Re: [PATCH 3/3] sched: Add cond_resched_rwlock

[Paolo Bonzini <pbonzini@redhat.com>]

On 27/10/20 19:44, Peter Zijlstra wrote:
> On Tue, Oct 27, 2020 at 09:49:50AM -0700, Ben Gardon wrote:
> 
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index d2003a7d5ab55..ac58e7829a063 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -6152,6 +6152,46 @@ int __cond_resched_lock(spinlock_t *lock)
>>  }
>>  EXPORT_SYMBOL(__cond_resched_lock);
>>  
>> +int __cond_resched_rwlock_read(rwlock_t *lock)
>> +{
>> +	int resched = should_resched(PREEMPT_LOCK_OFFSET);
>> +	int ret = 0;
>> +
>> +	lockdep_assert_held(lock);
> 
> 	lockdep_assert_held_read(lock);
> 
>> +
>> +	if (rwlock_needbreak(lock) || resched) {
>> +		read_unlock(lock);
>> +		if (resched)
>> +			preempt_schedule_common();
>> +		else
>> +			cpu_relax();
>> +		ret = 1;
>> +		read_lock(lock);
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(__cond_resched_rwlock_read);
>> +
>> +int __cond_resched_rwlock_write(rwlock_t *lock)
>> +{
>> +	int resched = should_resched(PREEMPT_LOCK_OFFSET);
>> +	int ret = 0;
>> +
>> +	lockdep_assert_held(lock);
> 
> 	lockdep_assert_held_write(lock);
> 
>> +
>> +	if (rwlock_needbreak(lock) || resched) {
>> +		write_unlock(lock);
>> +		if (resched)
>> +			preempt_schedule_common();
>> +		else
>> +			cpu_relax();
>> +		ret = 1;
>> +		write_lock(lock);
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(__cond_resched_rwlock_write);
> 
> If this is the only feedback (the patches look fine to me), don't bother
> resending, I'll edit them when applying.
> 

If that is an Acked-by, I'll merge them through the KVM tree when time
comes.

Paolo