| Date | Sun, 7 Aug 2022 12:38:33 -0300 | Subject | Re: [PATCH v2 03/13] firmware: google: Test spinlock on panic path to avoid lockups | From | "Guilherme G. Piccoli" <> |
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On 19/07/2022 16:53, Guilherme G. Piccoli wrote: > Currently the gsmi driver registers a panic notifier as well as > reboot and die notifiers. The callbacks registered are called in > atomic and very limited context - for instance, panic disables > preemption and local IRQs, also all secondary CPUs (not executing > the panic path) are shutdown. > > With that said, taking a spinlock in this scenario is a dangerous > invitation for lockup scenarios. So, fix that by checking if the > spinlock is free to acquire in the panic notifier callback - if not, > bail-out and avoid a potential hang. > > Fixes: 74c5b31c6618 ("driver: Google EFI SMI") > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: David Gow <davidgow@google.com> > Cc: Evan Green <evgreen@chromium.org> > Cc: Julius Werner <jwerner@chromium.org> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> > > --- > > V2: > - do not use spin_trylock anymore, to avoid messing with > non-panic paths; now we just check the spinlock state in > the panic notifier before taking it. Thanks Evan for the > review/idea! > > drivers/firmware/google/gsmi.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > [...]
Hi Evan, do you think this one is good now, based on your previous review?
Appreciate any feedback! Cheers,
Guilherme
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