From: Tony Lindgren tony@atomide.com
[ Upstream commit 04e82793f068d2f0ffe62fcea03d007a8cdc16a7 ]
When we unbind a serial port hardware specific 8250 driver, the generic serial8250 driver takes over the port. After that we see an oops about 10 seconds later. This can produce the following at least on some TI SoCs:
Unhandled fault: imprecise external abort (0x1406) Internal error: : 1406 [#1] SMP ARM
Turns out that we may still have the serial port hardware specific driver port->pm in use, and serial8250_pm() tries to call it after the port specific driver is gone:
serial8250_pm [8250_base] from uart_change_pm+0x54/0x8c [serial_base] uart_change_pm [serial_base] from uart_hangup+0x154/0x198 [serial_base] uart_hangup [serial_base] from __tty_hangup.part.0+0x328/0x37c __tty_hangup.part.0 from disassociate_ctty+0x154/0x20c disassociate_ctty from do_exit+0x744/0xaac do_exit from do_group_exit+0x40/0x8c do_group_exit from __wake_up_parent+0x0/0x1c
Let's fix the issue by calling serial8250_set_defaults() in serial8250_unregister_port(). This will set the port back to using the serial8250 default functions, and sets the port->pm to point to serial8250_pm.
Signed-off-by: Tony Lindgren tony@atomide.com Link: https://lore.kernel.org/r/20230418101407.12403-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/8250/8250_core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 2675771a03a0d..d7afff1e7685f 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1138,6 +1138,7 @@ void serial8250_unregister_port(int line) uart->port.type = PORT_UNKNOWN; uart->port.dev = &serial8250_isa_devs->dev; uart->capabilities = 0; + serial8250_init_port(uart); serial8250_apply_quirks(uart); uart_add_one_port(&serial8250_reg, &uart->port); } else {