On Sun, 2017-11-05 at 15:38 +0000, Bart Van Assche wrote: > On Sun, 2017-11-05 at 20:10 +0800, Ming Lei wrote: > > diff --git a/block/blk-core.c b/block/blk-core.c > > index 048be4aa6024..0b121f29e3b1 100644 > > --- a/block/blk-core.c > > +++ b/block/blk-core.c > > @@ -658,6 +658,10 @@ void blk_cleanup_queue(struct request_queue *q) > > queue_flag_set(QUEUE_FLAG_DEAD, q); > > spin_unlock_irq(lock); > > > > + /* respect queue DEAD via quiesce for blk-mq */ > > + if (q->mq_ops) > > + blk_mq_quiesce_queue(q); > > + > > /* for synchronous bio-based driver finish in-flight integrity i/o */ > > blk_flush_integrity(); > > Have you considered to change the blk_freeze_queue_start() call in > blk_set_queue_dying() into a blk_freeze_queue() call? That approach has the > advantage that no new if (q->mq_ops) test has to be introduced.
There is an additional reason why I think it would be better to make blk_set_queue_dying() wait until requests that are in progress have finished. Some block drivers, e.g. the mtip driver, start cleaning up resources immediately after blk_set_queue_dying() has returned. So making blk_set_queue_dying() wait would fix a race condition in at least the mtip driver. Bart.
