Re: [PATCH 1/2] percpu_ref: add percpu_ref_atomic_count()

[Jens Axboe <axboe@kernel.dk>]

On 4/16/21 9:31 AM, Bart Van Assche wrote:
> On 4/15/21 5:22 PM, Pavel Begunkov wrote:
>> diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
>> index a1071cdefb5a..56286995e2b8 100644
>> --- a/lib/percpu-refcount.c
>> +++ b/lib/percpu-refcount.c
>> @@ -425,6 +425,32 @@ bool percpu_ref_is_zero(struct percpu_ref *ref)
>>  }
>>  EXPORT_SYMBOL_GPL(percpu_ref_is_zero);
>>  
>> +/**
>> + * percpu_ref_atomic_count - returns number of left references
>> + * @ref: percpu_ref to test
>> + *
>> + * This function is safe to call as long as @ref is switch into atomic mode,
>> + * and is between init and exit.
>> + */
> 
> How about using the name percpu_ref_read() instead of
> percpu_ref_atomic_count()?

Not sure we're going that route, but in any case, I think it's important
to have it visibly require the ref to be in atomic mode. Maybe
percpu_ref_read_atomic() would be better, but I do think 'atomic' has
to be in the name.

-- 
Jens Axboe