From patchwork Mon Aug 19 14:44:23 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viresh Kumar X-Patchwork-Id: 19316 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-gh0-f200.google.com (mail-gh0-f200.google.com [209.85.160.200]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 40AF4246F8 for ; Mon, 19 Aug 2013 14:46:57 +0000 (UTC) Received: by mail-gh0-f200.google.com with SMTP id 10sf3898215ghy.3 for ; Mon, 19 Aug 2013 07:46:57 -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=7mTDIY/HVBelVjxhzMTg8KpQKoNBBAXAGY1314yyhJw=; b=MJnZqkVue8trEwqRYw3r31Qq87g9JSVXafiaB4+0dql/KPY0t16RPxgpG8dA/WBVDZ dsAuyOTzJVlpDSKvJUZSJEVX9m+1eUN6pXekkrJKuvba4vbuSKUWmgH73kjyuqwcVOE/ rndyGpuYaUtDvvFPB6Jd2a7eUh7O749ktqSJ3KTRzZT40X4WR4f+wPCzKPjSe4avfE7G JxfADUC+4mAACOxiq2bRvPIRDloMcqs8smNXDI5/zgJc1HukM8VsmKnhW37bOy2uMW8u qUqeiNr/YeWiLjOL7k46gfL4nPbsedwtNW42gi/ic06FB/n7/oeUW3F//R8qwRkthyIT XRAA== X-Received: by 10.236.103.134 with SMTP id f6mr4013184yhg.37.1376923617002; Mon, 19 Aug 2013 07:46:57 -0700 (PDT) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.118.136 with SMTP id km8ls1803353qeb.32.gmail; Mon, 19 Aug 2013 07:46:56 -0700 (PDT) X-Received: by 10.52.165.45 with SMTP id yv13mr11703659vdb.1.1376923616666; Mon, 19 Aug 2013 07:46:56 -0700 (PDT) Received: from mail-vb0-f44.google.com (mail-vb0-f44.google.com [209.85.212.44]) by mx.google.com with ESMTPS id sk7si2073298vdc.12.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:56 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.212.44 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.212.44; Received: by mail-vb0-f44.google.com with SMTP id e13so3345784vbg.3 for ; Mon, 19 Aug 2013 07:46:56 -0700 (PDT) X-Gm-Message-State: ALoCoQmGT/md6OmBOiLSqmkCCAoXJozz/jfioj66uVusJAmqAEbsuMSrVQ1DFuBeXCaDVa32/luj X-Received: by 10.221.64.17 with SMTP id xg17mr13718674vcb.5.1376923616572; Mon, 19 Aug 2013 07:46:56 -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 u4csp100207vcz; Mon, 19 Aug 2013 07:46:56 -0700 (PDT) X-Received: by 10.66.162.136 with SMTP id ya8mr13615156pab.110.1376923615670; Mon, 19 Aug 2013 07:46:55 -0700 (PDT) Received: from mail-pd0-f177.google.com (mail-pd0-f177.google.com [209.85.192.177]) by mx.google.com with ESMTPS id zo4si8623046pbc.282.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:55 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.192.177 is neither permitted nor denied by best guess record for domain of viresh.kumar@linaro.org) client-ip=209.85.192.177; Received: by mail-pd0-f177.google.com with SMTP id y10so5256319pdj.8 for ; Mon, 19 Aug 2013 07:46:55 -0700 (PDT) X-Received: by 10.66.178.143 with SMTP id cy15mr13919120pac.105.1376923615255; Mon, 19 Aug 2013 07:46:55 -0700 (PDT) Received: from localhost ([122.172.193.46]) by mx.google.com with ESMTPSA id om2sm15572641pbc.30.1969.12.31.16.00.00 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:54 -0700 (PDT) From: Viresh Kumar To: gregkh@linuxfoundation.org, jslaby@suse.cz Cc: linaro-kernel@lists.linaro.org, patches@linaro.org, linux-serial@vger.kernel.org, Viresh Kumar Subject: [PATCH V2 19/25] tty: serial: pnx8xxx: drop uart_port->lock before calling tty_flip_buffer_push() Date: Mon, 19 Aug 2013 20:14:23 +0530 Message-Id: <3cba84201b21685bfa998e771fb68c2aed864dc2.1376923198.