| Message ID | 492a48767eab5f7f7ffbe8a1dd1941a82f004e8b.1376923198.git.viresh.kumar@linaro.org |
|---|---|
| State | New |
| Headers | show
Return-Path: <patchwork-forward+bncBCRIZROPVQPBB366ZCIAKGQESQ5QN6Q@linaro.org> X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-ye0-f197.google.com (mail-ye0-f197.google.com [209.85.213.197]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 75574246F8 for <linaro@patches.linaro.org>; Mon, 19 Aug 2013 14:45:03 +0000 (UTC) Received: by mail-ye0-f197.google.com with SMTP id q8sf5198789yen.8 for <linaro@patches.linaro.org>; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:x-gm-message-state:delivered-to:from:to:cc:subject :date:message-id:in-reply-to:references:in-reply-to:references :x-original-sender:x-original-authentication-results:precedence :mailing-list:list-id:list-post:list-help:list-archive :list-unsubscribe; bh=Bly2QjZ36tfg5d+z7eMrMkHL9Y1sLSZ3Xg7sawVIao4=; b=mWdCBS/xWQ1+KP3FhUCquK6HQnwm/zZ6rOiV1/BAQ9Z3gP0NsXd9+KvbgpknNqrazP 9rpORhH4zyxQsVbMcnaSwwbILOD+cmUS/qCzVrHJTYMV+KFW7Ebyps0kaMi4yHabKoBr x1YmzmcsQTnFWlEmK7TazePiUWd8a3LYkfZRZ6iOzuYLMZrRfB4/vU7cZQFV/Q7cFe9W tkHBLvhaO9jifhiOL9KZfjSpYwzv34dgdrpgUIUpnl8e/aGEmxC6INDTyxOAOJ8Pb9pX aRoWNOu+l/X3lTiFgBpSEokX3/ocUdwHjPiTlMVD9IgppsYfwBMx0Wstz9Buckw0E907 UHIQ== X-Received: by 10.236.24.195 with SMTP id x43mr4287559yhx.3.1376923503273; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.99.10 with SMTP id em10ls1652614qeb.82.gmail; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) X-Received: by 10.58.75.41 with SMTP id z9mr13805586vev.4.1376923503169; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) Received: from mail-vb0-f41.google.com (mail-vb0-f41.google.com [209.85.212.41]) by mx.google.com with ESMTPS id x9si2433952vec.42.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:45:03 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.212.41 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.212.41; Received: by mail-vb0-f41.google.com with SMTP id g17so3290626vbg.14 for <patchwork-forward@linaro.org>; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) X-Gm-Message-State: ALoCoQlToSC82WEpovHlO2+c4zPXeCeC152cj+MNVgu/86V2SVeMTH+0cWkWvTrG22pz0MfkgqAM X-Received: by 10.220.47.10 with SMTP id l10mr407840vcf.32.1376923503078; Mon, 19 Aug 2013 07:45:03 -0700 (PDT) X-Forwarded-To: patchwork-forward@linaro.org X-Forwarded-For: patch@linaro.org patchwork-forward@linaro.org Delivered-To: patches@linaro.org Received: by 10.220.174.196 with SMTP id u4csp100096vcz; Mon, 19 Aug 2013 07:45:02 -0700 (PDT) X-Received: by 10.68.28.1 with SMTP id x1mr13503349pbg.113.1376923502150; Mon, 19 Aug 2013 07:45:02 -0700 (PDT) Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) by mx.google.com with ESMTPS id vs7si8629846pbc.235.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:45:02 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.192.174 is neither permitted nor denied by best guess record for domain of viresh.kumar@linaro.org) client-ip=209.85.192.174; Received: by mail-pd0-f174.google.com with SMTP id y13so5281796pdi.5 for <patches@linaro.org>; Mon, 19 Aug 2013 07:45:01 -0700 (PDT) X-Received: by 10.67.30.70 with SMTP id kc6mr7844386pad.32.1376923501636; Mon, 19 Aug 2013 07:45:01 -0700 (PDT) Received: from localhost ([122.172.193.46]) by mx.google.com with ESMTPSA id ut7sm15569634pbc.31.1969.12.31.16.00.00 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:45:00 -0700 (PDT) From: Viresh Kumar <viresh.kumar@linaro.org> To: gregkh@linuxfoundation.org, jslaby@suse.cz Cc: linaro-kernel@lists.linaro.org, patches@linaro.org, linux-serial@vger.kernel.org, Viresh Kumar <viresh.kumar@linaro.org> Subject: [PATCH V2 03/25] tty: serial: apbuart: drop uart_port->lock before calling tty_flip_buffer_push() Date: Mon, 19 Aug 2013 20:14:07 +0530 Message-Id: <492a48767eab5f7f7ffbe8a1dd1941a82f004e8b.1376923198.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 1.7.12.rc2.18.g61b472e In-Reply-To: <cover.1376923198.git.viresh.kumar@linaro.org> References: <cover.1376923198.git.viresh.kumar@linaro.org> In-Reply-To: <cover.1376923198.git.viresh.kumar@linaro.org> References: <cover.1376923198.git.viresh.kumar@linaro.org> X-Removed-Original-Auth: Dkim didn't pass. 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diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c index 6331464d..de11ab8 100644 --- a/drivers/tty/serial/apbuart.c +++ b/drivers/tty/serial/apbuart.c @@ -125,7 +125,9 @@ static void apbuart_rx_chars(struct uart_port *port) status = UART_GET_STATUS(port); } + spin_unlock(&port->lock); tty_flip_buffer_push(&port->state->port); + spin_lock(&port->lock); } static void apbuart_tx_chars(struct uart_port *port)
