[PATCH v3 3/9] serial: qcom-geni: fix shutdown race

[Johan Hovold]

A commit adding back the stopping of tx on port shutdown failed to add
back the locking which had also been removed by commit e83766334f96
("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART
shutdown").

Holding the port lock is needed to serialise against the console code,
which may update the interrupt enable register and access the port
state.

Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
Fixes: 947cc4ecc06c ("serial: qcom-geni: fix soft lockup on sw flow control and suspend")
Cc: stable@xxxxxxxxxxxxxxx	# 6.3
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
---
 drivers/tty/serial/qcom_geni_serial.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 2e4a5361f137..87cd974b76bf 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1114,10 +1114,12 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
 {
 	disable_irq(uport->irq);
 
+	uart_port_lock_irq(uport);
 	qcom_geni_serial_stop_tx(uport);
 	qcom_geni_serial_stop_rx(uport);
 
 	qcom_geni_serial_cancel_tx_cmd(uport);
+	uart_port_unlock_irq(uport);
 }
 
 static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
-- 
2.45.2