multiple(vs, i); + if (*awaken >= 0) + return 1; + + if (get_user(uval, (u32 __user *)waitv->uaddr)) + return -EINVAL; + + goto retry; + } + + if (uval != waitv->val) { + queue_unlock(hb); + __set_current_state(TASK_RUNNING); + + /* + * If something was already awaken, we can + * safely ignore the error and succeed. + */ + *awaken = unqueue_multiple(vs, i); + if (*awaken >= 0) + return 1; + + return -EWOULDBLOCK; + } + + /* + * The bucket lock can't be held while dealing with the + * next futex. Queue each futex at this moment so hb can + * be unlocked. + */ + queue_me(&vs[i].q, hb); + } + return 0; +} + +/** + * futex_wait_multiple() - Prepare to wait on and enqueue several futexes + * @vs: The list of futexes to wait on + * @count: The number of objects + * @to: Timeout before giving up and returning to userspace + * + * Entry point for the FUTEX_WAIT_MULTIPLE futex operation, this function + * sleeps on a group of futexes and returns on the first futex that + * triggered, or after the timeout has elapsed. + * + * Return: + * - >=0 - Hint to the futex that was awoken + * - <0 - On error + */ +static int futex_wait_multiple(struct futex_vector *vs, unsigned int count, + struct hrtimer_sleeper *to) +{ + int ret, hint = 0; + unsigned int i; + + while (1) { + ret = futex_wait_multiple_setup(vs, count, &hint); + if (ret) { + if (ret > 0) { + /* A futex was awaken during setup */ + ret = hint; + } + return ret; + } + + if (to) + hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS); + + /* + * Avoid sleeping if another thread already tried to + * wake us. + */ + for (i = 0; i < count; i++) { + if (plist_node_empty(&vs[i].q.list)) + break; + } + + if (i == count && (!to || to->task)) + freezable_schedule(); + + __set_current_state(TASK_RUNNING); + + ret = unqueue_multiple(vs, count); + if (ret >= 0) + return ret; + + if (to && !to->task) + return -ETIMEDOUT; + else if (signal_pending(current)) + return -ERESTARTSYS; + /* + * The final case is a spurious wakeup, for + * which just retry. + */ + } +} + +#ifdef CONFIG_COMPAT +/** + * compat_futex_parse_waitv - Parse a waitv array from userspace + * @futexv: Kernel side list of waiters to be filled + * @uwaitv: Userspace list to be parsed + * @nr_futexes: Length of futexv + * + * Return: Error code on failure, pointer to a prepared futexv otherwise + */ +static int compat_futex_parse_waitv(struct futex_vector *futexv, + struct compat_futex_waitv __user *uwaitv, + unsigned int nr_futexes) +{ + struct compat_futex_waitv aux; + unsigned int i; + + for (i = 0; i < nr_futexes; i++) { + if (copy_from_user(&aux, &uwaitv[i], sizeof(aux))) + return -EFAULT; + + if ((aux.flags & ~FUTEXV_WAITER_MASK) || + (aux.flags & FUTEX_SIZE_MASK) != FUTEX_32) + return -EINVAL; + + futexv[i].w.flags = aux.flags; + futexv[i].w.val = aux.val; + futexv[i].w.uaddr = compat_ptr(aux.uaddr); + futexv[i].q = futex_q_init; + } + + return 0; +} + +COMPAT_SYSCALL_DEFINE4(futex_waitv, struct compat_futex_waitv __user *, waiters, + unsigned int, nr_futexes, unsigned int, flags, + struct __kernel_timespec __user *, timo) +{ + struct hrtimer_sleeper to; + struct futex_vector *futexv; + struct timespec64 ts; + ktime_t time; + int ret; + + if (flags & ~FUTEXV_MASK) + return -EINVAL; + + if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters) + return -EINVAL; + + if (timo) { + int flag_clkid = 0; + + if (get_timespec64(&ts, timo)) + return -EFAULT; + + if (!timespec64_valid(&ts)) + return -EINVAL; + + if (flags & FUTEX_CLOCK_REALTIME) + flag_clkid = FLAGS_CLOCKRT; + + time = timespec64_to_ktime(ts); + futex_setup_timer(&time, &to, flag_clkid, 0); + } + + futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL); + if (!futexv) + return -ENOMEM; + + ret = compat_futex_parse_waitv(futexv, waiters, nr_futexes); + if (!ret) + ret = futex_wait_multiple(futexv, nr_futexes, timo ? &to : NULL); + + if (timo) { + hrtimer_cancel(&to.timer); + destroy_hrtimer_on_stack(&to.timer); + } + + kfree(futexv); + return ret; +} +#endif + +static int futex_parse_waitv(struct futex_vector *futexv, + struct futex_waitv __user *uwaitv, + unsigned int nr_futexes) +{ + struct futex_waitv aux; + unsigned int i; + + for (i = 0; i < nr_futexes; i++) { + if (copy_from_user(&aux, &uwaitv[i], sizeof(aux))) + return -EFAULT; + + if ((aux.flags & ~FUTEXV_WAITER_MASK) || + (aux.flags & FUTEX_SIZE_MASK) != FUTEX_32) + return -EINVAL; + + futexv[i].w.flags = aux.flags; + futexv[i].w.val = aux.val; + futexv[i].w.uaddr = aux.uaddr; + futexv[i].q = futex_q_init; + } + + return 0; +} + +SYSCALL_DEFINE4(futex_waitv, struct futex_waitv __user *, waiters, + unsigned int, nr_futexes, unsigned int, flags, + struct __kernel_timespec __user *, timo) +{ + struct hrtimer_sleeper to; + struct futex_vector *futexv; + struct timespec64 ts; + ktime_t time; + int ret; + + if (flags & ~FUTEXV_MASK) + return -EINVAL; + + if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters) + return -EINVAL; + + if (timo) { + int flag_clkid = 0; + + if (get_timespec64(&ts, timo)) + return -EFAULT; + + if (!timespec64_valid(&ts)) + return -EINVAL; + + if (flags & FUTEX_CLOCK_REALTIME) + flag_clkid = FLAGS_CLOCKRT; + + time = timespec64_to_ktime(ts); + futex_setup_timer(&time, &to, flag_clkid, 0); + } + + futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL); + if (!futexv) + return -ENOMEM; + + ret = futex_parse_waitv(futexv, waiters, nr_futexes); + if (!ret) + ret = futex_wait_multiple(futexv, nr_futexes, timo ? &to : NULL); + + if (timo) { + hrtimer_cancel(&to.timer); + destroy_hrtimer_on_stack(&to.timer); + } + + kfree(futexv); + return ret; +} + static long ksys_futex_wait(void __user *uaddr, u64 val, unsigned int flags, struct __kernel_timespec __user *timo) { diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index dbe397eaea46..93807bb7be51 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -155,6 +155,8 @@ COND_SYSCALL_COMPAT(get_robust_list); COND_SYSCALL(futex_wait); COND_SYSCALL_COMPAT(futex_wait); COND_SYSCALL(futex_wake); +COND_SYSCALL(futex_waitv); +COND_SYSCALL_COMPAT(futex_waitv); /* kernel/hrtimer.c */ From patchwork Fri Jul 9 00:13:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472107 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70FECC07E9C for ; Fri, 9 Jul 2021 00:14:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 527F26146B for ; Fri, 9 Jul 2021 00:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229637AbhGIAQ6 (ORCPT ); Thu, 8 Jul 2021 20:16:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhGIAQ5 (ORCPT ); Thu, 8 Jul 2021 20:16:57 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 220D4C061574; Thu, 8 Jul 2021 17:14:15 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id C3F5E1F421A2 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 03/11] futex2: Implement requeue operation Date: Thu, 8 Jul 2021 21:13:20 -0300 Message-Id: <20210709001328.329716-4-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Implement requeue interface similarly to FUTEX_CMP_REQUEUE operation. This is the syscall implemented by this patch: futex_requeue(struct futex_requeue *rq1, struct futex_requeue *rq2, unsigned int nr_wake, unsigned int nr_requeue, u64 cmpval, unsigned int flags) struct futex_requeue { void *uaddr; unsigned int flags; }; If (rq1->uaddr == cmpval), wake at rq1->uaddr a nr_wake number of waiters and then, remove a number of nr_requeue waiters at rq1->uaddr and add them to rq2->uaddr list. Each uaddr has its own set of flags, that must be defined at struct futex_requeue (such as size, shared, NUMA). The flags argument of the syscall is there just for the sake of extensibility, and right now it needs to be zero. Return the number of the woken futexes + the number of requeued ones on success, error code otherwise. Signed-off-by: André Almeida --- The original FUTEX_CMP_REQUEUE interfaces is such as follows: futex(*uaddr1, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, *uaddr2, cmpval); Given that when this interface was created they was only one type of futex (as opposed to futex2, where there is shared, sizes, and NUMA), there was no way to specify individual flags for uaddr1 and 2. When FUTEX_PRIVATE was implemented, a new opcode was created as well (FUTEX_CMP_REQUEUE_PRIVATE), but they apply both futexes, so they should be of the same type regarding private/shared. This imposes a limitation on the use cases of the operation, and to overcome that at futex2, `struct futex_requeue` was created, so one can set individual flags for each futex. This flexibility is a trade-off with performance, given that now we need to perform two extra copy_from_user(). One alternative would be to use the upper half of flags bits to the first one, and the bottom half for the second futex, but this would also impose limitations, given that we would limit by half the flags possibilities. If equal futexes are common enough, the following extension could be added to overcome the current performance: - A flag FUTEX_REQUEUE_EQUAL is added to futex2() flags; - If futex_requeue() see this flag, that means that both futexes uses the same set of attributes. - Then, the function parses the flags as of futex_wait/wake(). - *rq1 and *rq2 are used as void* (instead of struct futex_requeue) just like wait/wake(). In that way, we could avoid the copy_from_user(). --- arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + include/linux/compat.h | 10 +++ include/linux/futex.h | 3 + include/uapi/asm-generic/unistd.h | 4 +- include/uapi/linux/futex.h | 10 +++ kernel/futex.c | 18 ++-- kernel/futex2.c | 111 +++++++++++++++++++++++++ kernel/sys_ni.c | 2 + 9 files changed, 150 insertions(+), 10 deletions(-) diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 5573437c1914..f02c3da76945 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -454,3 +454,4 @@ 447 i386 futex_wait sys_futex_wait compat_sys_futex_wait 448 i386 futex_wake sys_futex_wake 449 i386 futex_waitv sys_futex_waitv compat_sys_futex_waitv +450 i386 futex_requeue sys_futex_requeue compat_sys_futex_requeue diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index bad4aca3e9ba..8815c0de5d05 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -371,6 +371,7 @@ 447 common