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 1.7.12.rc2.18.g61b472e In-Reply-To: References: In-Reply-To: References: X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: viresh.kumar@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.212.44 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , 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): ----- [] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14) [] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac) [] (dump_stack+0x6c/0xac) from [] (do_raw_spin_unlock+0xc4/0xd8) [] (do_raw_spin_unlock+0xc4/0xd8) from [] (_raw_spin_unlock_irqrestore+0xc/0) [] (_raw_spin_unlock_irqrestore+0xc/0x38) from [] (s3c24xx_serial_rx_chars+0) [] (s3c24xx_serial_rx_chars+0x12c/0x260) from [] (s3c64xx_serial_handle_irq+) [] (s3c64xx_serial_handle_irq+0x48/0x60) from [] (handle_irq_event_percpu+0x) [] (handle_irq_event_percpu+0x50/0x194) from [] (handle_irq_event+0x3c/0x5c) [] (handle_irq_event+0x3c/0x5c) from [] (handle_fasteoi_irq+0x80/0x13c) [] (handle_fasteoi_irq+0x80/0x13c) from [] (generic_handle_irq+0x20/0x30) [] (generic_handle_irq+0x20/0x30) from [] (handle_IRQ+0x38/0x94) [] (handle_IRQ+0x38/0x94) from [] (gic_handle_irq+0x34/0x68) [] (gic_handle_irq+0x34/0x68) from [] (__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 [] (__irq_svc+0x40/0x70) from [] (arch_cpu_idle+0x28/0x30) [] (arch_cpu_idle+0x28/0x30) from [] (cpu_startup_entry+0x5c/0x148) [] (cpu_startup_entry+0x5c/0x148) from [] (start_kernel+0x334/0x38c) BUG: spinlock lockup suspected on CPU#0, kworker/0:1/360 lock: s3c24xx_serial_ports+0x1d8/0x370, .magic: dead4ead, .owner: /-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 [] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14) [] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac) [] (dump_stack+0x6c/0xac) from [] (do_raw_spin_lock+0x100/0x17c) [] (do_raw_spin_lock+0x100/0x17c) from [] (_raw_spin_lock_irqsave+0x20/0x28) [] (_raw_spin_lock_irqsave+0x20/0x28) from [] (uart_start+0x18/0x34) [] (uart_start+0x18/0x34) from [] (__receive_buf+0x4b4/0x738) [] (__receive_buf+0x4b4/0x738) from [] (n_tty_receive_buf2+0x30/0x98) [] (n_tty_receive_buf2+0x30/0x98) from [] (flush_to_ldisc+0xec/0x138) [] (flush_to_ldisc+0xec/0x138) from [] (process_one_work+0xfc/0x348) [] (process_one_work+0xfc/0x348) from [] (worker_thread+0x138/0x37c) [] (worker_thread+0x138/0x37c) from [] (kthread+0xa4/0xb0) [] (kthread+0xa4/0xb0) from [] (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 Date: Tue May 29 21:53:50 2007 +0100 [ARM] 4417/1: Serial: Fix AMBA drivers locking Signed-off-by: Viresh Kumar --- drivers/tty/serial/pnx8xxx_uart.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/pnx8xxx_uart.c b/drivers/tty/serial/pnx8xxx_uart.c index b6b7aca..de6c05c 100644 --- a/drivers/tty/serial/pnx8xxx_uart.c +++ b/drivers/tty/serial/pnx8xxx_uart.c @@ -237,7 +237,10 @@ static void pnx8xxx_rx_chars(struct pnx8xxx_port *sport) status = FIFO_TO_SM(serial_in(sport, PNX8XXX_FIFO)) | ISTAT_TO_SM(serial_in(sport, PNX8XXX_ISTAT)); } + + spin_unlock(&sport->port.lock); tty_flip_buffer_push(&sport->port.state->port); + spin_lock(&sport->port.lock); } static void pnx8xxx_tx_chars(struct pnx8xxx_port *sport)