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

[Greg Kroah-Hartman]

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
conflict.

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);
 	kfree(atmel_port->rx_ring.buf);
 
 	/* "port" is allocated statically, so we shouldn't free it */


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