From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759731Ab1LPOQ3 (ORCPT ); Fri, 16 Dec 2011 09:16:29 -0500 Received: from bishop.asidev.net ([95.141.38.214]:43945 "EHLO bishop.asidev.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751966Ab1LPOQX (ORCPT ); Fri, 16 Dec 2011 09:16:23 -0500 Message-ID: <4EEB50F1.3040106@evidence.eu.com> Date: Fri, 16 Dec 2011 15:08:49 +0100 From: Claudio Scordino User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.23) Gecko/20110922 Lightning/1.0b2 Thunderbird/3.1.15 MIME-Version: 1.0 To: Greg KH CC: Alan Cox , Nicolas Ferre , Linux Kernel , "linux-serial@vger.kernel.org" , Dave Bender , stable@vger.kernel.org Subject: Re: [PATCH] atmel_serial: fix spinlock lockup in RS485 code References: <4EE9B42F.50004@evidence.eu.com> <4EE9C532.5050607@atmel.com> <4EE9D44A.6010300@evidence.eu.com> <20111215185814.GD18791@kroah.com> In-Reply-To: <20111215185814.GD18791@kroah.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 15/12/2011 19:58, Greg KH ha scritto: > On Thu, Dec 15, 2011 at 12:04:42PM +0100, Claudio Scordino wrote: >> Il 15/12/2011 11:00, Nicolas Ferre ha scritto: >>> On 12/15/2011 09:47 AM, Claudio Scordino : >>>> Hi all. >>>> >>>> We have encountered a spinlock lockup in the RS485 part of the >>>> atmel_serial driver. >>>> >>>> Here is the trace: >>>> >>>> [ 68.030000] BUG: spinlock lockup on CPU#0, dnp_master/244, c07e82c0 >>>> [ 68.040000] [] (unwind_backtrace+0x0/0xf0) from >>>> [] (do_raw_spin_lock+0x10c/0x148) >>>> [ 68.050000] [] (do_raw_spin_lock+0x10c/0x148) from >>>> [] (atmel_tasklet_func+0x10/0x708) >>>> [ 68.060000] [] (atmel_tasklet_func+0x10/0x708) from >>>> [] (tasklet_action+0x8c/0xf4) >>>> [ 68.070000] [] (tasklet_action+0x8c/0xf4) from [] >>>> (__do_softirq+0xa4/0x180) >>>> [ 68.080000] [] (__do_softirq+0xa4/0x180) from [] >>>> (irq_exit+0x58/0xb0) >>>> [ 68.090000] [] (irq_exit+0x58/0xb0) from [] >>>> (asm_do_IRQ+0x84/0xa4) >>>> [ 68.100000] [] (asm_do_IRQ+0x84/0xa4) from [] >>>> (__irq_svc+0x4c/0x98) >>>> [ 68.110000] Exception stack(0xc341fdc8 to 0xc341fe10) >>>> [ 68.110000] fdc0: c07e82c0 00000000 00000200 >>>> c4818000 c341fe10 c07e82c0 >>>> [ 68.120000] fde0: 00000000 c07e82c0 c38d3318 c341e000 bebcee00 >>>> 010a0b60 c07e83fc c341fe10 >>>> [ 68.130000] fe00: c0151d54 c023d9c0 60000013 ffffffff >>>> [ 68.140000] [] (__irq_svc+0x4c/0x98) from [] >>>> (_raw_spin_unlock+0x0/0x48) >>>> [ 68.140000] [] (_raw_spin_unlock+0x0/0x48) from >>>> [<00000000>] ( (null)) >>>> >>>> The soft lockup occurs later >>>> >>>> [ 126.750000] BUG: soft lockup - CPU#0 stuck for 61s! [dnp_master:244] >>>> [ 126.750000] irq event stamp: 0 >>>> [ 126.750000] hardirqs last enabled at (0): [< (null)>] (null) >>>> [ 126.750000] hardirqs last disabled at (0): [] >>>> copy_process+0x308/0xe78 >>>> [ 126.750000] softirqs last enabled at (0): [] >>>> copy_process+0x308/0xe78 >>>> [ 126.750000] softirqs last disabled at (0): [< (null)>] (null) >>>> >>>> >>>> The following patch (already tested by Dave, who also reported the bug) >>>> fixes the problem. >>>> >>>> Regards, >>>> >>>> Claudio >>>> >>>> >>>> >>>> >>>> Subject: atmel_serial: fix spinlock lockup in RS485 code >>>> >>>> Patch to fix a spinlock lockup in the driver that sometimes happens when >>>> the >>>> tasklet starts. >>>> >>>> Signed-off-by: Claudio Scordino >>>> Signed-off-by: Dave Bender >>>> Tested-by: Dave Bender >>> >>> Acked-by: Nicolas Ferre >>> >>> Claudio, can you please send the patch to Alan with my "Acked-by" and an >>> addition to Linux stable just after the signature lines: >>> >>> Cc: stable > > That address has been invalid since August, please use > stable@vger.kernel.org now. Hi Greg, here is the patch with the right address. Many thanks for taking care of it. Best regards, Claudio Subject: atmel_serial: fix spinlock lockup in RS485 code Patch to fix a spinlock lockup in the driver that sometimes happens when the tasklet starts. Signed-off-by: Claudio Scordino Signed-off-by: Dave Bender Tested-by: Dave Bender Acked-by: Nicolas Ferre Acked-by: Alan Cox Cc: stable --- drivers/tty/serial/atmel_serial.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 4c823f3..90c8e3a 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -212,8 +212,9 @@ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); unsigned int mode; + unsigned long flags; - spin_lock(&port->lock); + spin_lock_irqsave(&port->lock, flags); /* Disable interrupts */ UART_PUT_IDR(port, atmel_port->tx_done_mask); @@ -244,7 +245,7 @@ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) /* Enable interrupts */ UART_PUT_IER(port, atmel_port->tx_done_mask); - spin_unlock(&port->lock); + spin_unlock_irqrestore(&port->lock, flags); } -- 1.7.1