From: Juan Quintela <quintela@redhat.com>
To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, kwolf@redhat.com,
zhanghailiang <zhang.zhanghailiang@huawei.com>,
peterx@redhat.com, mreitz@redhat.com, stefanha@redhat.com,
Peter Maydell <peter.maydell@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
jsnow@redhat.com
Subject: Re: [Qemu-devel] [PATCH] migration: Fix race of image locking between src and dst
Date: Mon, 19 Jun 2017 17:26:03 +0200 [thread overview]
Message-ID: <8760fsatis.fsf@secure.mitica> (raw)
In-Reply-To: <20170616160658.32290-1-famz@redhat.com> (Fam Zheng's message of "Sat, 17 Jun 2017 00:06:58 +0800")
Fam Zheng <famz@redhat.com> wrote:
> Previously, dst side will immediately try to lock the write byte upon
> receiving QEMU_VM_EOF, but at src side, bdrv_inactivate_all() is only
> done after sending it. If the src host is under load, dst may fail to
> acquire the lock due to racing with the src unlocking it.
>
> Fix this by hoisting the bdrv_inactivate_all() operation before
> QEMU_VM_EOF.
>
> N.B. A further improvement could possibly be done to cleanly handover
> locks between src and dst, so that there is no window where a third QEMU
> could steal the locks and prevent src and dst from running.
>
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
next prev parent reply other threads:[~2017-06-19 15:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-16 16:06 [Qemu-devel] [PATCH] migration: Fix race of image locking between src and dst Fam Zheng
2017-06-19 14:49 ` Daniel P. Berrange
2017-06-19 15:27 ` Peter Maydell
2017-06-19 15:28 ` Daniel P. Berrange
2017-06-19 15:26 ` Juan Quintela [this message]
2017-06-19 16:54 ` Peter Maydell
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