diff options
| author | Marek Roszko <mark.roszko@gmail.com> | 2014-01-07 11:45:06 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-06 11:05:47 -0800 |
| commit | 3a9694557f5aefc34a08bddcfcbd0ca12d8dec9a (patch) | |
| tree | 1f8442e58739d0ee9e009f050c07c8f150f8aa62 | |
| parent | b135ecd41b9e19dda09654086a54f9cd13ab89b3 (diff) | |
tty/serial: at91: Handle shutdown more safely
commit 0cc7c6c7916b1b6f34350ff1473b80b9f7e459c0 upstream.
Interrupts were being cleaned up late in the shutdown handler, it is possible
that an interrupt can occur and schedule a tasklet that runs after the port is
cleaned up. There is a null dereference due to this race condition with the
following stacktrace:
[<c02092b0>] (atmel_tasklet_func+0x514/0x814) from [<c001fd34>] (tasklet_action+0x70/0xa8)
[<c001fd34>] (tasklet_action+0x70/0xa8) from [<c001f60c>] (__do_softirq+0x90/0x144)
[<c001f60c>] (__do_softirq+0x90/0x144) from [<c001fa18>] (irq_exit+0x40/0x4c)
[<c001fa18>] (irq_exit+0x40/0x4c) from [<c000e298>] (handle_IRQ+0x64/0x84)
[<c000e298>] (handle_IRQ+0x64/0x84) from [<c000d6c0>] (__irq_svc+0x40/0x50)
[<c000d6c0>] (__irq_svc+0x40/0x50) from [<c0208060>] (atmel_rx_dma_release+0x88/0xb8)
[<c0208060>] (atmel_rx_dma_release+0x88/0xb8) from [<c0209740>] (atmel_shutdown+0x104/0x160)
[<c0209740>] (atmel_shutdown+0x104/0x160) from [<c0205e8c>] (uart_port_shutdown+0x2c/0x38)
Signed-off-by: Marek Roszko <mark.roszko@gmail.com>
Acked-by: Leilei Zhao <leilei.zhao@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/atmel_serial.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index ed7cd378b83..ff58d288c9c 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1022,12 +1022,24 @@ static int atmel_startup(struct uart_port *port) static void atmel_shutdown(struct uart_port *port) { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + /* - * Ensure everything is stopped. + * Clear out any scheduled tasklets before + * we destroy the buffers + */ + tasklet_kill(&atmel_port->tasklet); + + /* + * Ensure everything is stopped and + * disable all interrupts, port and break condition. */ atmel_stop_rx(port); atmel_stop_tx(port); + UART_PUT_CR(port, ATMEL_US_RSTSTA); + UART_PUT_IDR(port, -1); + + /* * Shut-down the DMA. */ @@ -1054,12 +1066,6 @@ static void atmel_shutdown(struct uart_port *port) } /* - * Disable all interrupts, port and break condition. - */ - UART_PUT_CR(port, ATMEL_US_RSTSTA); - UART_PUT_IDR(port, -1); - - /* * Free the interrupt */ free_irq(port->irq, port); |