linux-kernel - RE: epoll and closed file descriptors

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Message-ID: <alpine.DEB.2.00.0909161726090.3124@makko.or.mcafeemobile.com>
Date:	Wed, 16 Sep 2009 17:30:18 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Gilad Benjamini <gilad@...ornetworks.com>
cc:	'Linux Kernel Mailing List' <linux-kernel@...r.kernel.org>
Subject: RE: epoll and closed file descriptors

On Wed, 16 Sep 2009, Gilad Benjamini wrote:

> I would, but epoll is preventing me from doing so.
> Early in sys_epoll_ctl there are these lines
> 
>   file = fget(epfd);
>   if (!file)
>     goto error_return;
> 
> Leaving me in a kind of dead lock

The 'epfd' in there, is the _epoll fd_, which, if fget() fails, means you 
close it.
You see likely failing the 'tfile = fget(fd)' (of course, you closed it), 
so if someone else keeps the socket open and you have no chance in telling 
it to drop it (really?), you need to remove the socket from the set before 
closing it.

- Davide

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