Re: [PATCH] buffer: Avoid setting buffer bits that are already set

[Andi Kleen]

kemi <kemi.wang@xxxxxxxxx> writes:
>
> I'll see if I can find some
>> time to implement the above in a nice way.
>
> Agree. Maybe something like test_and_set_bit() would be more suitable.

test_and_set_bit is a very different operation for the CPU because
it is atomic for both. But we want the initial read to not
be atomic.

If you add special functions use a different variant that is only
atomic for the set.

-Andi