Manfred Spraul:
>I think in_irq() and in_interrupt() should check the cpu interrupt flag
>and return TRUE if the per-cpu interrupts are disabled.
>
>The current behavious is just weird:
> spin_lock_bh();
> in_interrupt(); --> true
> spin_unlock_bh();
> spin_lock_irq();
> in_interrupt(); --> false
> spin_unlock_irq();
I see. Instead of checking the interrupt flag in in_irq(), spin_lock_irq
could also simply increment the local_irq_count, just like spin_lock_bh
increments the local_bh_count.
>> Whether this same situation can explain the deadlocks seen on
>> other platforms depends on whether the drivers used there exhibit
>> similar locking behaviours as the QDIO driver, of course.
>
>It should be possible to detect that automatically: if
>dev_kfree_skb_any() is called outside irq context with disabled per-cpu
>interrupts then it's probably due to a spin_lock_irq() and could
>deadlock.
This would definitely solve the deadlock in our case. However, I'm not
sure this doesn't have some adverse effect on other code; e.g. there are
quite a few routines that use if (!in_interrupt()) as a bug-check, and
some might possibly be called from inside a spin_lock_irq ...
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
-- Dr. Ulrich Weigand Linux for S/390 Design & Development IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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