Re: [Xen-devel] [PATCH] Avoid panic when adjusting sedf paramete

To:	Jan Beulich <JBeulich@xxxxxxxx>, Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] [PATCH] Avoid panic when adjusting sedf parameters
From:	Keir Fraser <keir.xen@xxxxxxxxx>
Date:	Thu, 17 Nov 2011 13:48:36 +0000
Cc:	xen-devel@xxxxxxxxxxxxxxxxxxx
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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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Re: [Xen-devel] [PATCH] Avoid panic when adjusting sedf parameters