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Date: Fri, 21 Feb 2014 12:10:17 +0000
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20140221121017.GD2483@work-vm>
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Subject: Re: [Qemu-devel] [PATCH v2] XBZRLE: Fix qemu crash when resize the
	xbzrle cache
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To: "Gonglei (Arei)" <arei.gonglei@huawei.com>
Cc: "chenliang (T)" <chenliang88@huawei.com>, "owasserm@redhat.com" <owasserm@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Juan Quintela <quintela@redhat.com>

* Gonglei (Arei) (arei.gonglei@huawei.com) wrote:
> Hi,

<snip>

> > > +static void XBZRLE_cache_lock(void)
> > > +{
> > > +    qemu_mutex_lock(&XBZRLE.lock);
> > > +}
> > > +
> > > +static void XBZRLE_cache_unlock(void)
> > > +{
> > > +    qemu_mutex_unlock(&XBZRLE.lock);
> > > +}
> > > +
> > 
> > You might want to make these only bother with the lock if xbzrle is enabled
> > - however actually, I think it's probably just best to keep them as is,
> > and simple.
> To be honest, we can't follow your meaning. Can you explain it in detail. 

These two functions are called from a few places, including ram_save_block
even if xbzrle isn't enabled; I was just suggesting you might not want
to check the lock if xbzrle is disabled; however, I think it's simpler
to leave it as is, and doubt the overhead is worth the complexity.

Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK