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

[Bart Van Assche]

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.