[PATCH v6 1/3] serial: 8250: fix deadlock in serial8250_register_ports()

[Hui Peng]

In serial8250_register_ports(), mutex_lock(&hash_mutex) is acquired while
holding spinlock_t serial_port_lock during IRQ chain registration:

  spin_lock_irqsave(&serial_port_lock, flags);
  mutex_lock(&hash_mutex);

Acquiring a sleeping mutex while holding a spinlock causes a
sleeping-while-atomic bug and potential deadlock.

Replace mutex_lock(&hash_mutex) with spin_lock_irqsave() in
serial8250_register_ports().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Assisted-by: LLM
Signed-off-by: Hui Peng <benquike@xxxxxxxxx>
---
 drivers/tty/serial/8250/8250_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 9e4f5a2a2eaa..f64a1b0a2eaa 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -102,9 +102,9 @@ static void serial8250_register_ports(struct uart_driver *drv,
 	struct uart_8250_port *up;

 	for (i = 0; i < nr; i++) {
-		up = &serial8250_ports[i];
+		up = &serial8250_ports[i];
 		up->port.dev = dev;
 	}
 }