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

[Davide Libenzi]

On Wed, 14 Mar 2007, Linus Torvalds wrote:

> 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.

Ack! Gotcha. Sigh! :)



- Davide


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