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serial: 8250: Fix oops for port->pm on uart_change_pm()

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[ Upstream commit dfe2aeb226fd5e19b0ee795f4f6ed8bc494c1534 ]

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@atomide.com>
Link: https://lore.kernel.org/r/20230804131553.52927-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tony Lindgren 2023-08-04 16:15:51 +03:00 committed by Greg Kroah-Hartman
parent 03a7f213af
commit bd70d0b280
1 changed files with 1 additions and 0 deletions
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drivers/tty/serial/8250/8250_port.c
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@ -3231,6 +3231,7 @@ void serial8250_init_port(struct uart_8250_port *up)
struct uart_port *port = &up->port;
spin_lock_init(&port->lock);
port->pm = NULL;
port->ops = &serial8250_pops;
port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);