Re: [patch 13/13] signalfd/timerfd/asyncfd v5 - KAIO asyncfd support(example/maybe-broken) ...

[Linus Torvalds]

On Wed, 14 Mar 2007, Davide Libenzi wrote:
> >
> > That won't work.  aio_complete() is supposed to be irq safe.
> 
> Can you point me to a kernel path that ends up calling aio_complete() in a 
> do-not-sleep mode?

All of them.

It's called from dio_bio_end_aio(), which is the bi_end_io function for an 
AIO action. Which in turn is called at IO completion time. 

Which is basically _always_ interrupt context.

So you cannot sleep. It's not about holding spinlocks (which it might well 
do as well). It's about a much more fundamental issue: you can only sleep 
in process context, not from interrupts.

		Linus
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