[PATCH 3/4] tty/serial: at91: prevent null dereference in tasklet function

From: Nicolas Ferre
Date: Tue Jan 07 2014 - 05:46:29 EST

From: Marek Roszko <mark.roszko@xxxxxxxxx>

Something asks a tasklet to be scheduled when the uart port is closed.
Need to supress the kernel panic for now by checking if the port is NULL or

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>
drivers/tty/serial/atmel_serial.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index c421d11b3d4c..6e68486c83cb 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1360,6 +1360,10 @@ static void atmel_tasklet_func(unsigned long data)
unsigned int status;
unsigned int status_change;

+ if(!port->state || !port->state->port.tty)
+ /* uart has been closed */
+ return;
/* The interrupt handler does not take the lock */


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