[PATCH 5/5] tty/serial: at91: correct the usage of tasklet
From: Leilei Zhao <hidden>
Date: 2015-02-26 07:04:39
Also in:
linux-serial, lkml
Subsystem:
microchip at91 serial driver, the rest, tty layer and serial drivers · Maintainers:
Richard Genoud, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
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 <redacted> Acked-by: Nicolas Ferre <redacted> --- 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 8d28210..39ec278 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));
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1.7.9.5