Re: [patch] eventfd - remove fput() call from possible IRQ context (3rd rev)

[Jeff Moyer]

Davide Libenzi <davidel@xxxxxxxxxxxxxxx> writes:

> The following patch remove a possible source of fput() call from inside 
> IRQ context. Myself, like Eric, wasn't able to reproduce an fput() call 
> from IRQ context, but Jeff said he was able to, with the attached test 
> program. Independently from this, the bug is conceptually there, so we 
> might be better off fixing it.
> This patch adds an optimization similar to the one we already do on 
> ->ki_filp, on ->ki_eventfd. Playing with ->f_count directly is not pretty 
> in general, but the alternative here would be to add a brand new delayed 
> fput() infrastructure, that I'm not sure is worth it.
>
>
> On Sun, 15 Mar 2009, Benjamin LaHaise wrote:
>
>> This looks reasonably sane, the only concern I have with it is that I think 
>> it logically makes more sense to use the same convention for fi_filp and 
>> ki_eventfd, as the different in IS_ERR vs checking for NULL is a bit 
>> confusing.  Aside from that, it looks like it should fix the problem 
>> correctly.
>
> Makes sense.
>
>
>
> Signed-off-by: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>

Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
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