Re: [1/1] s390x/smp: fix detection of "running"

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On 3/27/20 7:01 PM, Christian Borntraeger wrote:
> 
> 
> On 27.03.20 17:55, David Hildenbrand wrote:
>> On 27.03.20 17:33, Christian Borntraeger wrote:
>>> On s390x hosts with a single CPU, the smp test case hangs (loops).
>>> The check is our restart has finished is wrong.
>>> Sigp sense running status checks if the CPU is currently backed by a
>>> real CPU. This means that on single CPU hosts a sigp sense running
>>> will never claim that a target is running. We need to check for not
>>> being stopped instead.
>>>
>>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>>> ---
>>>  lib/s390x/smp.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
>>> index 2555bf4..5ed8b7b 100644
>>> --- a/lib/s390x/smp.c
>>> +++ b/lib/s390x/smp.c
>>> @@ -128,7 +128,7 @@ static int smp_cpu_restart_nolock(uint16_t addr, struct psw *psw)
>>>  	 * The order has been accepted, but the actual restart may not
>>>  	 * have been performed yet, so wait until the cpu is running.
>>>  	 */
>>> -	while (!smp_cpu_running(addr))
>>> +	while (smp_cpu_stopped(addr))
>>>  		mb();
>>>  	cpu->active = true;
>>>  	return 0;
>>>
>>
>> Yeah, same as the other issue we fixed before. There is no trusting on
>> SIGP SENSE RUNNING STATUS.
>>
>> Can you please get rid of smp_cpu_running()? (looks like this was the
>> last user)
> 
> I think we should keep it and rename it to smp_cpu_running_status. This bug
> actually showed that we should be able to test this feature (which is used
> for spinlocks in Linux) somehow.
> 

We need to move it to the smp test case and at least test it but not use
it for any library stuff. When I do firmware testing with the unit tests
I need to be able to exercise as much sigp orders as possible.

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