[PATCH] um: Add winch to winch_handlers before registering winch IRQ

[Johannes Berg]

On Thu, 2024-03-07 at 11:49 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu at huawei.com>
> 
> Registering a winch IRQ is racy, an interrupt may occur before the winch is
> added to the winch_handlers list.
> 
> If that happens, register_winch_irq() adds to that list a winch that is
> scheduled to be (or has already been) freed, causing a panic later in
> winch_cleanup().
> 
> Avoid the race by adding the winch to the winch_handlers list before
> registering the IRQ, and rolling back if um_request_irq() fails.
> 

Reviewed-by: Johannes Berg <johannes at sipsolutions.net>

johannes