From patchwork Fri Oct 6 13:34:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 115066 Delivered-To: patch@linaro.org Received: by 10.80.163.170 with SMTP id s39csp1376272edb; Fri, 6 Oct 2017 06:35:15 -0700 (PDT) X-Google-Smtp-Source: AOwi7QDRaVDa+7OCXdyDr8yewbKTNQsQrlFr6LXinaMrzqVDHkbmzCWD618xFuaIKZPYh327zAeI X-Received: by 10.99.155.26 with SMTP id r26mr2055724pgd.139.1507296915677; Fri, 06 Oct 2017 06:35:15 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507296915; cv=none; d=google.com; s=arc-20160816; b=mqHAWM34GAQaVCJFYR5Ehl+XTRw3D7QikOLShacasE4gFf2a7fj7y/xXWYW75FNzOY YnVYgwMbdJvJ8qpupd42QC7h/ogzo/GzPsZP00WX3olC5kfX2wzYh+C2U/Df44o3TbOQ 41v8aKuvaoZJ6sl+fGGa71fF2GFWTjmuJXUf6cKC489U74jI7rfPxKCS4zvLsF1BCzTd wMFp1bODFC+mpyQ+rl/zkytCu1HP2pA8mfnX6ty1+iZTzdnxIqXZpRzl8h+8031LQv8V WDMz1Rufnj/nvxCYzdlep5Lt+8G4UvMHxG/FoN3157HRUKXz60xUdD1aGwfq7DUBLWEF df4Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=w7TWWYNyuCNcNGH1mif+F9tnZIJtaXKDG3iGHaIC/Rg=; b=c0PsJzntjdi+WvzSjkMi6JiTFeQQwsOHPF1W34JrHVA3QE96LykbDFna8LZxX+myVX 1WAq2Ualhe/OL7GBO0guPsSL7gjisQDUos2dpEZNAwMQvvEXrZc1mJRF7QC22c5IaGQS vK1GjEozTViUS8QSvUEefDA0tir6p0zzIUY8m0TseOGaFaxc4UVcQnyOZc0TbmYr33Fc CG6CUnxYG0yt4+Kg+OkW//0UNPjr8p7jpv3O3+xNTcbnhvCD+7mJ9s2Dav9YhzuXxUSR 0OKBcdX2hLoztRMsZkN1+r8tHXswEz9dkL4eehmPzfPNq6tERGlpN54IYrljLXmtkie1 jzgg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y72si1252290pfd.385.2017.10.06.06.35.15; Fri, 06 Oct 2017 06:35:15 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752634AbdJFNeu (ORCPT + 26 others); Fri, 6 Oct 2017 09:34:50 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:33580 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752312AbdJFNem (ORCPT ); Fri, 6 Oct 2017 09:34:42 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D203815A2; Fri, 6 Oct 2017 06:34:41 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A32453F5FD; Fri, 6 Oct 2017 06:34:41 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 4DA241AE028E; Fri, 6 Oct 2017 14:34:43 +0100 (BST) From: Will Deacon To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Jeremy.Linton@arm.com, peterz@infradead.org, mingo@redhat.com, longman@redhat.com, boqun.feng@gmail.com, paulmck@linux.vnet.ibm.com, Will Deacon Subject: [PATCH v2 1/5] kernel/locking: Use struct qrwlock instead of struct __qrwlock Date: Fri, 6 Oct 2017 14:34:38 +0100 Message-Id: <1507296882-18721-2-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1507296882-18721-1-git-send-email-will.deacon@arm.com> References: <1507296882-18721-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There's no good reason to keep the internal structure of struct qrwlock hidden from qrwlock.h, particularly as it's actually needed for unlock and ends up being abstracted independently behind the __qrwlock_write_byte function. Stop pretending we can hide this stuff, and move the __qrwlock definition into qrwlock, removing the __qrwlock_write_byte nastiness and using the same struct definition everywhere instead. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E. McKenney" Signed-off-by: Will Deacon --- include/asm-generic/qrwlock.h | 12 +----------- include/asm-generic/qrwlock_types.h | 15 +++++++++++++-- kernel/locking/qrwlock.c | 26 ++------------------------ 3 files changed, 16 insertions(+), 37 deletions(-) -- 2.1.4 diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 50925327b0a8..02c0a768e6b0 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -129,22 +129,12 @@ static inline void queued_read_unlock(struct qrwlock *lock) } /** - * __qrwlock_write_byte - retrieve the write byte address of a queue rwlock - * @lock : Pointer to queue rwlock structure - * Return: the write byte address of a queue rwlock - */ -static inline u8 *__qrwlock_write_byte(struct qrwlock *lock) -{ - return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN); -} - -/** * queued_write_unlock - release write lock of a queue rwlock * @lock : Pointer to queue rwlock structure */ static inline void queued_write_unlock(struct qrwlock *lock) { - smp_store_release(__qrwlock_write_byte(lock), 0); + smp_store_release(&lock->wmode, 0); } /* diff --git a/include/asm-generic/qrwlock_types.h b/include/asm-generic/qrwlock_types.h index 0abc6b6062fb..507f2dc51bba 100644 --- a/include/asm-generic/qrwlock_types.h +++ b/include/asm-generic/qrwlock_types.h @@ -9,12 +9,23 @@ */ typedef struct qrwlock { - atomic_t cnts; + union { + atomic_t cnts; + struct { +#ifdef __LITTLE_ENDIAN + u8 wmode; /* Writer mode */ + u8 rcnts[3]; /* Reader counts */ +#else + u8 rcnts[3]; /* Reader counts */ + u8 wmode; /* Writer mode */ +#endif + }; + }; arch_spinlock_t wait_lock; } arch_rwlock_t; #define __ARCH_RW_LOCK_UNLOCKED { \ - .cnts = ATOMIC_INIT(0), \ + { .cnts = ATOMIC_INIT(0), }, \ .wait_lock = __ARCH_SPIN_LOCK_UNLOCKED, \ } diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index 2655f26ec882..1af791e37348 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -23,26 +23,6 @@ #include #include -/* - * This internal data structure is used for optimizing access to some of - * the subfields within the atomic_t cnts. - */ -struct __qrwlock { - union { - atomic_t cnts; - struct { -#ifdef __LITTLE_ENDIAN - u8 wmode; /* Writer mode */ - u8 rcnts[3]; /* Reader counts */ -#else - u8 rcnts[3]; /* Reader counts */ - u8 wmode; /* Writer mode */ -#endif - }; - }; - arch_spinlock_t lock; -}; - /** * rspin_until_writer_unlock - inc reader count & spin until writer is gone * @lock : Pointer to queue rwlock structure @@ -125,10 +105,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock) * or wait for a previous writer to go away. */ for (;;) { - struct __qrwlock *l = (struct __qrwlock *)lock; - - if (!READ_ONCE(l->wmode) && - (cmpxchg_relaxed(&l->wmode, 0, _QW_WAITING) == 0)) + if (!READ_ONCE(lock->wmode) && + (cmpxchg_relaxed(&lock->wmode, 0, _QW_WAITING) == 0)) break; cpu_relax();