3.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Marek Roszko <[email protected]> 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 <[email protected]> Acked-by: Leilei Zhao <[email protected]> Signed-off-by: Nicolas Ferre <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/serial/atmel_serial.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1022,12 +1022,24 @@ static int atmel_startup(struct uart_por static void atmel_shutdown(struct uart_port *port) { struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); + + /* + * Clear out any scheduled tasklets before + * we destroy the buffers + */ + tasklet_kill(&atmel_port->tasklet); + /* - * Ensure everything is stopped. + * 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_p } /* - * 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
