This is a note to let you know that I've just added the patch titled
tty/serial: at91: Handle shutdown more safely
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 0cc7c6c7916b1b6f34350ff1473b80b9f7e459c0 Mon Sep 17 00:00:00 2001
From: Marek Roszko <mark.roszko@xxxxxxxxx>
Date: Tue, 7 Jan 2014 11:45:06 +0100
Subject: tty/serial: at91: Handle shutdown more safely
Interrupts were being cleaned up late in the shutdown handler, it is possible
that an interrupt can occur and schedule a tasklet that runs after the port is
cleaned up. There is a null dereference due to this race condition with the
following stacktrace:
[<c02092b0>] (atmel_tasklet_func+0x514/0x814) from [<c001fd34>] (tasklet_action+0x70/0xa8)
[<c001fd34>] (tasklet_action+0x70/0xa8) from [<c001f60c>] (__do_softirq+0x90/0x144)
[<c001f60c>] (__do_softirq+0x90/0x144) from [<c001fa18>] (irq_exit+0x40/0x4c)
[<c001fa18>] (irq_exit+0x40/0x4c) from [<c000e298>] (handle_IRQ+0x64/0x84)
[<c000e298>] (handle_IRQ+0x64/0x84) from [<c000d6c0>] (__irq_svc+0x40/0x50)
[<c000d6c0>] (__irq_svc+0x40/0x50) from [<c0208060>] (atmel_rx_dma_release+0x88/0xb8)
[<c0208060>] (atmel_rx_dma_release+0x88/0xb8) from [<c0209740>] (atmel_shutdown+0x104/0x160)
[<c0209740>] (atmel_shutdown+0x104/0x160) from [<c0205e8c>] (uart_port_shutdown+0x2c/0x38)
Signed-off-by: Marek Roszko <mark.roszko@xxxxxxxxx>
Acked-by: Leilei Zhao <leilei.zhao@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.12
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index c7d99af46a96..48ea47a32d5f 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1650,12 +1650,24 @@ static int atmel_startup(struct uart_port *port)
static void atmel_shutdown(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
/*
- * Ensure everything is stopped.
+ * Clear out any scheduled tasklets before
+ * we destroy the buffers
+ */
+ tasklet_kill(&atmel_port->tasklet);
+
+ /*
+ * Ensure everything is stopped and
+ * disable all interrupts, port and break condition.
*/
atmel_stop_rx(port);
atmel_stop_tx(port);
+ UART_PUT_CR(port, ATMEL_US_RSTSTA);
+ UART_PUT_IDR(port, -1);
+
+
/*
* Shut-down the DMA.
*/
@@ -1665,12 +1677,6 @@ static void atmel_shutdown(struct uart_port *port)
atmel_port->release_tx(port);
/*
- * Disable all interrupts, port and break condition.
- */
- UART_PUT_CR(port, ATMEL_US_RSTSTA);
- UART_PUT_IDR(port, -1);
-
- /*
* Free the interrupt
*/
free_irq(port->irq, port);
--
1.8.5.1.163.gd7aced9
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