Re: [PATCH v4 2/2] sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS

[Dietmar Eggemann]

On 26/07/2021 15:56, Quentin Perret wrote:
> On Thursday 22 Jul 2021 at 10:47:33 (+0200), Dietmar Eggemann wrote:

[...]

>>> @@ -7393,6 +7403,8 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
>>>  	rcu_read_unlock();
>>>  
>>>  	if (likely(p)) {
>>> +		if (attr.sched_flags & SCHED_FLAG_KEEP_PARAMS)
>>> +			get_params(p, &attr);
>>
>> SCHED_FLAG_KEEP_PARAMS is handled here but SCHED_FLAG_KEEP_POLICY
>> outside (before) the `if (likely(p))`?
> 
> Because I need to dereference p while SCHED_FLAG_KEEP_POLICY doesn't :)

Ah, true. Looked weird though.
But then the SCHED_FLAG_KEEP_POLICY condition can be placed closer to
the SCHED_FLAG_KEEP_PARAMS condition. We don't have to set
SETPARAM_POLICY if p == NULL.

>>>  		retval = sched_setattr(p, &attr);
>>>  		put_task_struct(p);
>>>  	}

[...]