diff options
| author | Marek Roszko <mark.roszko@gmail.com> | 2014-01-10 10:33:11 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-06 11:22:17 -0800 |
| commit | 2d328c95bef7063598b5663f2024d3e245d19ffb (patch) | |
| tree | 082528509c30f5792029e7e4a25556d4f6feab81 /drivers/tty | |
| parent | 6bdf61a056192cf6bb4cf13a1bae5e9b7bc9c4e2 (diff) | |
tty/serial: at91: disable uart timer at start of shutdown
commit 8bc661bfc0c2d221e209f4205bdaaf574d50100c upstream.
The uart timer will schedule a tasklet when it fires. It is possible that it
can fire inside _shutdown before it is killed in the dma and pdc cleanup
routines. This causes a tasklet that exists after the port is shutdown, so when
the kernel finally executes it, it panics as the tty port is NULL.
This is a somewhat rare condition but its possible if a program keeps on
opening/closing the port. It has been observed in particular with systemd
boot messages that were causing a kernel panic because of this behavior.
Moving the timer deletion to the beginning of the function stops a tasklet from
being scheduled unexpectedly.
Signed-off-by: Marek Roszko <mark.roszko@gmail.com>
[nicolas.ferre@atmel.com: modify commit message, call setup_timer() in any case]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/atmel_serial.c | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 2e2a1f3622bb..41bb8387e80d 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -824,9 +824,6 @@ static void atmel_release_rx_dma(struct uart_port *port) atmel_port->desc_rx = NULL; atmel_port->chan_rx = NULL; atmel_port->cookie_rx = -EINVAL; - - if (!atmel_port->is_usart) - del_timer_sync(&atmel_port->uart_timer); } static void atmel_rx_from_dma(struct uart_port *port) @@ -1228,9 +1225,6 @@ static void atmel_release_rx_pdc(struct uart_port *port) DMA_FROM_DEVICE); kfree(pdc->buf); } - - if (!atmel_port->is_usart) - del_timer_sync(&atmel_port->uart_timer); } static void atmel_rx_from_pdc(struct uart_port *port) @@ -1587,12 +1581,13 @@ static int atmel_startup(struct uart_port *port) /* enable xmit & rcvr */ UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN); + setup_timer(&atmel_port->uart_timer, + atmel_uart_timer_callback, + (unsigned long)port); + if (atmel_use_pdc_rx(port)) { /* set UART timeout */ if (!atmel_port->is_usart) { - setup_timer(&atmel_port->uart_timer, - atmel_uart_timer_callback, - (unsigned long)port); mod_timer(&atmel_port->uart_timer, jiffies + uart_poll_timeout(port)); /* set USART timeout */ @@ -1607,9 +1602,6 @@ static int atmel_startup(struct uart_port *port) } else if (atmel_use_dma_rx(port)) { /* set UART timeout */ if (!atmel_port->is_usart) { - setup_timer(&atmel_port->uart_timer, - atmel_uart_timer_callback, - (unsigned long)port); mod_timer(&atmel_port->uart_timer, jiffies + uart_poll_timeout(port)); /* set USART timeout */ @@ -1635,6 +1627,12 @@ static void atmel_shutdown(struct uart_port *port) struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); /* + * Prevent any tasklets being scheduled during + * cleanup + */ + del_timer_sync(&atmel_port->uart_timer); + + /* * Clear out any scheduled tasklets before * we destroy the buffers */ |