From patchwork Tue Sep 1 15:10:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 310491 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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 E83E3C433E7 for ; Tue, 1 Sep 2020 15:34:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B958520E65 for ; Tue, 1 Sep 2020 15:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974495; bh=jYb4GQxI7atbxo7wKSsAyMnuCDwEneApn0EWTOBjdjk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bMuETPOl7qq7urxFqu68ojd5kZVhQxqg9AWky0y/0ILpx7UpopogX/Pu6YCsVWKcS 6eYsH3NV4nF1tLfhO2UD8yKFUb96LcSdEjYQ/bWnB/DlfN5eqPl13oAFoG2Cmky8gJ w5h0eQ00yP/Etb+kVBrR6Pbohj4xd2ugJtW+OR/A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727956AbgIAPex (ORCPT ); Tue, 1 Sep 2020 11:34:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:40086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730069AbgIAPev (ORCPT ); Tue, 1 Sep 2020 11:34:51 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1E16A20866; Tue, 1 Sep 2020 15:34:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974490; bh=jYb4GQxI7atbxo7wKSsAyMnuCDwEneApn0EWTOBjdjk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M+tEJ1QcGsSd5v67yH97HS1QfMbQ1cLwjl59xtGz0W/CT/HMqD8maugDyJtwfOA7+ grc7rKuViuZDL330pxEADFay0tJ8NTTC1BVJvt+9CYc4CToNUpmMD9CVl2qsRDntKG DGl/0U4sa/kq6tE61ivK6VDHW/1poJK3K7HcaKIE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Senozhatsky , Guenter Roeck , Raul Rangel , Andy Shevchenko Subject: [PATCH 5.4 166/214] serial: 8250: change lock order in serial8250_do_startup() Date: Tue, 1 Sep 2020 17:10:46 +0200 Message-Id: <20200901151000.930281293@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150952.963606936@linuxfoundation.org> References: <20200901150952.963606936@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sergey Senozhatsky commit 205d300aea75623e1ae4aa43e0d265ab9cf195fd upstream. We have a number of "uart.port->desc.lock vs desc.lock->uart.port" lockdep reports coming from 8250 driver; this causes a bit of trouble to people, so let's fix it. The problem is reverse lock order in two different call paths: chain #1: serial8250_do_startup() spin_lock_irqsave(&port->lock); disable_irq_nosync(port->irq); raw_spin_lock_irqsave(&desc->lock) chain #2: __report_bad_irq() raw_spin_lock_irqsave(&desc->lock) for_each_action_of_desc() printk() spin_lock_irqsave(&port->lock); Fix this by changing the order of locks in serial8250_do_startup(): do disable_irq_nosync() first, which grabs desc->lock, and grab uart->port after that, so that chain #1 and chain #2 have same lock order. Full lockdep splat: ====================================================== WARNING: possible circular locking dependency detected 5.4.39 #55 Not tainted ====================================================== swapper/0/0 is trying to acquire lock: ffffffffab65b6c0 (console_owner){-...}, at: console_lock_spinning_enable+0x31/0x57 but task is already holding lock: ffff88810a8e34c0 (&irq_desc_lock_class){-.-.}, at: __report_bad_irq+0x5b/0xba which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&irq_desc_lock_class){-.-.}: _raw_spin_lock_irqsave+0x61/0x8d __irq_get_desc_lock+0x65/0x89 __disable_irq_nosync+0x3b/0x93 serial8250_do_startup+0x451/0x75c uart_startup+0x1b4/0x2ff uart_port_activate+0x73/0xa0 tty_port_open+0xae/0x10a uart_open+0x1b/0x26 tty_open+0x24d/0x3a0 chrdev_open+0xd5/0x1cc do_dentry_open+0x299/0x3c8 path_openat+0x434/0x1100 do_filp_open+0x9b/0x10a do_sys_open+0x15f/0x3d7 kernel_init_freeable+0x157/0x1dd kernel_init+0xe/0x105 ret_from_fork+0x27/0x50 -> #1 (&port_lock_key){-.-.