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Re: [Xen-devel] [PATCH] Avoid panic when adjusting sedf parameters
- To: Jan Beulich <JBeulich@xxxxxxxx>, Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
- From: Keir Fraser <keir.xen@xxxxxxxxx>
- Date: Thu, 17 Nov 2011 13:48:36 +0000
- Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 17 Nov 2011 13:49:30 +0000
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- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
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- Thread-topic: [Xen-devel] [PATCH] Avoid panic when adjusting sedf parameters
On 17/11/2011 13:30, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>> +#define for_each_domain_in_cpupool(_d,_c) \
>> + for ( (_d) = rcu_dereference(domain_list); \
>> + (_d) != NULL; \
>> + (_d) = rcu_dereference((_d)->next_in_list )) \
>
> Wouldn't this, up to here, simply be for_each_domain()?
>
>> + if ((_d)->cpupool == (_c))
>
> This is dangerous - consider code like
I also wonder (and this is true for the existing open-coded versions too)
whether we have sufficient locking around use of d->cpupool? Do these loops
hold enough locks to ensure that d->cpupool doesn't change under their feet?
-- Keir
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