[Xen-devel] Re: [PATCH]x86: Fix possible S3 suspend hangs

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Oh, don't worry about it. It's more obvious than I first thought!

 -- Keir

On 12/03/2010 07:20, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

> Not doubting this race exists, but could you briefly give an example of an
> offlining scenario that would hit the hang? And explain the result: is it
> that the offliner thinks the operation doesn't complete and spins forever in
> __cpu_die()?
> 
>  -- Keir
> 
> On 12/03/2010 03:42, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote:
> 
>> X86: Fix possible S3 suspend hangs
>> 
>> It is possible for cpu to become offlined before irq disabled in idle loop,
>> which will cause this cpu stay in C state and can't wakeup to play dead.
>> 
>> Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>
>> Signed-off-by: Yu Ke <ke.yu@xxxxxxxxx>
>> 
>> diff -r 132ac04cbdba xen/arch/x86/acpi/cpu_idle.c
>> --- a/xen/arch/x86/acpi/cpu_idle.c Tue Mar 09 18:18:19 2010 +0000
>> +++ b/xen/arch/x86/acpi/cpu_idle.c Fri Mar 12 11:07:43 2010 +0800
>> @@ -268,7 +268,8 @@ static void acpi_processor_idle(void)
>>       */
>>      local_irq_disable();
>>  
>> -    if ( softirq_pending(smp_processor_id()) )
>> +    if ( softirq_pending(smp_processor_id()) ||
>> +         cpu_is_offline(smp_processor_id()) )
>>      {
>>          local_irq_enable();
>>          sched_tick_resume();
>> diff -r 132ac04cbdba xen/arch/x86/domain.c
>> --- a/xen/arch/x86/domain.c Tue Mar 09 18:18:19 2010 +0000
>> +++ b/xen/arch/x86/domain.c Fri Mar 12 11:12:24 2010 +0800
>> @@ -82,7 +82,8 @@ static void default_idle(void)
>>  static void default_idle(void)
>>  {
>>      local_irq_disable();
>> -    if ( !softirq_pending(smp_processor_id()) )
>> +    if ( !softirq_pending(smp_processor_id()) &&
>> +         cpu_online(smp_processor_id()) )
>>          safe_halt();
>>      else
>>          local_irq_enable();
> 



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