futex_wait sys_futex_wait 448 common futex_wake sys_futex_wake 449 common futex_waitv sys_futex_waitv +450 common futex_requeue sys_futex_requeue # # Due to a historical design error, certain syscalls are numbered differently diff --git a/include/linux/compat.h b/include/linux/compat.h index 75b90e41e05b..861616de6d75 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -374,6 +374,11 @@ struct compat_futex_waitv { compat_uint_t flags; }; +struct compat_futex_requeue { + compat_uptr_t uaddr; + compat_uint_t flags; +}; + #ifdef CONFIG_COMPAT_OLD_SIGACTION struct compat_old_sigaction { compat_uptr_t sa_handler; @@ -705,6 +710,11 @@ asmlinkage long compat_sys_futex_wait(void __user *uaddr, compat_u64 val, asmlinkage long compat_sys_futex_waitv(struct compat_futex_waitv *waiters, compat_uint_t nr_futexes, compat_uint_t flags, struct __kernel_timespec __user *timo); +asmlinkage long compat_sys_futex_requeue(struct futex_requeue __user *rq1, + struct futex_requeue __user *rq2, + unsigned int nr_wake, + unsigned int nr_requeue, + u64 cmpval, unsigned int flags); /* kernel/itimer.c */ asmlinkage long compat_sys_getitimer(int which, struct old_itimerval32 __user *it); diff --git a/include/linux/futex.h b/include/linux/futex.h index 7afef5bb3da2..95afac7b2f76 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -159,6 +159,9 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset); int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset); +int futex_requeue(u32 __user *uaddr1, unsigned int flags1, u32 __user *uaddr2, + unsigned int flags2, int nr_wake, int nr_requeue, u32 *cmpval, + int requeue_pi); void queue_me(struct futex_q *q, struct futex_hash_bucket *hb); int unqueue_me(struct futex_q *q); void queue_unlock(struct futex_hash_bucket *hb); diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 57acb3a0f69f..89a480490dca 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -878,9 +878,11 @@ __SC_COMP(__NR_futex_wait, sys_futex_wait, compat_sys_futex_wait) __SYSCALL(__NR_futex_wake, sys_futex_wake) #define __NR_futex_waitv 449 __SC_COMP(__NR_futex_waitv, sys_futex_waitv, compat_sys_futex_waitv) +#define __NR_futex_requeue 450 +__SC_COMP(__NR_futex_requeue, sys_futex_requeue, compat_sys_futex_requeue) #undef __NR_syscalls -#define __NR_syscalls 450 +#define __NR_syscalls 451 /* * 32 bit systems traditionally used different diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h index daa135bdedda..7effdd568699 100644 --- a/include/uapi/linux/futex.h +++ b/include/uapi/linux/futex.h @@ -60,6 +60,16 @@ struct futex_waitv { unsigned int flags; }; +/** + * struct futex_requeue - Define an address and its flags for requeue operation + * @uaddr: User address of one of the requeue arguments + * @flags: Flags for this address + */ +struct futex_requeue { + void __user *uaddr; + unsigned int flags; +}; + /* * Support for robust futexes: the kernel cleans up held futexes at * thread exit time. diff --git a/kernel/futex.c b/kernel/futex.c index 135782fc3461..7e6d70195d8a 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1843,9 +1843,9 @@ futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1, * - >=0 - on success, the number of tasks requeued or woken; * - <0 - on error */ -static int futex_requeue(u32 __user *uaddr1, unsigned int flags, - u32 __user *uaddr2, int nr_wake, int nr_requeue, - u32 *cmpval, int requeue_pi) +int futex_requeue(u32 __user *uaddr1, unsigned int flags1, u32 __user *uaddr2, + unsigned int flags2, int nr_wake, int nr_requeue, + u32 *cmpval, int requeue_pi) { union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; int task_count = 0, ret; @@ -1895,10 +1895,10 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, } retry: - ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, FUTEX_READ); + ret = get_futex_key(uaddr1, flags1 & FLAGS_SHARED, &key1, FUTEX_READ); if (unlikely(ret != 0)) return ret; - ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, + ret = get_futex_key(uaddr2, flags2 & FLAGS_SHARED, &key2, requeue_pi ? FUTEX_WRITE : FUTEX_READ); if (unlikely(ret != 0)) return ret; @@ -1930,7 +1930,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, if (ret) return ret; - if (!(flags & FLAGS_SHARED)) + if (!(flags1 & FLAGS_SHARED)) goto retry_private; goto retry; @@ -3661,9 +3661,9 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, case FUTEX_WAKE_BITSET: return futex_wake(uaddr, flags, val, val3); case FUTEX_REQUEUE: - return futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0); + return futex_requeue(uaddr, flags, uaddr2, flags, val, val2, NULL, 0); case FUTEX_CMP_REQUEUE: - return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0); + return futex_requeue(uaddr, flags, uaddr2, flags, val, val2, &val3, 0); case FUTEX_WAKE_OP: return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3); case FUTEX_LOCK_PI: @@ -3680,7 +3680,7 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, return futex_wait_requeue_pi(uaddr, flags, val, timeout, val3, uaddr2); case FUTEX_CMP_REQUEUE_PI: - return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1); + return futex_requeue(uaddr, flags, uaddr2, flags, val, val2, &val3, 1); } return -ENOSYS; } diff --git a/kernel/futex2.c b/kernel/futex2.c index cc1f31afb281..4f6d099badec 100644 --- a/kernel/futex2.c +++ b/kernel/futex2.c @@ -446,3 +446,114 @@ SYSCALL_DEFINE3(futex_wake, void __user *, uaddr, unsigned int, nr_wake, return futex_wake(uaddr, futex_flags, nr_wake, FUTEX_BITSET_MATCH_ANY); } + +#ifdef CONFIG_COMPAT +static int compat_futex_parse_requeue(struct compat_futex_requeue __user *rq, + void __user **uaddr, unsigned int *flags) +{ + struct compat_futex_requeue aux; + unsigned int futex_flags = 0; + + if (copy_from_user(&aux, rq, sizeof(*rq))) + return -EFAULT; + + if (aux.flags & ~FUTEXV_WAITER_MASK || + (aux.flags & FUTEX_SIZE_MASK) != FUTEX_32) + return -EINVAL; + + if (aux.flags & FUTEX_SHARED_FLAG) + futex_flags |= FLAGS_SHARED; + + *uaddr = compat_ptr(aux.uaddr); + *flags = futex_flags; + + return 0; +} + +COMPAT_SYSCALL_DEFINE6(futex_requeue, struct compat_futex_requeue __user *, rq1, + struct compat_futex_requeue __user *, rq2, + unsigned int, nr_wake, unsigned int, nr_requeue, + compat_u64, cmpval, unsigned int, flags) +{ + void __user *uaddr1, *uaddr2; + unsigned int flags1, flags2; + u32 val = cmpval; + int ret; + + if (flags) + return -EINVAL; + + ret = compat_futex_parse_requeue(rq1, &uaddr1, &flags1); + if (ret) + return ret; + + ret = compat_futex_parse_requeue(rq2, &uaddr2, &flags2); + if (ret) + return ret; + + return futex_requeue(uaddr1, flags1, uaddr2, flags2, nr_wake, nr_requeue, &val, 0); +} +#endif + +static int futex_parse_requeue(struct futex_requeue __user *rq, + void __user **uaddr, unsigned int *flags) +{ + struct futex_requeue aux; + unsigned int futex_flags = 0; + + if (copy_from_user(&aux, rq, sizeof(*rq))) + return -EFAULT; + + if (aux.flags & ~FUTEXV_WAITER_MASK || + (aux.flags & FUTEX_SIZE_MASK) != FUTEX_32) + return -EINVAL; + + if (aux.flags & FUTEX_SHARED_FLAG) + futex_flags |= FLAGS_SHARED; + + *uaddr = aux.uaddr; + *flags = futex_flags; + + return 0; +} + +/** + * sys_futex_requeue - Wake futexes at rq1 and requeue from rq1 to rq2 + * @rq1: Address of futexes to be waken/dequeued + * @rq2: Address for the futexes to be enqueued + * @nr_wake: Number of futexes waiting in uaddr1 to be woken up + * @nr_requeue: Number of futexes to be requeued from uaddr1 to uaddr2 + * @cmpval: Expected value at uaddr1 + * @flags: Reserved flags arg for requeue operation expansion. Must be 0. + * + * If (rq1->uaddr == cmpval), wake at uaddr1->uaddr a nr_wake number of + * waiters and then, remove a number of nr_requeue waiters at rq1->uaddr + * and add then to rq2->uaddr list. Each uaddr has its own set of flags, + * that must be defined at struct futex_requeue (such as size, shared, NUMA). + * + * Return the number of the woken futexes + the number of requeued ones on + * success, error code otherwise. + */ +SYSCALL_DEFINE6(futex_requeue, struct futex_requeue __user *, rq1, + struct futex_requeue __user *, rq2, + unsigned int, nr_wake, unsigned int, nr_requeue, + u64, cmpval, unsigned int, flags) +{ + void __user *uaddr1, *uaddr2; + unsigned int flags1, flags2; + u32 val = cmpval; + int ret; + + if (flags) + return -EINVAL; + + ret = futex_parse_requeue(rq1, &uaddr1, &flags1); + if (ret) + return ret; + + ret = futex_parse_requeue(rq2, &uaddr2, &flags2); + if (ret) + return ret; + + return futex_requeue(uaddr1, flags1, uaddr2, flags2, nr_wake, nr_requeue, &val, 0); +} diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 93807bb7be51..20a425b79fca 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -157,6 +157,8 @@ COND_SYSCALL_COMPAT(futex_wait); COND_SYSCALL(futex_wake); COND_SYSCALL(futex_waitv); COND_SYSCALL_COMPAT(futex_waitv); +COND_SYSCALL(futex_requeue); +COND_SYSCALL_COMPAT(futex_requeue); /* kernel/hrtimer.c */ From patchwork Fri Jul 9 00:13:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472527 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90402C07E99 for ; Fri, 9 Jul 2021 00:14:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76C1561477 for ; Fri, 9 Jul 2021 00:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229497AbhGIARE (ORCPT ); Thu, 8 Jul 2021 20:17:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230103AbhGIARE (ORCPT ); Thu, 8 Jul 2021 20:17:04 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9139BC061574; Thu, 8 Jul 2021 17:14:21 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 4E9701F41790 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 04/11] docs: locking: futex2: Add documentation Date: Thu, 8 Jul 2021 21:13:21 -0300 Message-Id: <20210709001328.329716-5-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add a new documentation file specifying both userspace API and internal implementation details of futex2 syscalls. Signed-off-by: André Almeida --- Documentation/locking/futex2.rst | 185 +++++++++++++++++++++++++++++++ Documentation/locking/index.rst | 1 + 2 files changed, 186 insertions(+) create mode 100644 Documentation/locking/futex2.rst diff --git a/Documentation/locking/futex2.rst b/Documentation/locking/futex2.rst new file mode 100644 