[PATCH 3.12 056/133] tty/serial: at91: fix race condition in atmel_serial_remove

From: Greg Kroah-Hartman
Date: Tue Feb 04 2014 - 17:17:44 EST

3.12-stable review patch. If anyone has any objections, please let me know.


From: Marek Roszko <mark.roszko@xxxxxxxxx>

commit f50c995f9ebf064cea1368bf361c4e29679415b4 upstream.

The _remove callback could be called when a tasklet is scheduled. tasklet_kill
was called inside the function in order to free up any scheduled tasklets.
However it was called after uart_remove_one_port which destroys tty references
needed in the port for atmel_tasklet_func.
Simply putting the tasklet_kill at the start of the function will prevent this

Signed-off-by: Marek Roszko <mark.roszko@xxxxxxxxx>
Acked-by: Leilei Zhao <leilei.zhao@xxxxxxxxx>
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/tty/serial/atmel_serial.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2430,11 +2430,12 @@ static int atmel_serial_remove(struct pl
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
int ret = 0;

+ tasklet_kill(&atmel_port->tasklet);
device_init_wakeup(&pdev->dev, 0);

ret = uart_remove_one_port(&atmel_uart, port);

- tasklet_kill(&atmel_port->tasklet);

/* "port" is allocated statically, so we shouldn't free it */

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