Re: [Xen-devel] [RFC][PATCH] walking the page lists needs the pa

To:	Jan Beulich <JBeulich@xxxxxxxxxx>
Subject:	Re: [Xen-devel] [RFC][PATCH] walking the page lists needs the page_alloc lock
From:	Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date:	Fri, 13 Aug 2010 08:10:01 +0100
Cc:	Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 13/08/2010 08:06, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>>> But then, to avoid a hanging system, these should be trylock-s
>>> rather than plain locks, shouldn't they?
>> 
>> Why? The handler is called in softirq context. It should be safe to spin.
> 
> Hmm, indeed. I was looking at others, and at least
> domain_dump_evtchn_info() also uses a trylock - apparently for
> no good reason.

Well, since you wrote that function, would you like me to switch
domain_dump_evtchn_info() to do a proper spin_lock()?

 -- Keir



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Re: [Xen-devel] [RFC][PATCH] walking the page lists needs the page_alloc