Re: [RFC][PATCH 23/24] atomic: Collapse all atomic_{set,clear}_mask definitions

Chris Metcalf
2015-07-10T13:34:14Z

On 7/10/2015 6:39 AM, Peter Zijlstra wrote:
> On Fri, Jul 10, 2015 at 11:10:33AM +0200, Geert Uytterhoeven wrote:
>> Hi Peter,
>>
>> On Thu, Jul 9, 2015 at 7:29 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>>> --- a/include/linux/atomic.h
>>> +++ b/include/linux/atomic.h
>>> @@ -28,6 +28,23 @@ static inline int atomic_add_unless(atom
>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>>> #endif
>>>
>>> +#ifndef atomic_nand
>>> +static inline void atomic_nand(int i, atomic_t *v)
>>> +{
>>> + atomic_and(~i, v);
>> That sounds like a misnomer...
>>
>> Your NAND is "A & ~B", while my[*] NAND is "~(A & B)"?
>>
>> [*] https://en.wikipedia.org/wiki/NAND_logic
> Right you are.
>
>> What about atomic_clear()? (Is atomic_bic() too ARM-centric?)
> atomic_and_not() ?

I've seen this as ANDN (as opposed to NAND). That's the name I used in
the tilepro atomics as the thing that implements the bitmask clear operation.
SPARC also has an "andn" instruction with this semantics.

--
Chris Metcalf, EZChip Semiconductor