Re: [PATCH] blk-mq: clear stale inactive flag on hctx reuse

[Bart Van Assche <bvanassche@acm.org>]

On 10/20/26 7:39 AM, Jens Axboe wrote:
> On 10/20/26 8:13 AM, Bart Van Assche wrote:
>> On 10/20/26 5:51 AM, Nirmoy Das wrote:
>>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>>> index 025a799f35b924d..00b75eb95dd943a 100644
>>> --- a/block/blk-mq.c
>>> +++ b/block/blk-mq.c
>>> @@ -4002,6 +4002,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
>>>            goto fail;
>>>          hctx->queue_num = hctx_idx;
>>> +    clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
>>>          hctx->tags = set->tags[hctx_idx];
>>
>> Why clear_bit() instead of __clear_bit()?
> 
> Since this isn't a hot path at all, going into details like
> that does more harm than good. clear_bit() is totally fine
> and honestly preferred.

Although I'm fine with the patch as-is, I want to clarify that
the concern behind my reply is code readability rather than a
micro-optimization. No other context should be accessing a hctx while
blk_mq_init_hctx() is in progress. Using clear_bit() instead of
__clear_bit() might make readers of this code wonder whether any other
context might be accessing the hctx concurrently with the
blk_mq_init_hctx() call.

Thanks,

Bart.