index 000000000000..2bf40f2abd00 --- /dev/null +++ b/Documentation/locking/futex2.rst @@ -0,0 +1,185 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====== +futex2 +====== + +:Author: André Almeida + +futex, or fast user mutex, is a set of syscalls to allow userspace to create +performant synchronization mechanisms, such as mutexes, semaphores and +conditional variables in userspace. C standard libraries, like glibc, uses it +as a means to implement more high level interfaces like pthreads. + +The interface +============= + +uAPI functions +-------------- + +.. kernel-doc:: kernel/futex2.c + :identifiers: sys_futex_wait sys_futex_wake sys_futex_waitv sys_futex_requeue + +uAPI structures +--------------- + +.. kernel-doc:: include/uapi/linux/futex.h + +The ``flag`` argument +--------------------- + +The flag is used to specify the size of the futex word +(FUTEX_[8, 16, 32, 64]). It's mandatory to define one, since there's no +default size. + +By default, the timeout uses a monotonic clock, but can be used as a realtime +one by using the FUTEX_REALTIME_CLOCK flag. + +By default, futexes are of the private type, that means that this user address +will be accessed by threads that share the same memory region. This allows for +some internal optimizations, so they are faster. However, if the address needs +to be shared with different processes (like using ``mmap()`` or ``shm()``), they +need to be defined as shared and the flag FUTEX_SHARED_FLAG is used to set that. + +By default, the operation has no NUMA-awareness, meaning that the user can't +choose the memory node where the kernel side futex data will be stored. The +user can choose the node where it wants to operate by setting the +FUTEX_NUMA_FLAG and using the following structure (where X can be 8, 16, 32 or +64):: + + struct futexX_numa { + __uX value; + __sX hint; + }; + +This structure should be passed at the ``void *uaddr`` of futex functions. The +address of the structure will be used to be waited on/waken on, and the +``value`` will be compared to ``val`` as usual. The ``hint`` member is used to +define which node the futex will use. When waiting, the futex will be +registered on a kernel-side table stored on that node; when waking, the futex +will be searched for on that given table. That means that there's no redundancy +between tables, and the wrong ``hint`` value will lead to undesired behavior. +Userspace is responsible for dealing with node migrations issues that may +occur. ``hint`` can range from [0, MAX_NUMA_NODES), for specifying a node, or +-1, to use the same node the current process is using. + +When not using FUTEX_NUMA_FLAG on a NUMA system, the futex will be stored on a +global table on allocated on the first node. + +The ``timo`` argument +--------------------- + +As per the Y2038 work done in the kernel, new interfaces shouldn't add timeout +options known to be buggy. Given that, ``timo`` should be a 64-bit timeout at +all platforms, using an absolute timeout value. + +Implementation +============== + +Kernel side implementation is made on top of current futex codebase. + +Waiting +------- + +We have a hash table, where waiters register themselves before sleeping. Then +the wake function checks this table looking for waiters at uaddr. The hash +bucket to be used is determined by a struct futex_key, that stores information +to uniquely identify an address from a given process. Given the huge address +space, there'll be hash collisions, so we store information to be later used on +collision treatment. + +First, for every futex we want to wait on, we check if (``*uaddr == val``). +This check is done holding the bucket lock, so we are correctly serialized with +any futex_wake() calls. If any waiter fails the check above we return. For +futex_waitv() calls, we dequeue all futexes queue until this point. The check +(``*uaddr == val``) can fail for two reasons: + +- The values are different, and we return -EAGAIN. However, if while + dequeueing we found that some futexes were awakened, we prioritize this + and return success. + +- When trying to access the user address, we do so with page faults + disabled because we are holding a bucket's spin lock (and can't sleep + while holding a spin lock). If there's an error, it might be a page + fault, or an invalid address. We release the lock, dequeue everyone if it's a + futex_waitv() call (because it's illegal to sleep while there are futexes + enqueued, we could lose wakeups) and try again with page fault enabled. If we + succeed, this means that the address is valid, but we need to do all the work + again. For serialization reasons, we need to have the spin lock when getting + the user value. Additionally, for shared futexes, we also need to recalculate + the hash, since the underlying mapping mechanisms could have changed when + dealing with page fault. If, even with page fault enabled, we can't access + the address, it means it's an invalid user address, and we return -EFAULT. + +If the check is OK, they are enqueued on a linked list in our bucket, and +proceed to the next one. If all waiters succeed, we put the thread to sleep +until a futex_wake() call, timeout expires or we get a signal. After waking up, +we dequeue everyone, and check if some futex was awakened. + +All enqueuing/dequeuing operations requires to hold the bucket lock, to avoid +racing while modifying the list. + +Waking +------ + +We get the bucket that's storing the waiters at uaddr, and wake the required +number of waiters, checking for hash collision. + +There's an optimization that makes futex_wake() not take the bucket lock if +there's no one to be woken on that bucket. It checks an atomic counter that each +bucket has, if it says 0, then the syscall exits. In order for this to work, the +waiter thread increases it before taking the lock, so the wake thread will +correctly see that there's someone waiting and will continue the path to take +the bucket lock. To get the correct serialization, the waiter issues a memory +barrier after increasing the bucket counter and the waker issues a memory +barrier before checking it. + +Requeuing +--------- + +The requeue path first checks for each struct futex_requeue and their flags. +Then, it will compare the expected value with the one at rq1::uaddr. +Following the same serialization explained at Waking_, we increase the atomic +counter for the bucket of rq2::uaddr before taking the lock. We need to have +both buckets locks at same time so we don't race with other futex operation. To +ensure the locks are taken in the same order for all threads (and thus avoiding +deadlocks), every requeue operation takes the "smaller" bucket first, when +comparing both addresses. + +If the compare with user value succeeds, we proceed by waking ``nr_wake`` +futexes, and then requeuing ``nr_requeue`` from bucket of uaddr1 to the uaddr2. +This consists in a simple list deletion/addition and replacing the old futex key +with the new one. + +Futex keys +---------- + +There are two types of futexes: private and shared ones. The private are futexes +meant to be used by threads that share the same memory space, are easier to be +uniquely identified and thus can have some performance optimization. The +elements for identifying one are: the start address of the page where the +address is, the address offset within the page and the current->mm pointer. + +Now, for uniquely identifying a shared futex: + +- If the page containing the user address is an anonymous page, we can + just use the same data used for private futexes (the start address of + the page, the address offset within the page and the current->mm + pointer); that will be enough for uniquely identifying such futex. We + also set one bit at the key to differentiate if a private futex is + used on the same address (mixing shared and private calls does not + work). + +- If the page is file-backed, current->mm maybe isn't the same one for + every user of this futex, so we need to use other data: the + page->index, a UUID for the struct inode and the offset within the + page. + +Note that members of futex_key don't have any particular meaning after they +are part of the struct - they are just bytes to identify a futex. + +Source code documentation +========================= + +.. kernel-doc:: kernel/futex2.c + :no-identifiers: sys_futex_wait sys_futex_wake sys_futex_waitv sys_futex_requeue diff --git a/Documentation/locking/index.rst b/Documentation/locking/index.rst index 7003bd5aeff4..9bf03c7fa1ec 100644 --- a/Documentation/locking/index.rst +++ b/Documentation/locking/index.rst @@ -24,6 +24,7 @@ locking percpu-rw-semaphore robust-futexes robust-futex-ABI + futex2 .. only:: subproject and html From patchwork Fri Jul 9 00:13:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472106 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69210C07E96 for ; Fri, 9 Jul 2021 00:14:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 475BA61404 for ; Fri, 9 Jul 2021 00:14:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229843AbhGIARM (ORCPT ); Thu, 8 Jul 2021 20:17:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230135AbhGIARK (ORCPT ); Thu, 8 Jul 2021 20:17:10 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1EC2AC061760; Thu, 8 Jul 2021 17:14:28 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id BBDC01F4186C From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 05/11] selftests: futex2: Add wake/wait test Date: Thu, 8 Jul 2021 21:13:22 -0300 Message-Id: <20210709001328.329716-6-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add a simple file to test wake/wait mechanism using futex2 interface. Test three scenarios: using a common local int variable as private futex, a shm futex as shared futex and a file-backed shared memory as a shared futex. This should test all branches of futex_get_key(). Create helper files so more tests can evaluate futex2. While 32bit ABIs from glibc aren't yet able to use 64 bit sized time variables, add a temporary workaround that implements the required types and calls the appropriated syscalls, since futex2 doesn't supports 32 bit sized time. Signed-off-by: André Almeida --- .../selftests/futex/functional/.gitignore | 1 + .../selftests/futex/functional/Makefile | 4 +- .../selftests/futex/functional/futex2_wait.c | 195 ++++++++++++++++++ .../testing/selftests/futex/functional/run.sh | 3 + .../selftests/futex/include/futex2test.h | 79 +++++++ 5 files changed, 281 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/futex/functional/futex2_wait.c create mode 100644 tools/testing/selftests/futex/include/futex2test.h diff --git a/tools/testing/selftests/futex/functional/.gitignore b/tools/testing/selftests/futex/functional/.gitignore index 0e78b49d0f2f..3e2d577c0595 100644 --- a/tools/testing/selftests/futex/functional/.gitignore +++ b/tools/testing/selftests/futex/functional/.gitignore @@ -8,3 +8,4 @@ futex_wait_uninitialized_heap futex_wait_wouldblock futex_wait futex_requeue +futex2_wait diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile index bd1fec59e010..e4e4aa2e0368 100644 --- a/tools/testing/selftests/futex/functional/Makefile +++ b/tools/testing/selftests/futex/functional/Makefile @@ -6,6 +6,7 @@ LDLIBS := -lpthread -lrt HEADERS := \ ../include/futextest.h \ + ../include/futex2test.h \ ../include/atomic.h \ ../include/logging.h TEST_GEN_FILES := \ @@ -17,7 +18,8 @@ TEST_GEN_FILES := \ futex_wait_uninitialized_heap \ futex_wait_private_mapped_file \ futex_wait \ - futex_requeue + futex_requeue \ + futex2_wait TEST_PROGS := run.sh diff --git a/tools/testing/selftests/futex/functional/futex2_wait.c b/tools/testing/selftests/futex/functional/futex2_wait.c new file mode 100644 index 000000000000..25ac6d0898f5 --- /dev/null +++ b/tools/testing/selftests/futex/functional/futex2_wait.c @@ -0,0 +1,195 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/****************************************************************************** + * + * Copyright Collabora Ltd., 2021 + * + * DESCRIPTION + * Test wait/wake mechanism of futex2, using 32bit sized futexes. + * + * AUTHOR + * André Almeida + * + * HISTORY + * 2021-Feb-5: Initial version by André + * + *****************************************************************************/ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "futex2test.h" +#include "logging.h" + +#define TEST_NAME "futex2-wait" +#define timeout_ns 30000000 +#define WAKE_WAIT_US 10000 +#define SHM_PATH "futex2_shm_file" + +void *futex; + +void usage(char *prog) +{ + printf("Usage: %s\n", prog); + printf(" -c Use color\n"); + printf(" -h Display this help message\n"); + printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n", + VQUIET, VCRITICAL, VINFO); +} + +static void *waiterfn(void *arg) +{ + struct timespec64 to64; + unsigned int flags = 0; + + if (arg) + flags = *((unsigned int *) arg); + + /* setting absolute timeout for futex2 */ + if (gettime64(CLOCK_MONOTONIC, &to64)) + error("gettime64 failed\n", errno); + + to64.tv_nsec += timeout_ns; + + if (to64.tv_nsec >= 1000000000) { + to64.tv_sec++; + to64.tv_nsec -= 1000000000; + } + + if (futex2_wait(futex, 0, FUTEX_32 | flags, &to64)) + printf("waiter failed errno %d\n", errno); + + return NULL; +} + +int main(int argc, char *argv[]) +{ + unsigned int flags = FUTEX_SHARED_FLAG; + int res, ret = RET_PASS, fd, c, shm_id; + u_int32_t f_private = 0, *shared_data; + pthread_t waiter; + void *shm; + + futex = &f_private; + + while ((c = getopt(argc, argv, "cht:v:")) != -1) { + switch (c) { + case 'c': + log_color(1); + break; + case 'h': + usage(basename(argv[0])); + exit(0); + case 'v': + log_verbosity(atoi(optarg)); + break; + default: + usage(basename(argv[0])); + exit(1); + } + } + + ksft_print_header(); + ksft_set_plan(3); + ksft_print_msg("%s: Test FUTEX2_WAIT\n", basename(argv[0])); + + /* Testing a private futex */ + info("Calling private futex2_wait on futex: %p\n", futex); + if (pthread_create(&waiter, NULL, waiterfn, NULL)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + info("Calling private futex2_wake on futex: %p\n", futex); + res = futex2_wake(futex, 1, FUTEX_32); + if (res != 1) { + ksft_test_result_fail("futex2_wake private returned: %d %s\n", + errno, strerror(errno)); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_wake private\n"); + } + + /* Testing an anon page shared memory */ + shm_id = shmget(IPC_PRIVATE, 4096, IPC_CREAT | 0666); + if (shm_id < 0) { + perror("shmget"); + exit(1); + } + + shared_data = shmat(shm_id, NULL, 0); + + *shared_data = 0; + futex = shared_data; + + info("Calling (page anon) shared futex2_wait on futex: %p\n", futex); + if (pthread_create(&waiter, NULL, waiterfn, &flags)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + info("Calling (page anon) shared futex2_wake on futex: %p\n", futex); + res = futex2_wake(futex, 1, FUTEX_32 | FUTEX_SHARED_FLAG); + if (res != 1) { + ksft_test_result_fail("futex2_wake shared (page anon) returned: %d %s\n", + errno, strerror(errno)); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_wake shared (page anon)\n"); + } + + + /* Testing a file backed shared memory */ + fd = open(SHM_PATH, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR); + if (fd < 0) { + perror("open"); + exit(1); + } + + if (ftruncate(fd, sizeof(f_private))) { + perror("ftruncate"); + exit(1); + } + + shm = mmap(NULL, sizeof(f_private), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (shm == MAP_FAILED) { + perror("mmap"); + exit(1); + } + + memcpy(shm, &f_private, sizeof(f_private)); + + futex = shm; + + info("Calling shared (file backed) futex2_wait on futex: %p\n", futex); + if (pthread_create(&waiter, NULL, waiterfn, &flags)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + info("Calling shared (file backed) futex2_wake on futex: %p\n", futex); + res = futex2_wake(shm, 1, FUTEX_32 | FUTEX_SHARED_FLAG); + if (res != 1) { + ksft_test_result_fail("futex2_wake shared (file backed) returned: %d %s\n", + errno, strerror(errno)); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_wake shared (file backed)\n"); + } + + /* Freeing resources */ + shmdt(shared_data); + munmap(shm, sizeof(f_private)); + remove(SHM_PATH); + + ksft_print_cnts(); + return ret; +} diff --git a/tools/testing/selftests/futex/functional/run.sh b/tools/testing/selftests/futex/functional/run.sh index 11a9d62290f5..dbe82275617c 100755 --- a/tools/testing/selftests/futex/functional/run.sh +++ b/tools/testing/selftests/futex/functional/run.sh @@ -79,3 +79,6 @@ echo echo ./futex_requeue $COLOR + +echo +./futex2_wait $COLOR diff --git a/tools/testing/selftests/futex/include/futex2test.h b/tools/testing/selftests/futex/include/futex2test.h new file mode 100644 index 000000000000..e724d56b917e --- /dev/null +++ b/tools/testing/selftests/futex/include/futex2test.h @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/****************************************************************************** + * + * Copyright Collabora Ltd., 2021 + * + * DESCRIPTION + * Futex2 library addons for old futex library + * + * AUTHOR + * André Almeida + * + * HISTORY + * 2021-Feb-5: Initial version by André + * + *****************************************************************************/ +#include "futextest.h" +#include + +#define NSEC_PER_SEC 1000000000L + +#ifndef FUTEX_8 +# define FUTEX_8 0 +#endif +#ifndef FUTEX_16 +# define FUTEX_16 1 +#endif +#ifndef FUTEX_32 +# define FUTEX_32 2 +#endif + +/* + * - Y2038 section for 32-bit applications - + * + * Remove this when glibc is ready for y2038. Then, always compile with + * `-DTIME_BITS=64` or `-D__USE_TIME_BITS64`. glibc will provide both + * timespec64 and clock_gettime64 so we won't need to define here. + */ +#if defined(__i386__) || __TIMESIZE == 32 +# define NR_gettime __NR_clock_gettime64 +#else +# define NR_gettime __NR_clock_gettime +#endif + +struct timespec64 { + long long tv_sec; /* seconds */ + long long tv_nsec; /* nanoseconds */ +}; + +int gettime64(clock_t clockid, struct timespec64 *tv) +{ + return syscall(NR_gettime, clockid, tv); +} +/* + * - End of Y2038 section - + */ + +/** + * futex2_wait - If (*uaddr == val), wait at uaddr until timo + * @uaddr: User address to wait on + * @val: Expected value at uaddr, return if is not equal + * @flags: Operation flags + * @timo: Optional timeout for operation + */ +static inline int futex2_wait(volatile void *uaddr, unsigned long val, + unsigned long flags, struct timespec64 *timo) +{ + return syscall(__NR_futex_wait, uaddr, val, flags, timo); +} + +/** + * futex2_wake - Wake a number of waiters at uaddr + * @uaddr: Address to wake + * @nr: Number of waiters to wake + * @flags: Operation flags + */ +static inline int futex2_wake(volatile void *uaddr, unsigned int nr, unsigned long flags) +{ + return syscall(__NR_futex_wake, uaddr, nr, flags); +} From patchwork Fri Jul 9 00:13:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472526 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59814C07E99 for ; Fri, 9 Jul 2021 00:14:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 42957611C2 for ; Fri, 9 Jul 2021 00:14:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230145AbhGIARR (ORCPT ); Thu, 8 Jul 2021 20:17:17 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44816 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230135AbhGIARQ (ORCPT ); Thu, 8 Jul 2021 20:17:16 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 5207F1F4198C From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 06/11] selftests: futex2: Add timeout test Date: Thu, 8 Jul 2021 21:13:23 -0300 Message-Id: <20210709001328.329716-7-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Adapt existing futex wait timeout file to test the same mechanism for futex2. futex2 accepts only absolute 64bit timers, but supports both monotonic and realtime clocks. Signed-off-by: André Almeida --- .../futex/functional/futex_wait_timeout.c | 24 +++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c index 1f8f6daaf1e7..d20f54745c2e 100644 --- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c +++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c @@ -17,6 +17,14 @@ #include #include "futextest.h" + +#include +#include +#include +#include +#include +#include +#include "futex2test.h" #include "logging.h" #define TEST_NAME "futex-wait-timeout" @@ -92,8 +100,8 @@ static int futex_get_abs_timeout(clockid_t clockid, struct