The current driver triggers a lockdep warning for if tty_flip_buffer_push() is called with uart_port->lock locked. This never shows up on UP kernels and comes up only on SMP kernels. Crash looks like this (produced with samsung.c driver): ----- [<c0014d58>] (unwind_backtrace+0x0/0xf8) from [<c0011908>] (show_stack+0x10/0x14) [<c0011908>] (show_stack+0x10/0x14) from [<c035da34>] (dump_stack+0x6c/0xac) [<c035da34>] (dump_stack+0x6c/0xac) from [<c01b59ac>] (do_raw_spin_unlock+0xc4/0xd8) [<c01b59ac>] (do_raw_spin_unlock+0xc4/0xd8) from [<c03627e4>] (_raw_spin_unlock_irqrestore+0xc/0) [<c03627e4>] (_raw_spin_unlock_irqrestore+0xc/0x38) from [<c020a1a8>] (s3c24xx_serial_rx_chars+0) [<c020a1a8>] (s3c24xx_serial_rx_chars+0x12c/0x260) from [<c020aae8>] (s3c64xx_serial_handle_irq+) [<c020aae8>] (s3c64xx_serial_handle_irq+0x48/0x60) from [<c006aaa0>] (handle_irq_event_percpu+0x) [<c006aaa0>] (handle_irq_event_percpu+0x50/0x194) from [<c006ac20>] (handle_irq_event+0x3c/0x5c) [<c006ac20>] (handle_irq_event+0x3c/0x5c) from [<c006d864>] (handle_fasteoi_irq+0x80/0x13c) [<c006d864>] (handle_fasteoi_irq+0x80/0x13c) from [<c006a4a4>] (generic_handle_irq+0x20/0x30) [<c006a4a4>] (generic_handle_irq+0x20/0x30) from [<c000f454>] (handle_IRQ+0x38/0x94) [<c000f454>] (handle_IRQ+0x38/0x94) from [<c0008538>] (gic_handle_irq+0x34/0x68) [<c0008538>] (gic_handle_irq+0x34/0x68) from [<c00123c0>] (__irq_svc+0x40/0x70) Exception stack(0xc04cdf70 to 0xc04cdfb8) df60: 00000000 00000000 0000166e 00000000 df80: c04cc000 c050278f c050278f 00000001 c04d444c 410fc0f4 c03649b0 00000000 dfa0: 00000001 c04cdfb8 c000f758 c000f75c 60070013 ffffffff [<c00123c0>] (__irq_svc+0x40/0x70) from [<c000f75c>] (arch_cpu_idle+0x28/0x30) [<c000f75c>] (arch_cpu_idle+0x28/0x30) from [<c0054888>] (cpu_startup_entry+0x5c/0x148) [<c0054888>] (cpu_startup_entry+0x5c/0x148) from [<c0497aa4>] (start_kernel+0x334/0x38c) BUG: spinlock lockup suspected on CPU#0, kworker/0:1/360 lock: s3c24xx_serial_ports+0x1d8/0x370, .magic: dead4ead, .owner: <none>/-1, .owner_cpu: -1 CPU: 0 PID: 360 Comm: kworker/0:1 Not tainted 3.11.0-rc6-next-20130819-00003-g75485f1 #2 Workqueue: events flush_to_ldisc [<c0014d58>] (unwind_backtrace+0x0/0xf8) from [<c0011908>] (show_stack+0x10/0x14) [<c0011908>] (show_stack+0x10/0x14) from [<c035da34>] (dump_stack+0x6c/0xac) [<c035da34>] (dump_stack+0x6c/0xac) from [<c01b581c>] (do_raw_spin_lock+0x100/0x17c) [<c01b581c>] (do_raw_spin_lock+0x100/0x17c) from [<c03628a0>] (_raw_spin_lock_irqsave+0x20/0x28) [<c03628a0>] (_raw_spin_lock_irqsave+0x20/0x28) from [<c0203224>] (uart_start+0x18/0x34) [<c0203224>] (uart_start+0x18/0x34) from [<c01ef890>] (__receive_buf+0x4b4/0x738) [<c01ef890>] (__receive_buf+0x4b4/0x738) from [<c01efb44>] (n_tty_receive_buf2+0x30/0x98) [<c01efb44>] (n_tty_receive_buf2+0x30/0x98) from [<c01f2ba8>] (flush_to_ldisc+0xec/0x138) [<c01f2ba8>] (flush_to_ldisc+0xec/0x138) from [<c0031af0>] (process_one_work+0xfc/0x348) [<c0031af0>] (process_one_work+0xfc/0x348) from [<c0032138>] (worker_thread+0x138/0x37c) [<c0032138>] (worker_thread+0x138/0x37c) from [<c0037a7c>] (kthread+0xa4/0xb0) [<c0037a7c>] (kthread+0xa4/0xb0) from [<c000e5f8>] (ret_from_fork+0x14/0x3c) ----- Release the port lock before calling tty_flip_buffer_push() and reacquire it after the call. Similar stuff was already done for few other drivers in the past, like: commit 2389b272168ceec056ca1d8a870a97fa9c26e11a Author: Thomas Gleixner <tglx@linutronix.de> Date: Tue May 29 21:53:50 2007 +0100 [ARM] 4417/1: Serial: Fix AMBA drivers locking Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/tty/serial/apbuart.c | 2 ++ 1 file changed, 2 insertions(+)