Re: [PATCH 1/2] asm-generic/bitops: Add set_bit_release()

[Arnd Bergmann]

On Wed, Oct 21, 2026, at 13:54, Gary Guo wrote:
> On Wed Oct 21, 2026 at 12:33 PM BST, Arnd Bergmann wrote:

>> I'm always confused by this and the new function makes it harder
>> to understand in the current form:
...
>> - Contrary to that, the kerneldoc comment over set_bit() mentions
>>   "This is a relaxed atomic operation (no implied memory barriers)"
>>   and leaves out the kcsan_mb() that is in test_and_set_bit().
>>   This makes the new set_bit_release() sound like a /stronger/
>>   version of set_bit() the same way that test_bit_acquire()
>>   is a stronger version of the (relaxed) test_bit().
>
> set_bit has relaxed semantics while test_and_set_bit implies barrier. RISC-V for
> exmaple will generate the amoor instruction for set_bit, not amoor.aqrl.

Thanks for the clarification, I did misread the implementation
and see how I was confused once more.

     Arnd