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serial: 8250: lock port for UART_IER access in omap8250_irq() 

[ Upstream commit 25614735a6 ]

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: 1fe0e1fa32 ("serial: 8250_omap: Handle optional overrun-throttle-ms property")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230525093159.223817-8-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
John Ogness 2023-05-25 11:37:58 +02:06 committed by Greg Kroah-Hartman
parent 3a1ab191e0
commit 9c4f52b618
1 changed files with 3 additions and 2 deletions
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5
drivers/tty/serial/8250/8250_omap.c
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@ -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) { if ((lsr & UART_LSR_OE) && up->overrun_backoff_time_ms > 0) {
unsigned long delay; unsigned long delay;
/* Synchronize UART_IER access against the console. */
spin_lock(&port->lock);
up->ier = port->serial_in(port, UART_IER); up->ier = port->serial_in(port, UART_IER);
if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
spin_lock(&port->lock);
port->ops->stop_rx(port); port->ops->stop_rx(port);
spin_unlock(&port->lock);
} else { } else {
/* Keep restarting the timer until /* Keep restarting the timer until
* the input overrun subsides. * the input overrun subsides.
*/ */
cancel_delayed_work(&up->overrun_backoff); cancel_delayed_work(&up->overrun_backoff);
} }
spin_unlock(&port->lock);
delay = msecs_to_jiffies(up->overrun_backoff_time_ms); delay = msecs_to_jiffies(up->overrun_backoff_time_ms);
schedule_delayed_work(&up->overrun_backoff, delay); schedule_delayed_work(&up->overrun_backoff, delay);