Re: 2.6.19-rc6: known regressions (v4)

Pavel Emelianov
2006-11-22T09:50:21Z

> I really think this is wrong.
>
> The original patch was wrong, and the _real_ problem is in __do_IRQ() that
> got the desc->lock too early.
>
> I _think_ the correct fix is to simply revert the broken commit, and fix
> the _one_ place that called "misnote_interrupt()" with the lock held.
>
> Something like this..
>
> I also think that the real fix will be to move the whole
>
> if (!noirqdebug)
> note_interrupt(irq, desc, action_ret);
>
>
> into handle_IRQ_event itself, since every caller (except for
> "misrouted_irq()" itself, and that should probably be done separately)
> should always do it. Right now we have a lot of people that just do
>
> action_ret = handle_IRQ_event(irq, action);
> if (!noirqdebug)
> note_interrupt(irq, desc, action_ret);
>
> explicitly.
>
> The only thing that keeps us from doing that is that we don't pass in
> "desc", but we should just do that.
>
> But in the meantime, this appears to be the minimal fix. Can people please
> test and verify?

This works for me, but is this normal that desc's fields are
modified non-atomically in note_interrupt()?

And one more thing - report_bad_irq() traverses desc->action
list without any locking either.