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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.11.11 at 14:52, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 17/11/2011 13:30, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>> which would now associate the else with the wrong (inner) if. One
>> possible solution that comes to mind would be
>> 
>> #define for_each_domain_in_cpupool(_d,_c) \
>>     for_each_domain_in_cpupool (_d) \
>>         if ((_d)->cpupool != (_c)) \
>>             continue; \
>>         else
>> 
>> but I think I had seen a more clever solution to this problem, but cannot
>> remember/locate it right now.
> 
> Given the gcc ({}) construction, you could do a double-loop:
>  for ( (_d) = rcu_dereference(domain_list);     \
>        (_d) != NULL;                            \
>        ({ while ((_d) = rcu_dereference((_d)->next_in_list != NULL)
>              if ((_d)->cpupool == (_c)) break;
>           (_d); }) )
> 
> A bit ugly. ;-) And I still worry about cpupool locking...

No - the very first domain would make into the body of the loop
without its pool being checked. The (adjusted) construct would
need to go into the checking (middle) portion of the for.

Jan


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