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] [<c002a790>] (unwind_backtrace+0x0/0xf0) from
[<c012f8f0>] (do_raw_spin_lock+0x10c/0x148)
[ 68.050000] [<c012f8f0>] (do_raw_spin_lock+0x10c/0x148) from
[<c015152c>] (atmel_tasklet_func+0x10/0x708)
[ 68.060000] [<c015152c>] (atmel_tasklet_func+0x10/0x708) from
[<c003bfd4>] (tasklet_action+0x8c/0xf4)
[ 68.070000] [<c003bfd4>] (tasklet_action+0x8c/0xf4) from [<c003c630>]
(__do_softirq+0xa4/0x180)
[ 68.080000] [<c003c630>] (__do_softirq+0xa4/0x180) from [<c003c764>]
(irq_exit+0x58/0xb0)
[ 68.090000] [<c003c764>] (irq_exit+0x58/0xb0) from [<c0021084>]
(asm_do_IRQ+0x84/0xa4)
[ 68.100000] [<c0021084>] (asm_do_IRQ+0x84/0xa4) from [<c002622c>]
(__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] [<c002622c>] (__irq_svc+0x4c/0x98) from [<c023d9c0>]
(_raw_spin_unlock+0x0/0x48)
[ 68.140000] [<c023d9c0>] (_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): [<c0035e30>]
copy_process+0x308/0xe78
[ 126.750000] softirqs last enabled at (0): [<c0035e30>]
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<claudio@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Bender<codehero@xxxxxxxxx>
Tested-by: Dave Bender<codehero@xxxxxxxxx>
Acked-by: Nicolas Ferre<nicolas.ferre@xxxxxxxxx>
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<stable@xxxxxxxxxx>
That address has been invalid since August, please use
stable@xxxxxxxxxxxxxxx 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 <claudio@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Bender <codehero@xxxxxxxxx>
Tested-by: Dave Bender <codehero@xxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
---
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
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