}: _raw_spin_lock_irqsave+0x61/0x8d serial8250_console_write+0xa7/0x2a0 console_unlock+0x3b7/0x528 vprintk_emit+0x111/0x17f printk+0x59/0x73 register_console+0x336/0x3a4 uart_add_one_port+0x51b/0x5be serial8250_register_8250_port+0x454/0x55e dw8250_probe+0x4dc/0x5b9 platform_drv_probe+0x67/0x8b really_probe+0x14a/0x422 driver_probe_device+0x66/0x130 device_driver_attach+0x42/0x5b __driver_attach+0xca/0x139 bus_for_each_dev+0x97/0xc9 bus_add_driver+0x12b/0x228 driver_register+0x64/0xed do_one_initcall+0x20c/0x4a6 do_initcall_level+0xb5/0xc5 do_basic_setup+0x4c/0x58 kernel_init_freeable+0x13f/0x1dd kernel_init+0xe/0x105 ret_from_fork+0x27/0x50 -> #0 (console_owner){-...}: __lock_acquire+0x118d/0x2714 lock_acquire+0x203/0x258 console_lock_spinning_enable+0x51/0x57 console_unlock+0x25d/0x528 vprintk_emit+0x111/0x17f printk+0x59/0x73 __report_bad_irq+0xa3/0xba note_interrupt+0x19a/0x1d6 handle_irq_event_percpu+0x57/0x79 handle_irq_event+0x36/0x55 handle_fasteoi_irq+0xc2/0x18a do_IRQ+0xb3/0x157 ret_from_intr+0x0/0x1d cpuidle_enter_state+0x12f/0x1fd cpuidle_enter+0x2e/0x3d do_idle+0x1ce/0x2ce cpu_startup_entry+0x1d/0x1f start_kernel+0x406/0x46a secondary_startup_64+0xa4/0xb0 other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &irq_desc_lock_class Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&irq_desc_lock_class); lock(&port_lock_key); lock(&irq_desc_lock_class); lock(console_owner); *** DEADLOCK *** 2 locks held by swapper/0/0: #0: ffff88810a8e34c0 (&irq_desc_lock_class){-.-.}, at: __report_bad_irq+0x5b/0xba #1: ffffffffab65b5c0 (console_lock){+.+.}, at: console_trylock_spinning+0x20/0x181 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.39 #55 Hardware name: XXXXXX Call Trace: dump_stack+0xbf/0x133 ? print_circular_bug+0xd6/0xe9 check_noncircular+0x1b9/0x1c3 __lock_acquire+0x118d/0x2714 lock_acquire+0x203/0x258 ? console_lock_spinning_enable+0x31/0x57 console_lock_spinning_enable+0x51/0x57 ? console_lock_spinning_enable+0x31/0x57 console_unlock+0x25d/0x528 ? console_trylock+0x18/0x4e vprintk_emit+0x111/0x17f ? lock_acquire+0x203/0x258 printk+0x59/0x73 __report_bad_irq+0xa3/0xba note_interrupt+0x19a/0x1d6 handle_irq_event_percpu+0x57/0x79 handle_irq_event+0x36/0x55 handle_fasteoi_irq+0xc2/0x18a do_IRQ+0xb3/0x157 common_interrupt+0xf/0xf Signed-off-by: Sergey Senozhatsky Fixes: 768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and RT kernels") Reported-by: Guenter Roeck Reported-by: Raul Rangel BugLink: https://bugs.chromium.org/p/chromium/issues/detail?id=1114800 Link: https://lore.kernel.org/lkml/CAHQZ30BnfX+gxjPm1DUd5psOTqbyDh4EJE=2=VAMW_VDafctkA@mail.gmail.com/T/#u Reviewed-by: Andy Shevchenko Reviewed-by: Guenter Roeck Tested-by: Guenter Roeck Cc: stable Link: https://lore.kernel.org/r/20200817022646.1484638-1-sergey.senozhatsky@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2198,6 +2198,10 @@ int serial8250_do_startup(struct uart_po if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { unsigned char iir1; + + if (port->irqflags & IRQF_SHARED) + disable_irq_nosync(port->irq); + /* * Test for UARTs that do not reassert THRE when the * transmitter is idle and the interrupt has already @@ -2207,8 +2211,6 @@ int serial8250_do_startup(struct uart_po * allow register changes to become visible. */ spin_lock_irqsave(&port->lock, flags); - if (up->port.irqflags & IRQF_SHARED) - disable_irq_nosync(port->irq); wait_for_xmitr(up, UART_LSR_THRE); serial_port_out_sync(port, UART_IER, UART_IER_THRI); @@ -2220,9 +2222,10 @@ int serial8250_do_startup(struct uart_po iir = serial_port_in(port, UART_IIR); serial_port_out(port, UART_IER, 0); + spin_unlock_irqrestore(&port->lock, flags); + if (port->irqflags & IRQF_SHARED) enable_irq(port->irq); - spin_unlock_irqrestore(&port->lock, flags); /* * If the interrupt is not reasserted, or we otherwise