timespec *to, int main(int argc, char *argv[]) { futex_t f1 = FUTEX_INITIALIZER; + struct timespec to = {.tv_sec = 0, .tv_nsec = timeout_ns}; int res, ret = RET_PASS; - struct timespec to; pthread_t thread; int c; @@ -118,7 +126,7 @@ int main(int argc, char *argv[]) } ksft_print_header(); - ksft_set_plan(7); + ksft_set_plan(9); ksft_print_msg("%s: Block on a futex and wait for timeout\n", basename(argv[0])); ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns); @@ -175,6 +183,18 @@ int main(int argc, char *argv[]) res = futex_lock_pi(&futex_pi, NULL, 0, FUTEX_CLOCK_REALTIME); test_timeout(res, &ret, "futex_lock_pi invalid timeout flag", ENOSYS); + /* setting absolute monotonic timeout for futex2 */ + if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns)) + return RET_FAIL; + res = futex2_wait(&f1, f1, FUTEX_32, &to); + test_timeout(res, &ret, "futex2_wait monotonic", ETIMEDOUT); + + /* setting absolute realtime timeout for futex2 */ + if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns)) + return RET_FAIL; + res = futex2_wait(&f1, f1, FUTEX_32 | FUTEX_CLOCK_REALTIME, &to); + test_timeout(res, &ret, "futex2_wait realtime", ETIMEDOUT); + ksft_print_cnts(); return ret; } From patchwork Fri Jul 9 00:13:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472105 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48B7FC07E99 for ; Fri, 9 Jul 2021 00:14:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3198B6113A for ; Fri, 9 Jul 2021 00:14:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229637AbhGIAR1 (ORCPT ); Thu, 8 Jul 2021 20:17:27 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44844 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230210AbhGIARX (ORCPT ); Thu, 8 Jul 2021 20:17:23 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id BBD551F41AF2 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 07/11] selftests: futex2: Add wouldblock test Date: Thu, 8 Jul 2021 21:13:24 -0300 Message-Id: <20210709001328.329716-8-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Adapt existing futex wait wouldblock file to test the same mechanism for futex2. Signed-off-by: André Almeida --- .../futex/functional/futex_wait_wouldblock.c | 33 ++++++++++++++++--- 1 file changed, 29 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/futex/functional/futex_wait_wouldblock.c b/tools/testing/selftests/futex/functional/futex_wait_wouldblock.c index 0ae390ff8164..510a98320248 100644 --- a/tools/testing/selftests/futex/functional/futex_wait_wouldblock.c +++ b/tools/testing/selftests/futex/functional/futex_wait_wouldblock.c @@ -12,6 +12,7 @@ * * HISTORY * 2009-Nov-14: Initial version by Gowrishankar + * 2021-Feb-5: Add futex2 test by André * *****************************************************************************/ @@ -21,7 +22,7 @@ #include #include #include -#include "futextest.h" +#include "futex2test.h" #include "logging.h" #define TEST_NAME "futex-wait-wouldblock" @@ -39,6 +40,7 @@ void usage(char *prog) int main(int argc, char *argv[]) { struct timespec to = {.tv_sec = 0, .tv_nsec = timeout_ns}; + struct timespec64 to64; futex_t f1 = FUTEX_INITIALIZER; int res, ret = RET_PASS; int c; @@ -61,18 +63,41 @@ int main(int argc, char *argv[]) } ksft_print_header(); - ksft_set_plan(1); + ksft_set_plan(2); ksft_print_msg("%s: Test the unexpected futex value in FUTEX_WAIT\n", basename(argv[0])); info("Calling futex_wait on f1: %u @ %p with val=%u\n", f1, &f1, f1+1); res = futex_wait(&f1, f1+1, &to, FUTEX_PRIVATE_FLAG); if (!res || errno != EWOULDBLOCK) { - fail("futex_wait returned: %d %s\n", + ksft_test_result_fail("futex_wait returned: %d %s\n", res ? errno : res, res ? strerror(errno) : ""); ret = RET_FAIL; + } else { + ksft_test_result_pass("futex_wait wouldblock\n"); } - print_result(TEST_NAME, ret); + /* setting absolute timeout for futex2 */ + if (gettime64(CLOCK_MONOTONIC, &to64)) + error("gettime64 failed\n", errno); + + to64.tv_nsec += timeout_ns; + + if (to64.tv_nsec >= 1000000000) { + to64.tv_sec++; + to64.tv_nsec -= 1000000000; + } + + info("Calling futex2_wait on f1: %u @ %p with val=%u\n", f1, &f1, f1+1); + res = futex2_wait(&f1, f1+1, FUTEX_32, &to64); + if (!res || errno != EWOULDBLOCK) { + ksft_test_result_fail("futex2_wait returned: %d %s\n", + res ? errno : res, res ? strerror(errno) : ""); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_wait wouldblock\n"); + } + + ksft_print_cnts(); return ret; } From patchwork Fri Jul 9 00:13:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472525 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B453C11F66 for ; Fri, 9 Jul 2021 00:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76D3C61464 for ; Fri, 9 Jul 2021 00:14:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230193AbhGIARb (ORCPT ); Thu, 8 Jul 2021 20:17:31 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44886 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230091AbhGIARa (ORCPT ); Thu, 8 Jul 2021 20:17:30 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 34CB71F41BA9 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 08/11] selftests: futex2: Add waitv test Date: Thu, 8 Jul 2021 21:13:25 -0300 Message-Id: <20210709001328.329716-9-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Create a new file to test the waitv mechanism. Test both private and shared futexes. Wake the last futex in the array, and check if the return value from futex_waitv() is the right index. Signed-off-by: André Almeida --- .../selftests/futex/functional/.gitignore | 1 + .../selftests/futex/functional/Makefile | 3 +- .../selftests/futex/functional/futex2_waitv.c | 154 ++++++++++++++++++ .../testing/selftests/futex/functional/run.sh | 3 + .../selftests/futex/include/futex2test.h | 17 ++ 5 files changed, 177 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/futex/functional/futex2_waitv.c diff --git a/tools/testing/selftests/futex/functional/.gitignore b/tools/testing/selftests/futex/functional/.gitignore index 3e2d577c0595..22c572de8d10 100644 --- a/tools/testing/selftests/futex/functional/.gitignore +++ b/tools/testing/selftests/futex/functional/.gitignore @@ -9,3 +9,4 @@ futex_wait_wouldblock futex_wait futex_requeue futex2_wait +futex2_waitv diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile index e4e4aa2e0368..240b53d8cb07 100644 --- a/tools/testing/selftests/futex/functional/Makefile +++ b/tools/testing/selftests/futex/functional/Makefile @@ -19,7 +19,8 @@ TEST_GEN_FILES := \ futex_wait_private_mapped_file \ futex_wait \ futex_requeue \ - futex2_wait + futex2_wait \ + futex2_waitv TEST_PROGS := run.sh diff --git a/tools/testing/selftests/futex/functional/futex2_waitv.c b/tools/testing/selftests/futex/functional/futex2_waitv.c new file mode 100644 index 000000000000..0f625a0657d5 --- /dev/null +++ b/tools/testing/selftests/futex/functional/futex2_waitv.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/****************************************************************************** + * + * Copyright Collabora Ltd., 2021 + * + * DESCRIPTION + * Test waitv/wake mechanism of futex2, using 32bit sized futexes. + * + * AUTHOR + * André Almeida + * + * HISTORY + * 2021-Feb-5: Initial version by André + * + *****************************************************************************/ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "futex2test.h" +#include "logging.h" + +#define TEST_NAME "futex2-wait" +#define WAKE_WAIT_US 10000 +#define NR_FUTEXES 30 +struct futex_waitv waitv[NR_FUTEXES]; +u_int32_t futexes[NR_FUTEXES] = {0}; + +void usage(char *prog) +{ + printf("Usage: %s\n", prog); + printf(" -c Use color\n"); + printf(" -h Display this help message\n"); + printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n", + VQUIET, VCRITICAL, VINFO); +} + +void *waiterfn(void *arg) +{ + struct timespec64 to64; + int res; + + /* setting absolute timeout for futex2 */ + if (gettime64(CLOCK_MONOTONIC, &to64)) + error("gettime64 failed\n", errno); + + to64.tv_sec++; + + res = futex2_waitv(waitv, NR_FUTEXES, 0, &to64); + if (res < 0) { + ksft_test_result_fail("futex2_waitv returned: %d %s\n", + errno, strerror(errno)); + } else if (res != NR_FUTEXES - 1) { + ksft_test_result_fail("futex2_waitv returned: %d, expecting %d\n", + res, NR_FUTEXES - 1); + } + + return NULL; +} + +int main(int argc, char *argv[]) +{ + pthread_t waiter; + int res, ret = RET_PASS; + int c, i; + + while ((c = getopt(argc, argv, "cht:v:")) != -1) { + switch (c) { + case 'c': + log_color(1); + break; + case 'h': + usage(basename(argv[0])); + exit(0); + case 'v': + log_verbosity(atoi(optarg)); + break; + default: + usage(basename(argv[0])); + exit(1); + } + } + + ksft_print_header(); + ksft_set_plan(2); + ksft_print_msg("%s: Test FUTEX2_WAITV\n", + basename(argv[0])); + + for (i = 0; i < NR_FUTEXES; i++) { + waitv[i].uaddr = &futexes[i]; + waitv[i].flags = FUTEX_32; + waitv[i].val = 0; + } + + /* Private waitv */ + if (pthread_create(&waiter, NULL, waiterfn, NULL)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + res = futex2_wake(waitv[NR_FUTEXES - 1].uaddr, 1, FUTEX_32); + if (res != 1) { + ksft_test_result_fail("futex2_waitv private returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_waitv private\n"); + } + + /* Shared waitv */ + for (i = 0; i < NR_FUTEXES; i++) { + int shm_id = shmget(IPC_PRIVATE, 4096, IPC_CREAT | 0666); + + if (shm_id < 0) { + perror("shmget"); + exit(1); + } + + unsigned int *shared_data = shmat(shm_id, NULL, 0); + + *shared_data = 0; + waitv[i].uaddr = shared_data; + waitv[i].flags = FUTEX_32 | FUTEX_SHARED_FLAG; + waitv[i].val = 0; + } + + if (pthread_create(&waiter, NULL, waiterfn, NULL)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + res = futex2_wake(waitv[NR_FUTEXES - 1].uaddr, 1, FUTEX_32 | FUTEX_SHARED_FLAG); + if (res != 1) { + ksft_test_result_fail("futex2_waitv shared returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_waitv shared\n"); + } + + for (i = 0; i < NR_FUTEXES; i++) + shmdt(waitv[i].uaddr); + + ksft_print_cnts(); + return ret; +} diff --git a/tools/testing/selftests/futex/functional/run.sh b/tools/testing/selftests/futex/functional/run.sh index dbe82275617c..6d30a30547da 100755 --- a/tools/testing/selftests/futex/functional/run.sh +++ b/tools/testing/selftests/futex/functional/run.sh @@ -82,3 +82,6 @@ echo echo ./futex2_wait $COLOR + +echo +./futex2_waitv $COLOR diff --git a/tools/testing/selftests/futex/include/futex2test.h b/tools/testing/selftests/futex/include/futex2test.h index e724d56b917e..0ed3b20935be 100644 --- a/tools/testing/selftests/futex/include/futex2test.h +++ b/tools/testing/selftests/futex/include/futex2test.h @@ -28,6 +28,10 @@ # define FUTEX_32 2 #endif +#ifndef FUTEX_SHARED_FLAG +#define FUTEX_SHARED_FLAG 8 +#endif + /* * - Y2038 section for 32-bit applications - * @@ -77,3 +81,16 @@ static inline int futex2_wake(volatile void *uaddr, unsigned int nr, unsigned lo { return syscall(__NR_futex_wake, uaddr, nr, flags); } + +/** + * futex2_waitv - Wait at multiple futexes, wake on any + * @waiters: Array of waiters + * @nr_waiters: Length of waiters array + * @flags: Operation flags + * @timo: Optional timeout for operation + */ +static inline int futex2_waitv(volatile struct futex_waitv *waiters, unsigned long nr_waiters, + unsigned long flags, struct timespec64 *timo) +{ + return syscall(__NR_futex_waitv, waiters, nr_waiters, flags, timo); +} From patchwork Fri Jul 9 00:13:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472104 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC07FC07E96 for ; Fri, 9 Jul 2021 00:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3F126146B for ; Fri, 9 Jul 2021 00:14:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230280AbhGIARj (ORCPT ); Thu, 8 Jul 2021 20:17:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230130AbhGIARh (ORCPT ); Thu, 8 Jul 2021 20:17:37 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2ADB2C061764; Thu, 8 Jul 2021 17:14:54 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 996E21F433BD From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 09/11] selftests: futex2: Add requeue test Date: Thu, 8 Jul 2021 21:13:26 -0300 Message-Id: <20210709001328.329716-10-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add testing for futex_requeue(). The first test just requeue from one waiter to another one, and wake it. The second performs both wake and requeue, and we check return values to see if the operation woke/requeued the expected number of waiters. Signed-off-by: André Almeida --- .../selftests/futex/functional/.gitignore | 1 + .../selftests/futex/functional/Makefile | 3 +- .../futex/functional/futex2_requeue.c | 164 ++++++++++++++++++ .../selftests/futex/include/futex2test.h | 16 ++ 4 files changed, 183 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/futex/functional/futex2_requeue.c diff --git a/tools/testing/selftests/futex/functional/.gitignore b/tools/testing/selftests/futex/functional/.gitignore index 22c572de8d10..d63b5f74bd6f 100644 --- a/tools/testing/selftests/futex/functional/.gitignore +++ b/tools/testing/selftests/futex/functional/.gitignore @@ -10,3 +10,4 @@ futex_wait futex_requeue futex2_wait futex2_waitv +futex2_requeue diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile index 240b53d8cb07..e162e40ce38f 100644 --- a/tools/testing/selftests/futex/functional/Makefile +++ b/tools/testing/selftests/futex/functional/Makefile @@ -20,7 +20,8 @@ TEST_GEN_FILES := \ futex_wait \ futex_requeue \ futex2_wait \ - futex2_waitv + futex2_waitv \ + futex2_requeue TEST_PROGS := run.sh diff --git a/tools/testing/selftests/futex/functional/futex2_requeue.c b/tools/testing/selftests/futex/functional/futex2_requeue.c new file mode 100644 index 000000000000..1bc3704dc8c2 --- /dev/null +++ b/tools/testing/selftests/futex/functional/futex2_requeue.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/****************************************************************************** + * + * Copyright Collabora Ltd., 2021 + * + * DESCRIPTION + * Test requeue mechanism of futex2, using 32bit sized futexes. + * + * AUTHOR + * André Almeida + * + * HISTORY + * 2021-Feb-5: Initial version by André + * + *****************************************************************************/ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "futex2test.h" +#include "logging.h" + +#define TEST_NAME "futex2-wait" +#define timeout_ns 30000000 +#define WAKE_WAIT_US 10000 +volatile futex_t *f1; + +void usage(char *prog) +{ + printf("Usage: %s\n", prog); + printf(" -c Use color\n"); + printf(" -h Display this help message\n"); + printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n", + VQUIET, VCRITICAL, VINFO); +} + +void *waiterfn(void *arg) +{ + struct timespec64 to64; + + /* setting absolute timeout for futex2 */ + if (gettime64(CLOCK_MONOTONIC, &to64)) + error("gettime64 failed\n", errno); + + to64.tv_nsec += timeout_ns; + + if (to64.tv_nsec >= 1000000000) { + to64.tv_sec++; + to64.tv_nsec -= 1000000000; + } + + if (futex2_wait(f1, *f1, FUTEX_32, &to64)) + printf("waiter failed errno %d\n", errno); + + return NULL; +} + +int main(int argc, char *argv[]) +{ + pthread_t waiter[10]; + int res, ret = RET_PASS; + int c, i; + volatile futex_t _f1 = 0; + volatile futex_t f2 = 0; + struct futex_requeue r1, r2; + + f1 = &_f1; + + r1.flags = FUTEX_32; + r2.flags = FUTEX_32; + + r1.uaddr = f1; + r2.uaddr = &f2; + + while ((c = getopt(argc, argv, "cht:v:")) != -1) { + switch (c) { + case 'c': + log_color(1); + break; + case 'h': + usage(basename(argv[0])); + exit(0); + case 'v': + log_verbosity(atoi(optarg)); + break; + default: + usage(basename(argv[0])); + exit(1); + } + } + + ksft_print_header(); + ksft_set_plan(2); + ksft_print_msg("%s: Test FUTEX2_REQUEUE\n", + basename(argv[0])); + + /* + * Requeue a waiter from f1 to f2, and wake f2. + */ + if (pthread_create(&waiter[0], NULL, waiterfn, NULL)) + error("pthread_create failed\n", errno); + + usleep(WAKE_WAIT_US); + + res = futex2_requeue(&r1, &r2, 0, 1, 0, 0); + if (res != 1) { + ksft_test_result_fail("futex2_requeue private returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } + + + info("Calling private futex2_wake on f2: %u @ %p with val=%u\n", f2, &f2, f2); + res = futex2_wake(&f2, 1, FUTEX_32); + if (res != 1) { + ksft_test_result_fail("futex2_requeue private returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_requeue simple succeeds\n"); + } + + + /* + * Create 10 waiters at f1. At futex_requeue, wake 3 and requeue 7. + * At futex_wake, wake INT_MAX (should be exaclty 7). + */ + for (i = 0; i < 10; i++) { + if (pthread_create(&waiter[i], NULL, waiterfn, NULL)) + error("pthread_create failed\n", errno); + } + + usleep(WAKE_WAIT_US); + + res = futex2_requeue(&r1, &r2, 3, 7, 0, 0); + if (res != 10) { + ksft_test_result_fail("futex2_requeue private returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } + + res = futex2_wake(&f2, INT_MAX, FUTEX_32); + if (res != 7) { + ksft_test_result_fail("futex2_requeue private returned: %d %s\n", + res ? errno : res, + res ? strerror(errno) : ""); + ret = RET_FAIL; + } else { + ksft_test_result_pass("futex2_requeue succeeds\n"); + } + + ksft_print_cnts(); + return ret; +} diff --git a/tools/testing/selftests/futex/include/futex2test.h b/tools/testing/selftests/futex/include/futex2test.h index 0ed3b20935be..682ba8319590 100644 --- a/tools/testing/selftests/futex/include/futex2test.h +++ b/tools/testing/selftests/futex/include/futex2test.h @@ -94,3 +94,19 @@ static inline int futex2_waitv(volatile struct futex_waitv *waiters, unsigned lo { return syscall(__NR_futex_waitv, waiters, nr_waiters, flags, timo); } + +/** + * futex2_requeue - Wake futexes at uaddr1 and requeue from uaddr1 to uaddr2 + * @uaddr1: Original address to wake and requeue from + * @uaddr2: Address to requeue to + * @nr_wake: Number of futexes to wake at uaddr1 before requeuing + * @nr_requeue: Number of futexes to requeue from uaddr1 to uaddr2 + * @cmpval: If (uaddr1->uaddr != cmpval), return immediatally + * @flgas: Operation flags + */ +static inline int futex2_requeue(struct futex_requeue *rq1, struct futex_requeue *rq2, + unsigned int nr_wake, unsigned int nr_requeue, + unsigned int cmpval, unsigned long flags) +{ + return syscall(__NR_futex_requeue, rq1, rq2, nr_wake, nr_requeue, cmpval, flags); +} From patchwork Fri Jul 9 00:13:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472524 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 738EFC07E96 for ; Fri, 9 Jul 2021 00:15:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A9B6611C2 for ; Fri, 9 Jul 2021 00:15:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230352AbhGIARn (ORCPT ); Thu, 8 Jul 2021 20:17:43 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44946 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230336AbhGIARn (ORCPT ); Thu, 8 Jul 2021 20:17:43 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id 3716A1F41DE0 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 10/11] perf bench: Add futex2 benchmark tests Date: Thu, 8 Jul 2021 21:13:27 -0300 Message-Id: <20210709001328.329716-11-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add support at the existing futex benchmarking code base to enable futex2 calls. `perf bench` tests can be used not only as a way to measure the performance of implementation, but also as stress testing for the kernel infrastructure. Signed-off-by: André Almeida --- tools/arch/x86/include/asm/unistd_64.h | 12 ++++++ tools/perf/bench/bench.h | 4 ++ tools/perf/bench/futex-hash.c | 24 +++++++++-- tools/perf/bench/futex-requeue.c | 57 ++++++++++++++++++++------ tools/perf/bench/futex-wake-parallel.c | 41 +++++++++++++++--- tools/perf/bench/futex-wake.c | 37 +++++++++++++---- tools/perf/bench/futex.h | 47 +++++++++++++++++++++ tools/perf/builtin-bench.c | 18 ++++++-- 8 files changed, 206 insertions(+), 34 deletions(-) diff --git a/tools/arch/x86/include/asm/unistd_64.h b/tools/arch/x86/include/asm/unistd_64.h index 4205ed4158bf..191d43d84f04 100644 --- a/tools/arch/x86/include/asm/unistd_64.h +++ b/tools/arch/x86/include/asm/unistd_64.h @@ -17,3 +17,15 @@ #ifndef __NR_setns #define __NR_setns 308 #endif + +#ifndef __NR_futex_wait +# define __NR_futex_wait 447 +#endif + +#ifndef __NR_futex_wake +# define __NR_futex_wake 448 +#endif + +#ifndef __NR_futex_requeue +# define __NR_futex_requeue 450 +#endif diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h