Re: xenstored file descriptor leak

From: "Jürgen Groß" <jgross@suse.com>
To: Manuel Bouyer <bouyer@antioche.eu.org>
Cc: xen-devel@lists.xen.org
Subject: Re: xenstored file descriptor leak
Date: Wed, 3 Feb 2021 09:21:32 +0100	[thread overview]
Message-ID: <89ddaac0-eb05-8ddb-465a-60d78e4009eb@suse.com> (raw)
In-Reply-To: <20210203081621.GD445@antioche.eu.org>

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On 03.02.21 09:16, Manuel Bouyer wrote:
> On Wed, Feb 03, 2021 at 09:05:27AM +0100, Jürgen Groß wrote:
>>>> [...]
>>>> Yes, I think this is a good idea.
>>>
>>> Well, after some sleep I don't think it is. We should always keep at last
>>> POLLIN or we will never notice a socket close otherwise.
>>
>> Adding the fd of an ignored socket connection to the list is the real
>> problem here. Why should that be done?
> 
> If we don't do it, we never notice when the socket is closed and the file
> descriptor will stay forever. When I tried it, I had about 50 zombie
> file descriptors open in xenstored, after starting only 2 domains.

This shouldn't happen in case we are closing the socket actively.

In the end we should just do a talloc_free(conn) in
ignore_connection() if it is a socket based one. This should revert
the critical modification of the XSA-115 fixes for sockets while
keeping the desired effect for domain connections.

Juergen

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