From 1e1257860fd10487795b782f1dbb5b5f2c203474 Mon Sep 17 00:00:00 2001 From: Leilei Zhao Date: Fri, 27 Feb 2015 16:07:18 +0800 Subject: [PATCH] tty/serial: at91: correct the usage of tasklet The tasklet may be scheduled and executed after serial port was shutdown, for example, DMA rx callback will schedule the tasklet while serial port is shutting down, especially serial port is sending and receiving data in a higher baud rate and it's killed by external program. In this case, tasklet_kill can only clear the current scheduling out, so tasklet should be disabled to prevent being executed in later scheduling. Otherwise, the tasklet executed after serial port was shutdown can lead to kernel crash. Signed-off-by: Leilei Zhao Acked-by: Nicolas Ferre Signed-off-by: Greg Kroah-Hartman --- 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 8fac877bc3d4..b45a4809031e 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1755,6 +1755,8 @@ static int atmel_startup(struct uart_port *port) if (retval) goto free_irq; + tasklet_enable(&atmel_port->tasklet); + /* * Initialize DMA (if necessary) */ @@ -1858,6 +1860,7 @@ static void atmel_shutdown(struct uart_port *port) * Clear out any scheduled tasklets before * we destroy the buffers */ + tasklet_disable(&atmel_port->tasklet); tasklet_kill(&atmel_port->tasklet); /* @@ -2251,6 +2254,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port, tasklet_init(&atmel_port->tasklet, atmel_tasklet_func, (unsigned long)port); + tasklet_disable(&atmel_port->tasklet); memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring)); -- GitLab