From patchwork Mon Aug 19 14:44:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viresh Kumar X-Patchwork-Id: 19314 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-ve0-f197.google.com (mail-ve0-f197.google.com [209.85.128.197]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id B7FDD246F8 for ; Mon, 19 Aug 2013 14:46:42 +0000 (UTC) Received: by mail-ve0-f197.google.com with SMTP id ox1sf5609414veb.8 for ; Mon, 19 Aug 2013 07:46:42 -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=Ijegm2LLKwEThiJBs0NkkgVdbeyO4yNnEivnwtPV8XM=; b=ILuZNZlEYOh7Vi3H2LQDgQC2+P0V8uJt2cV3DV3lW9hCj+TFDasNhrvkz2zP1ALYma ZFspXgZqoGI+QkPony0W+x0nmJOnDnKS3TvdVjeugu2Kn/Gt4uS6TKdx0/cxQuezikHS 9XLzyA3tQoZB+r7a5zyReMoaMdebcXHfu22l1GA5O0kzeI9p7PEiQn2TbjI6psFsbS18 MjANFBD9qG0BRHJMcE1vxrq69A0fI/r42mrksjmW++YDCJO/6XGeQqt966bdgen8Uv6V hDkSDeqUkur6ijOBbDG7yvDd4s6GUCwfY7DYLv04EPuRfkMGBef/RKsrF8LHSvrfIp6C X42g== X-Received: by 10.236.166.35 with SMTP id f23mr4361241yhl.22.1376923602442; Mon, 19 Aug 2013 07:46:42 -0700 (PDT) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.48.49 with SMTP id i17ls1787100qen.44.gmail; Mon, 19 Aug 2013 07:46:42 -0700 (PDT) X-Received: by 10.52.73.162 with SMTP id m2mr2932075vdv.24.1376923602301; Mon, 19 Aug 2013 07:46:42 -0700 (PDT) Received: from mail-ve0-f177.google.com (mail-ve0-f177.google.com [209.85.128.177]) by mx.google.com with ESMTPS id x16si2436780vcu.25.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:42 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.128.177 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.128.177; Received: by mail-ve0-f177.google.com with SMTP id cz11so2978343veb.22 for ; Mon, 19 Aug 2013 07:46:42 -0700 (PDT) X-Gm-Message-State: ALoCoQk75RsdtLCjde4/I3q/qLk9Amj+RQDmOovoYW1ttjLKsC9fLXXI29feQtAtbLIPjzZx2KcJ X-Received: by 10.220.174.200 with SMTP id u8mr13838368vcz.6.1376923602215; Mon, 19 Aug 2013 07:46:42 -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 u4csp100194vcz; Mon, 19 Aug 2013 07:46:41 -0700 (PDT) X-Received: by 10.66.230.233 with SMTP id tb9mr13919049pac.38.1376923601321; Mon, 19 Aug 2013 07:46:41 -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 tp5si8783872pac.338.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:41 -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 y13so5283987pdi.5 for ; Mon, 19 Aug 2013 07:46:40 -0700 (PDT) X-Received: by 10.66.163.199 with SMTP id yk7mr3416339pab.136.1376923600768; Mon, 19 Aug 2013 07:46:40 -0700 (PDT) Received: from localhost ([122.172.193.46]) by mx.google.com with ESMTPSA id pq1sm15581602pbb.26.1969.12.31.16.00.00 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 19 Aug 2013 07:46:40 -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 17/25] tty: serial: netx: drop uart_port->lock before calling tty_flip_buffer_push() Date: Mon, 19 Aug 2013 20:14:21 +0530 Message-Id: <11935d0be9aba5b33d05f1f779eb7dbf61bf2f8c.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: 209.85.128.177 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/netx-serial.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/netx-serial.c b/drivers/tty/serial/netx-serial.c index ce04f3f..0a4dd70 100644 --- a/drivers/tty/serial/netx-serial.c +++ b/drivers/tty/serial/netx-serial.c @@ -196,7 +196,7 @@ static void netx_txint(struct uart_port *port) uart_write_wakeup(port); } -static void netx_rxint(struct uart_port *port) +static void netx_rxint(struct uart_port *port, unsigned long *flags) { unsigned char rx, flg, status; @@ -236,7 +236,9 @@ static void netx_rxint(struct uart_port *port) uart_insert_char(port, status, SR_OE, rx, flg); } + spin_unlock_irqrestore(&port->lock, *flags); tty_flip_buffer_push(&port->state->port); + spin_lock_irqsave(&port->lock, *flags); } static irqreturn_t netx_int(int irq, void *dev_id) @@ -250,7 +252,7 @@ static irqreturn_t netx_int(int irq, void *dev_id) status = readl(port->membase + UART_IIR) & IIR_MASK; while (status) { if (status & IIR_RIS) - netx_rxint(port); + netx_rxint(port, &flags); if (status & IIR_TIS) netx_txint(port); if (status & IIR_MIS) {