Re: 2.6.19-rc3-git7: scsi_device_unbusy: inconsistent lock state

[Ingo Molnar <mingo@elte.hu>]

* Jens Axboe <jens.axboe@oracle.com> wrote:

> > > things may be allocated from that path, so we pass gfp_mask around. I'll
> > > double check it tonight, but I don't currently see what could be wrong.
> > > Would lockdep complain about:
> > > 
> > >         spin_lock_irqsave(lock, flags);
> > >         ...
> > >         spin_unlock_irq(lock);
> > >         ...
> > >         spin_lock_irq(lock);
> > >         ...
> > >         spin_unlock_irqrestore(lock, flags);
> > 
> > this is fine for lockdep IF and only IF there is no "out lock" held
> > around this that requires irqs to be off. So if you do
> > 
> > spin_lock_irqsave(lock1, flags);
> > ...
> > spin_lock_irqsave(lock2, flags);
> > spin_unlock_irq(lock2)
> > ...
> > 
> > then lockdep WILL complain, and rightfully so, about a violation since
> > lock1 gets violated here ;)
> 
> Naturally, that is a bug fair and simple, nothing to do with lockdep.

well, finding such locking bugs is the main purpose of lockdep, so there 
is at least some connection i'd say ;-)

	Ingo
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