Commit 8bc661bf authored by Marek Roszko's avatar Marek Roszko Committed by Greg Kroah-Hartman

tty/serial: at91: disable uart timer at start of shutdown

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: default avatarMarek Roszko <mark.roszko@gmail.com>
Cc: stable <stable@vger.kernel.org> # v3.12
[nicolas.ferre@atmel.com: modify commit message, call setup_timer() in any case]
Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3685f19e
......@@ -825,9 +825,6 @@ 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)
......@@ -1229,9 +1226,6 @@ 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)
......@@ -1604,12 +1598,13 @@ static int atmel_startup(struct uart_port *port)
/* enable xmit & rcvr */
UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);
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);
if (atmel_use_pdc_rx(port)) {
/* set UART timeout */
if (!atmel_port->is_usart) {
mod_timer(&atmel_port->uart_timer,
jiffies + uart_poll_timeout(port));
/* set USART timeout */
......@@ -1624,9 +1619,6 @@ 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 */
......@@ -1651,6 +1643,12 @@ 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
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment