This is a note to let you know that I've just added the patch titled
serial: 8250: lock port for UART_IER access in omap8250_irq()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-8250-lock-port-for-uart_ier-access-in-omap825.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b5cc2057c8b0cdb329c484aa336292bac67b9a5a
Author: John Ogness <john.ogness@xxxxxxxxxxxxx>
Date: Thu May 25 11:37:58 2023 +0206
serial: 8250: lock port for UART_IER access in omap8250_irq()
[ Upstream commit 25614735a647693c1260f253dc3ab32127697806 ]
omap8250_irq() accesses UART_IER. This register is modified twice
by each console write (serial8250_console_write()) under the port
lock. omap8250_irq() must also take the port lock to guanentee
synchronized access to UART_IER.
Since the port lock is already being taken for the stop_rx() callback
and since it is safe to call cancel_delayed_work() while holding the
port lock, simply extend the port lock region to include UART_IER
access.
Fixes: 1fe0e1fa3209 ("serial: 8250_omap: Handle optional overrun-throttle-ms property")
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Tony Lindgren <tony@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230525093159.223817-8-john.ogness@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 7ecd2d379292b..17a230281ebe0 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -639,17 +639,18 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id)
if ((lsr & UART_LSR_OE) && up->overrun_backoff_time_ms > 0) {
unsigned long delay;
+ /* Synchronize UART_IER access against the console. */
+ spin_lock(&port->lock);
up->ier = port->serial_in(port, UART_IER);
if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
- spin_lock(&port->lock);
port->ops->stop_rx(port);
- spin_unlock(&port->lock);
} else {
/* Keep restarting the timer until
* the input overrun subsides.
*/
cancel_delayed_work(&up->overrun_backoff);
}
+ spin_unlock(&port->lock);
delay = msecs_to_jiffies(up->overrun_backoff_time_ms);
schedule_delayed_work(&up->overrun_backoff, delay);
