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SubjectRe: timer_bh behaviour incorrect for 2.2.13?

On Thu, 9 Dec 1999, William Montgomery wrote:

> > there is one race here that is subtle: if a bottom-half is marked _while_
> > do_bottom_half is executing, then do_bottom_half might not notice this,
> > and we miss the event.

> I will try your patch but it seems unlikely since run_bottom_halves
> is protected by __sti(); / __cli();. Since interrupts are disabled
> I dont see how a timer IRQ could occur while run_bottom_halves is
> executing.

bottom halves can still enable interrupts, so it can indeed happen
(more so on SMP) that a BH gets marked active while a BH is running.

> Sounds like Andrea also has some idea about what might be happening.

no, he noticed the same race.

-- mingo

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