Re: [PATCH] serial: 8250: clear RX trigger callbacks when removing a port

[sashiko-bot@kernel.org]

> serial8250_unregister_port() removes the device supplied by a driver and
> normally re-registers the persistent slot as an unknown legacy port. The
> slot retains its RX trigger callbacks and sysfs attribute group, so the
> replacement rx_trig_bytes attribute can still call the removed driver's
> code. Unloading that driver leaves the callbacks pointing into freed
> module text.
> 
> Clear both callbacks after uart_remove_one_port() has drained the old
> sysfs users and before registering the fallback port. Its RX trigger
> attribute then uses the generic handlers, which reject a port without
> FIFO capabilities.
> 
> Also copy the callbacks unconditionally during registration. A replacement
> port without custom handlers must use the generic implementation instead
> of inheriting callbacks from the previous owner of the slot.
> 
> Fixes: 8a6c543cf8b3 ("serial: 8250: allow UART drivers to override rx_trig_bytes handling")
> Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

Sashiko has reviewed this patch and found no issues.

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