From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH V2 00/25] tty: serial: drop uart_port->lock before calling Date: Mon, 19 Aug 2013 11:31:16 -0400 Message-ID: <52123A44.9090608@hurleysoftware.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout39.mail01.mtsvc.net ([216.70.64.83]:58835 "EHLO n12.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750793Ab3HSPbY (ORCPT ); Mon, 19 Aug 2013 11:31:24 -0400 In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Viresh Kumar Cc: gregkh@linuxfoundation.org, jslaby@suse.cz, linaro-kernel@lists.linaro.org, patches@linaro.org, linux-serial@vger.kernel.org, Bryan Huntsman , Daniel Walker , David Brown , Stephen Warren , Tobias Klauser , Tony Prisk On 08/19/2013 10:44 AM, Viresh Kumar wrote: > Many serial 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): Please review commit 677fe555cbfb188af58cce105f4dae9505e58c31 'serial: imx: Fix recursive locking bug' to see if that is actually the problem you're having with the samsung serial 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) > ----- > > This patchset modifies these drivers to 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 > > This is build tested for all drivers and tested on Samsung's Arndale board for > samsung.c driver. Rebased over linux-next (Problem was reproduced on this > branch): > > commit 1e712b0818569846d6b926ecb6bf32b3dea73609 > Author: Stephen Rothwell > Date: Fri Aug 16 17:06:26 2013 +1000 > > Add linux-next specific files for 20130816 > > Signed-off-by: Stephen Rothwell > > Cc: Bryan Huntsman > Cc: Daniel Walker > Cc: David Brown > Cc: Stephen Warren > Cc: Tobias Klauser > Cc: Tony Prisk > > Viresh Kumar (25): > tty: serial: altera_jtag: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: altera: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: apbuart: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: ar933x: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: arc: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: bcm63xx: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: bfin_sport: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: efm32: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: icom: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: lpc32xx_hs: don't call tty_flip_buffer_push() twice > tty: serial: lpc32xx_hs: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: m32r_sio: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: mcf: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: mfd: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: mpsc: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: msm: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: netx: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: nwpserial: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: pnx8xxx: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: rp2: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: sa1100: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: samsung: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: tegra: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: sirfsoc: drop uart_port->lock before calling > tty_flip_buffer_push() > tty: serial: vt8500: drop uart_port->lock before calling > tty_flip_buffer_push() > > drivers/tty/serial/altera_jtaguart.c | 2 ++ > drivers/tty/serial/altera_uart.c | 2 ++ > drivers/tty/serial/apbuart.c | 2 ++ > drivers/tty/serial/ar933x_uart.c | 2 ++ > drivers/tty/serial/arc_uart.c | 2 ++ > drivers/tty/serial/bcm63xx_uart.c | 2 ++ > drivers/tty/serial/bfin_sport_uart.c | 5 +++-- > drivers/tty/serial/efm32-uart.c | 4 ++-- > drivers/tty/serial/icom.c | 3 +++ > drivers/tty/serial/lpc32xx_hs.c | 7 ++++--- > drivers/tty/serial/m32r_sio.c | 3 +++ > drivers/tty/serial/mcf.c | 2 ++ > drivers/tty/serial/mfd.c | 14 ++++++++++---- > drivers/tty/serial/mpsc.c | 11 ++++++++--- > drivers/tty/serial/msm_serial.c | 5 +++++ > drivers/tty/serial/netx-serial.c | 6 ++++-- > drivers/tty/serial/nwpserial.c | 3 +++ > drivers/tty/serial/pnx8xxx_uart.c | 3 +++ > drivers/tty/serial/rp2.c | 2 ++ > drivers/tty/serial/sa1100.c | 3 +++ > drivers/tty/serial/samsung.c | 5 ++++- > drivers/tty/serial/serial-tegra.c | 10 ++++++++-- > drivers/tty/serial/sirfsoc_uart.c | 3 +++ > drivers/tty/serial/vt8500_serial.c | 2 ++ > 24 files changed, 84 insertions(+), 19 deletions(-) >