index eac36afab2b3..12346844b354 100644 --- a/tools/perf/bench/bench.h +++ b/tools/perf/bench/bench.h @@ -38,9 +38,13 @@ int bench_mem_memcpy(int argc, const char **argv); int bench_mem_memset(int argc, const char **argv); int bench_mem_find_bit(int argc, const char **argv); int bench_futex_hash(int argc, const char **argv); +int bench_futex2_hash(int argc, const char **argv); int bench_futex_wake(int argc, const char **argv); +int bench_futex2_wake(int argc, const char **argv); int bench_futex_wake_parallel(int argc, const char **argv); +int bench_futex2_wake_parallel(int argc, const char **argv); int bench_futex_requeue(int argc, const char **argv); +int bench_futex2_requeue(int argc, const char **argv); /* pi futexes */ int bench_futex_lock_pi(int argc, const char **argv); int bench_epoll_wait(int argc, const char **argv); diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c index b65373ce5c4f..1068749af40c 100644 --- a/tools/perf/bench/futex-hash.c +++ b/tools/perf/bench/futex-hash.c @@ -33,7 +33,7 @@ static unsigned int nthreads = 0; static unsigned int nsecs = 10; /* amount of futexes per thread */ static unsigned int nfutexes = 1024; -static bool fshared = false, done = false, silent = false; +static bool fshared = false, done = false, silent = false, futex2 = false; static int futex_flag = 0; struct timeval bench__start, bench__end, bench__runtime; @@ -85,7 +85,10 @@ static void *workerfn(void *arg) * such as internal waitqueue handling, thus enlarging * the critical region protected by hb->lock. */ - ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); + if (!futex2) + ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); + else + ret = futex2_wait(&w->futex[i], 1234, futex_flag, NULL); if (!silent && (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) warn("Non-expected futex return call"); @@ -116,7 +119,7 @@ static void print_summary(void) (int)bench__runtime.tv_sec); } -int bench_futex_hash(int argc, const char **argv) +static int __bench_futex_hash(int argc, const char **argv) { int ret = 0; cpu_set_t cpuset; @@ -148,7 +151,9 @@ int bench_futex_hash(int argc, const char **argv) if (!worker) goto errmem; - if (!fshared) + if (futex2) + futex_flag = FUTEX_32 | (fshared * FUTEX_SHARED_FLAG); + else if (!fshared) futex_flag = FUTEX_PRIVATE_FLAG; printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", @@ -228,3 +233,14 @@ int bench_futex_hash(int argc, const char **argv) errmem: err(EXIT_FAILURE, "calloc"); } + +int bench_futex_hash(int argc, const char **argv) +{ + return __bench_futex_hash(argc, argv); +} + +int bench_futex2_hash(int argc, const char **argv) +{ + futex2 = true; + return __bench_futex_hash(argc, argv); +} diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c index 5fa23295ee5f..ee5e0da5ba50 100644 --- a/tools/perf/bench/futex-requeue.c +++ b/tools/perf/bench/futex-requeue.c @@ -2,8 +2,8 @@ /* * Copyright (C) 2013 Davidlohr Bueso * - * futex-requeue: Block a bunch of threads on futex1 and requeue them - * on futex2, N at a time. + * futex-requeue: Block a bunch of threads on addr1 and requeue them + * on addr2, N at a time. * * This program is particularly useful to measure the latency of nthread * requeues without waking up any tasks -- thus mimicking a regular futex_wait. @@ -28,7 +28,10 @@ #include #include -static u_int32_t futex1 = 0, futex2 = 0; +static u_int32_t addr1 = 0, addr2 = 0; + +static struct futex_requeue rq1 = { .uaddr = &addr1, .flags = FUTEX_32 }; +static struct futex_requeue rq2 = { .uaddr = &addr2, .flags = FUTEX_32 }; /* * How many tasks to requeue at a time. @@ -37,7 +40,7 @@ static u_int32_t futex1 = 0, futex2 = 0; static unsigned int nrequeue = 1; static pthread_t *worker; -static bool done = false, silent = false, fshared = false; +static bool done = false, silent = false, fshared = false, futex2 = false; static pthread_mutex_t thread_lock; static pthread_cond_t thread_parent, thread_worker; static struct stats requeuetime_stats, requeued_stats; @@ -79,7 +82,11 @@ static void *workerfn(void *arg __maybe_unused) pthread_cond_wait(&thread_worker, &thread_lock); pthread_mutex_unlock(&thread_lock); - futex_wait(&futex1, 0, NULL, futex_flag); + if (!futex2) + futex_wait(&addr1, 0, NULL, futex_flag); + else + futex2_wait(&addr1, 0, futex_flag, NULL); + return NULL; } @@ -111,7 +118,7 @@ static void toggle_done(int sig __maybe_unused, done = true; } -int bench_futex_requeue(int argc, const char **argv) +static int __bench_futex_requeue(int argc, const char **argv) { int ret = 0; unsigned int i, j; @@ -139,15 +146,20 @@ int bench_futex_requeue(int argc, const char **argv) if (!worker) err(EXIT_FAILURE, "calloc"); - if (!fshared) + if (futex2) { + futex_flag = FUTEX_32 | (fshared * FUTEX_SHARED_FLAG); + rq1.flags |= FUTEX_SHARED_FLAG * fshared; + rq2.flags |= FUTEX_SHARED_FLAG * fshared; + } else if (!fshared) { futex_flag = FUTEX_PRIVATE_FLAG; + } if (nrequeue > nthreads) nrequeue = nthreads; printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %p), " "%d at a time.\n\n", getpid(), nthreads, - fshared ? "shared":"private", &futex1, &futex2, nrequeue); + fshared ? "shared":"private", &addr1, &addr2, nrequeue); init_stats(&requeued_stats); init_stats(&requeuetime_stats); @@ -176,11 +188,15 @@ int bench_futex_requeue(int argc, const char **argv) gettimeofday(&start, NULL); while (nrequeued < nthreads) { /* - * Do not wakeup any tasks blocked on futex1, allowing + * Do not wakeup any tasks blocked on addr1, allowing * us to really measure futex_wait functionality. */ - nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0, - nrequeue, futex_flag); + if (!futex2) + nrequeued += futex_cmp_requeue(&addr1, 0, &addr2, + 0, nrequeue, futex_flag); + else + nrequeued += futex2_requeue(&rq1, &rq2, + 0, nrequeue, 0, 0); } gettimeofday(&end, NULL); @@ -194,8 +210,12 @@ int bench_futex_requeue(int argc, const char **argv) j + 1, nrequeued, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC); } - /* everybody should be blocked on futex2, wake'em up */ - nrequeued = futex_wake(&futex2, nrequeued, futex_flag); + /* everybody should be blocked on addr2, wake'em up */ + if (!futex2) + nrequeued = futex_wake(&addr2, nrequeued, futex_flag); + else + nrequeued = futex2_wake(&addr2, nrequeued, futex_flag); + if (nthreads != nrequeued) warnx("couldn't wakeup all tasks (%d/%d)", nrequeued, nthreads); @@ -220,3 +240,14 @@ int bench_futex_requeue(int argc, const char **argv) usage_with_options(bench_futex_requeue_usage, options); exit(EXIT_FAILURE); } + +int bench_futex_requeue(int argc, const char **argv) +{ + return __bench_futex_requeue(argc, argv); +} + +int bench_futex2_requeue(int argc, const char **argv) +{ + futex2 = true; + return __bench_futex_requeue(argc, argv); +} diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c index 6e6f5247e1fe..cac90fc0bfb3 100644 --- a/tools/perf/bench/futex-wake-parallel.c +++ b/tools/perf/bench/futex-wake-parallel.c @@ -17,6 +17,12 @@ int bench_futex_wake_parallel(int argc __maybe_unused, const char **argv __maybe pr_err("%s: pthread_barrier_t unavailable, disabling this test...\n", __func__); return 0; } + +int bench_futex2_wake_parallel(int argc __maybe_unused, const char **argv __maybe_unused) +{ + pr_err("%s: pthread_barrier_t unavailable, disabling this test...\n", __func__); + return 0; +} #else /* HAVE_PTHREAD_BARRIER */ /* For the CLR_() macros */ #include @@ -47,7 +53,7 @@ static unsigned int nwakes = 1; static u_int32_t futex = 0; static pthread_t *blocked_worker; -static bool done = false, silent = false, fshared = false; +static bool done = false, silent = false, fshared = false, futex2 = false; static unsigned int nblocked_threads = 0, nwaking_threads = 0; static pthread_mutex_t thread_lock; static pthread_cond_t thread_parent, thread_worker; @@ -78,7 +84,11 @@ static void *waking_workerfn(void *arg) gettimeofday(&start, NULL); - waker->nwoken = futex_wake(&futex, nwakes, futex_flag); + if (!futex2) + waker->nwoken = futex_wake(&futex, nwakes, futex_flag); + else + waker->nwoken = futex2_wake(&futex, nwakes, futex_flag); + if (waker->nwoken != nwakes) warnx("couldn't wakeup all tasks (%d/%d)", waker->nwoken, nwakes); @@ -129,8 +139,13 @@ static void *blocked_workerfn(void *arg __maybe_unused) pthread_mutex_unlock(&thread_lock); while (1) { /* handle spurious wakeups */ - if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR) - break; + if (!futex2) { + if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR) + break; + } else { + if (futex2_wait(&futex, 0, futex_flag, NULL) != EINTR) + break; + } } pthread_exit(NULL); @@ -217,7 +232,7 @@ static void toggle_done(int sig __maybe_unused, done = true; } -int bench_futex_wake_parallel(int argc, const char **argv) +static int __bench_futex_wake_parallel(int argc, const char **argv) { int ret = 0; unsigned int i, j; @@ -261,7 +276,9 @@ int bench_futex_wake_parallel(int argc, const char **argv) if (!blocked_worker) err(EXIT_FAILURE, "calloc"); - if (!fshared) + if (futex2) + futex_flag = FUTEX_32 | (fshared * FUTEX_SHARED_FLAG); + else if (!fshared) futex_flag = FUTEX_PRIVATE_FLAG; printf("Run summary [PID %d]: blocking on %d threads (at [%s] " @@ -321,4 +338,16 @@ int bench_futex_wake_parallel(int argc, const char **argv) free(blocked_worker); return ret; } + +int bench_futex_wake_parallel(int argc, const char **argv) +{ + return __bench_futex_wake_parallel(argc, argv); +} + +int bench_futex2_wake_parallel(int argc, const char **argv) +{ + futex2 = true; + return __bench_futex_wake_parallel(argc, argv); +} + #endif /* HAVE_PTHREAD_BARRIER */ diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c index 6d217868f53c..546d2818eed8 100644 --- a/tools/perf/bench/futex-wake.c +++ b/tools/perf/bench/futex-wake.c @@ -38,7 +38,7 @@ static u_int32_t futex1 = 0; static unsigned int nwakes = 1; pthread_t *worker; -static bool done = false, silent = false, fshared = false; +static bool done = false, silent = false, fshared = false, futex2 = false; static pthread_mutex_t thread_lock; static pthread_cond_t thread_parent, thread_worker; static struct stats waketime_stats, wakeup_stats; @@ -68,8 +68,13 @@ static void *workerfn(void *arg __maybe_unused) pthread_mutex_unlock(&thread_lock); while (1) { - if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR) - break; + if (!futex2) { + if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR) + break; + } else { + if (futex2_wait(&futex1, 0, futex_flag, NULL) != EINTR) + break; + } } pthread_exit(NULL); @@ -117,7 +122,7 @@ static void toggle_done(int sig __maybe_unused, done = true; } -int bench_futex_wake(int argc, const char **argv) +static int __bench_futex_wake(int argc, const char **argv) { int ret = 0; unsigned int i, j; @@ -147,7 +152,9 @@ int bench_futex_wake(int argc, const char **argv) if (!worker) err(EXIT_FAILURE, "calloc"); - if (!fshared) + if (futex2) + futex_flag = FUTEX_32 | (fshared * FUTEX_SHARED_FLAG); + else if (!fshared) futex_flag = FUTEX_PRIVATE_FLAG; printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), " @@ -179,9 +186,14 @@ int bench_futex_wake(int argc, const char **argv) /* Ok, all threads are patiently blocked, start waking folks up */ gettimeofday(&start, NULL); - while (nwoken != nthreads) - nwoken += futex_wake(&futex1, nwakes, futex_flag); + while (nwoken != nthreads) { + if (!futex2) + nwoken += futex_wake(&futex1, nwakes, futex_flag); + else + nwoken += futex2_wake(&futex1, nwakes, futex_flag); + } gettimeofday(&end, NULL); + timersub(&end, &start, &runtime); update_stats(&wakeup_stats, nwoken); @@ -211,3 +223,14 @@ int bench_futex_wake(int argc, const char **argv) free(worker); return ret; } + +int bench_futex_wake(int argc, const char **argv) +{ + return __bench_futex_wake(argc, argv); +} + +int bench_futex2_wake(int argc, const char **argv) +{ + futex2 = true; + return __bench_futex_wake(argc, argv); +} diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h index 31b53cc7d5bc..6b2213cf3f64 100644 --- a/tools/perf/bench/futex.h +++ b/tools/perf/bench/futex.h @@ -86,4 +86,51 @@ futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wak return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2, val, opflags); } + +/** + * futex2_wait - Wait at uaddr if *uaddr == val, until timo. + * @uaddr: User address to wait for + * @val: Expected value at uaddr + * @flags: Operation options + * @timo: Optional timeout + * + * Return: 0 on success, error code otherwise + */ +static inline int futex2_wait(volatile void *uaddr, unsigned long val, + unsigned long flags, struct timespec *timo) +{ + return syscall(__NR_futex_wait, uaddr, val, flags, timo); +} + +/** + * futex2_wake - Wake a number of waiters waiting at uaddr + * @uaddr: Address to wake + * @nr: Number of waiters to wake + * @flags: Operation options + * + * Return: number of waked futexes + */ +static inline int futex2_wake(volatile void *uaddr, unsigned int nr, unsigned long flags) +{ + return syscall(__NR_futex_wake, uaddr, nr, flags); +} + +/** + * futex2_requeue - Requeue waiters from an address to another one + * @uaddr1: Address where waiters are currently waiting on + * @uaddr2: New address to wait + * @nr_wake: Number of waiters at uaddr1 to be wake + * @nr_requeue: After waking nr_wake, number of waiters to be requeued + * @cmpval: Expected value at uaddr1 + * @flags: Operation options + * + * Return: waked futexes + requeued futexes at uaddr1 + */ +static inline int futex2_requeue(volatile struct futex_requeue *uaddr1, + volatile struct futex_requeue *uaddr2, + unsigned int nr_wake, unsigned int nr_requeue, + unsigned int cmpval, unsigned long flags) +{ + return syscall(__NR_futex_requeue, uaddr1, uaddr2, nr_wake, nr_requeue, cmpval, flags); +} #endif /* _FUTEX_H */ diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c index 62a7b7420a44..e41a95ad2db6 100644 --- a/tools/perf/builtin-bench.c +++ b/tools/perf/builtin-bench.c @@ -12,10 +12,11 @@ * * sched ... scheduler and IPC performance * syscall ... System call performance - * mem ... memory access performance - * numa ... NUMA scheduling and MM performance - * futex ... Futex performance - * epoll ... Event poll performance + * mem ... memory access performance + * numa ... NUMA scheduling and MM performance + * futex ... Futex performance + * futex2 ... Futex2 performance + * epoll ... Event poll performance */ #include #include "builtin.h" @@ -75,6 +76,14 @@ static struct bench futex_benchmarks[] = { { NULL, NULL, NULL } }; +static struct bench futex2_benchmarks[] = { + { "hash", "Benchmark for futex2 hash table", bench_futex2_hash }, + { "wake", "Benchmark for futex2 wake calls", bench_futex2_wake }, + { "wake-parallel", "Benchmark for parallel futex2 wake calls", bench_futex2_wake_parallel }, + { "requeue", "Benchmark for futex2 requeue calls", bench_futex2_requeue }, + { NULL, NULL, NULL } +}; + #ifdef HAVE_EVENTFD_SUPPORT static struct bench epoll_benchmarks[] = { { "wait", "Benchmark epoll concurrent epoll_waits", bench_epoll_wait }, @@ -105,6 +114,7 @@ static struct collection collections[] = { { "numa", "NUMA scheduling and MM benchmarks", numa_benchmarks }, #endif {"futex", "Futex stressing benchmarks", futex_benchmarks }, + {"futex2", "Futex2 stressing benchmarks", futex2_benchmarks }, #ifdef HAVE_EVENTFD_SUPPORT {"epoll", "Epoll stressing benchmarks", epoll_benchmarks }, #endif From patchwork Fri Jul 9 00:13:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 472103 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EC77C07E9C for ; Fri, 9 Jul 2021 00:15:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0E2A6146B for ; Fri, 9 Jul 2021 00:15:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230404AbhGIARw (ORCPT ); Thu, 8 Jul 2021 20:17:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230262AbhGIARt (ORCPT ); Thu, 8 Jul 2021 20:17:49 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE64EC061760; Thu, 8 Jul 2021 17:15:06 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tonyk) with ESMTPSA id AD5281F41E36 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-kernel@vger.kernel.org, Steven Rostedt , Sebastian Andrzej Siewior Cc: kernel@collabora.com, krisman@collabora.com, pgriffais@valvesoftware.com, z.figura12@gmail.com, joel@joelfernandes.org, malteskarupke@fastmail.fm, linux-api@vger.kernel.org, fweimer@redhat.com, libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, acme@kernel.org, corbet@lwn.net, Peter Oskolkov , Andrey Semashev , Davidlohr Bueso , Nicholas Piggin , Adhemerval Zanella , =?utf-8?q?Andr=C3=A9_Almeida?= Subject: [PATCH v5 11/11] kernel: Enable waitpid() for futex2 Date: Thu, 8 Jul 2021 21:13:28 -0300 Message-Id: <20210709001328.329716-12-andrealmeid@collabora.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709001328.329716-1-andrealmeid@collabora.com> References: <20210709001328.329716-1-andrealmeid@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org To make pthreads works as expected if they are using futex2, wake clear_child_tid with futex2 as well. This is make applications that uses waitpid() (and clone(CLONE_CHILD_SETTID)) wake while waiting for the child to terminate. Given that apps should not mix futex() and futex2(), any correct app will trigger a harmless noop wakeup on the interface that it isn't using. Signed-off-by: André Almeida --- This commit is here for the intend to show what we need to do in order to get a full NPTL working on top of futex2. It should be merged after we talk to glibc folks on the details around the futex_wait() side. For instance, we could use this as an opportunity to use private futexes or 8bit sized futexes, but both sides need to use the exactly same flags. --- include/linux/syscalls.h | 2 ++ kernel/fork.c | 2 ++ kernel/futex2.c | 30 ++++++++++++++++++------------ 3 files changed, 22 insertions(+), 12 deletions(-) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index b9c2874410d0..85b5a501fb96 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1315,6 +1315,8 @@ int ksys_ipc(unsigned int call, int first, unsigned long second, unsigned long third, void __user * ptr, long fifth); int compat_ksys_ipc(u32 call, int first, int second, u32 third, u32 ptr, u32 fifth); +long ksys_futex_wake(void __user *uaddr, unsigned int nr_wake, + unsigned int flags); /* * The following kernel syscall equivalents are just wrappers to fs-internal diff --git a/kernel/fork.c b/kernel/fork.c index b4386ff6a641..f3f98e197fb6 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1328,6 +1328,8 @@ static void mm_release(struct task_struct *tsk, struct mm_struct *mm) put_user(0, tsk->clear_child_tid); do_futex(tsk->clear_child_tid, FUTEX_WAKE, 1, NULL, NULL, 0, 0); + ksys_futex_wake(tsk->clear_child_tid, 1, + FUTEX_32 | FUTEX_SHARED_FLAG); } tsk->clear_child_tid = NULL; } diff --git a/kernel/futex2.c b/kernel/futex2.c index 4f6d099badec..2ca2f40fcdd2 100644 --- a/kernel/futex2.c +++ b/kernel/futex2.c @@ -420,18 +420,8 @@ COMPAT_SYSCALL_DEFINE4(futex_wait, void __user *, uaddr, compat_u64, val, } #endif -/** - * sys_futex_wake - Wake a number of futexes waiting on an address - * @uaddr: Address of futex to be woken up - * @nr_wake: Number of futexes waiting in uaddr to be woken up - * @flags: Flags for size and shared - * - * Wake `nr_wake` threads waiting at uaddr. - * - * Returns the number of woken threads on success, error code otherwise. - */ -SYSCALL_DEFINE3(futex_wake, void __user *, uaddr, unsigned int, nr_wake, - unsigned int, flags) +long ksys_futex_wake(void __user *uaddr, unsigned int nr_wake, + unsigned int flags) { unsigned int size = flags & FUTEX_SIZE_MASK, futex_flags = 0; @@ -447,6 +437,22 @@ SYSCALL_DEFINE3(futex_wake, void __user *, uaddr, unsigned int, nr_wake, return futex_wake(uaddr, futex_flags, nr_wake, FUTEX_BITSET_MATCH_ANY); } +/** + * sys_futex_wake - Wake a number of futexes waiting on an address + * @uaddr: Address of futex to be woken up + * @nr_wake: Number of futexes waiting in uaddr to be woken up + * @flags: Flags for size and shared + * + * Wake `nr_wake` threads waiting at uaddr. + * + * Returns the number of woken threads on success, error code otherwise. + */ +SYSCALL_DEFINE3(futex_wake, void __user *, uaddr, unsigned int, nr_wake, + unsigned int, flags) +{ + return ksys_futex_wake(uaddr, nr_wake, flags); +} + #ifdef CONFIG_COMPAT static int compat_futex_parse_requeue(struct compat_futex_requeue __user *rq, void __user **uaddr, unsigned int *flags)