On 12/01/2022 12:30, Andy Shevchenko wrote:
+ if (test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags) ||
+ test_and_set_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags)) {
Whoever wrote this code did too much defensive programming, because the first
conditional doesn't make much sense here. Am I right?
I think because this judgement is in the general IO process, there are also
some performance considerations here.
I didn't buy this. Is there any better argument why you need redundant
test_bit() call?
I think that the idea is that test_bit() is fast and test_and_set_bit()
is slow; as such, if we generally expect the bit to be set, then there
is no need to do the slower test_and_set_bit() always.
