On Sun, Sep 12, 2021 at 02:42:14PM +0200, Mateusz Jończyk wrote:
> Revert
> commit 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ")
> and add a comment.
>
> As described in a previous
> commit 66e4f4a9cc38 ("rtc: cmos: Use spin_lock_irqsave() in cmos_interrupt()")
> from February 2020:
>
> cmos_interrupt() isn't always called from hardirq context, so
> we must use spin_lock_irqsave() & co.
>
> Indeed, cmos_interrupt() is called from cmos_check_wkalrm(), which is
> called from cmos_resume() - apparently not in an interrupt context.
>
> A later
> commit 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ")
> did not take account of this and changed spin_lock_irqsave() to spin_lock().
> This may cause a deadlock as quoted in the body of
> commit 66e4f4a9cc38 ("rtc: cmos: Use spin_lock_irqsave() in cmos_interrupt()")
> mentioned earlier.
This regression was supposed to be fixed by
https://lore.kernel.org/linux-rtc/20210305122140.28774-1-chris@xxxxxxxxxxxxxxxxxx/
What happened to that one? I don't see it in Linus's tree...
--
Ville Syrjälä
Intel
