From: Jim Fehlig <jfehlig@suse.com>
To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Bamvor Jian Zhang <bjzhang@suse.com>,
Ian Campbell <Ian.Campbell@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH] fix race condition between libvirtd event handling and libxl fd deregister
Date: Mon, 10 Dec 2012 16:56:33 -0700 [thread overview]
Message-ID: <50C676B1.4070609@suse.com> (raw)
In-Reply-To: <20677.47995.298291.120095@mariner.uk.xensource.com>
Ian Jackson wrote:
> Ian Campbell writes ("Re: [PATCH] fix race condition between libvirtd event handling and libxl fd deregister"):
>
>> I took Bamvor's most recent response to mean that a per-event lock was
>> already in place in libvirt and inferred that this was the reason why
>> the originally proposed one line fix worked for them. Perhaps I
>> misunderstood?
>>
>
> Yes, I think that's what Bamvor meant but I don't think it's correct
> that such a lock eliminates the race. libvirt has to release that
> lock before making the callback (to follow the libxl locking rules
> which are necessary to avoid deadlock).
>
And it does. The event loop lock is released just before invoking the
callback, and re-acquired just after the callback returns.
Jim
next prev parent reply other threads:[~2012-12-10 23:56 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 7:16 [PATCH] fix race condition between libvirtd event handling and libxl fd deregister Bamvor Jian Zhang
2012-11-23 9:43 ` Ian Campbell
2012-11-26 23:22 ` Jim Fehlig
2012-11-27 10:03 ` Ian Campbell
2012-11-27 19:08 ` Ian Jackson
2012-11-28 11:25 ` Ian Campbell
2012-12-06 16:11 ` 答复： " Bamvor Jian Zhang
2012-12-07 19:11 ` Ian Jackson
2012-12-07 19:15 ` [PATCH 1/2] libxl: fix stale fd event callback race Ian Jackson
2012-12-07 19:22 ` Ian Jackson
2012-12-07 19:15 ` [PATCH 2/2] libxl: fix stale timeout " Ian Jackson
2012-12-07 19:21 ` [PATCH 1/2] libxl: fix stale fd " Ian Jackson
2012-12-07 19:21 ` [PATCH 2/2] libxl: fix stale timeout " Ian Jackson
2012-12-10 10:19 ` [PATCH] fix race condition between libvirtd event handling and libxl fd deregister Ian Campbell
2012-12-10 10:37 ` Ian Jackson
2012-12-10 16:56 ` Ian Jackson
2012-12-10 16:57 ` [PATCH 1/2] libxl: fix stale fd event callback race Ian Jackson
2012-12-11 22:35 ` Jim Fehlig
2012-12-12 17:04 ` Ian Jackson
2012-12-12 17:20 ` Jim Fehlig
2012-12-10 16:57 ` [PATCH 2/2] libxl: fix stale timeout " Ian Jackson
2012-12-11 22:53 ` Jim Fehlig
2012-12-12 17:14 ` Ian Jackson
2012-12-12 17:16 ` Ian Jackson
2012-12-12 17:26 ` Jim Fehlig
2012-12-12 17:37 ` Ian Jackson
2012-12-12 18:01 ` Jim Fehlig
2012-12-13 10:29 ` Ian Campbell
2012-12-13 13:12 ` Ian Jackson
2012-12-13 15:53 ` Jim Fehlig
2012-12-13 15:58 ` Ian Jackson
2012-12-13 16:53 ` Jim Fehlig
2012-12-13 13:07 ` Ian Jackson
2012-12-13 15:41 ` Jim Fehlig
2012-12-13 15:51 ` Ian Jackson
2012-12-13 15:57 ` Jim Fehlig
2012-12-11 10:19 ` [PATCH] fix race condition between libvirtd event handling and libxl fd deregister Bamvor Jian Zhang
2012-12-11 11:20 ` Ian Jackson
2013-01-11 11:41 ` Ian Campbell
2013-01-11 17:51 ` Jim Fehlig
2013-01-15 10:40 ` Ian Campbell
2013-01-15 17:02 ` Jim Fehlig
2013-01-21 19:37 ` Jim Fehlig
2013-01-22 10:21 ` Ian Campbell
2012-12-10 23:56 ` Jim Fehlig [this message]
2012-12-11 11:18 ` Ian Jackson
2012-12-06 16:06 ` 答复： " Bamvor Jian Zhang
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