4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tony Lindgren <tony@xxxxxxxxxxx>
commit dfe2aeb226fd5e19b0ee795f4f6ed8bc494c1534 upstream.
Unloading a hardware specific 8250 driver can produce error "Unable to
handle kernel paging request at virtual address" about ten seconds after
unloading the driver. This happens on uart_hangup() calling
uart_change_pm().
Turns out commit 04e82793f068 ("serial: 8250: Reinit port->pm on port
specific driver unbind") was only a partial fix. If the hardware specific
driver has initialized port->pm function, we need to clear port->pm too.
Just reinitializing port->ops does not do this. Otherwise serial8250_pm()
will call port->pm() instead of serial8250_do_pm().
Fixes: 04e82793f068 ("serial: 8250: Reinit port->pm on port specific driver unbind")
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230804131553.52927-1-tony@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3191,6 +3191,7 @@ void serial8250_init_port(struct uart_82
struct uart_port *port = &up->port;
spin_lock_init(&port->lock);
+ port->pm = NULL;
port->ops = &serial8250_pops;
up->cur_iotype = 0xFF;
