diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq-sysfs.c | 6 | ||||
| -rw-r--r-- | block/blk-mq.c | 18 | ||||
| -rw-r--r-- | block/blk-sysfs.c | 11 |
3 files changed, 22 insertions, 13 deletions
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index ed5217867555..371d8800b48a 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -402,6 +402,12 @@ static void blk_mq_sysfs_init(struct request_queue *q) } } +/* see blk_register_queue() */ +void blk_mq_finish_init(struct request_queue *q) +{ + percpu_ref_switch_to_percpu(&q->mq_usage_counter); +} + int blk_mq_register_disk(struct gendisk *disk) { struct device *dev = disk_to_dev(disk); diff --git a/block/blk-mq.c b/block/blk-mq.c index df8e1e09dd17..38f4a165640d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -119,16 +119,7 @@ void blk_mq_freeze_queue(struct request_queue *q) spin_unlock_irq(q->queue_lock); if (freeze) { - /* - * XXX: Temporary kludge to work around SCSI blk-mq stall. - * SCSI synchronously creates and destroys many queues - * back-to-back during probe leading to lengthy stalls. - * This will be fixed by keeping ->mq_usage_counter in - * atomic mode until genhd registration, but, for now, - * let's work around using expedited synchronization. - */ - __percpu_ref_kill_expedited(&q->mq_usage_counter); - + percpu_ref_kill(&q->mq_usage_counter); blk_mq_run_queues(q, false); } wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter)); @@ -1804,7 +1795,12 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set) if (!q) goto err_hctxs; - if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release)) + /* + * Init percpu_ref in atomic mode so that it's faster to shutdown. + * See blk_register_queue() for details. + */ + if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release, + PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) goto err_map; setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q); diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 17f5c84ce7bf..521ae9089c50 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -551,12 +551,19 @@ int blk_register_queue(struct gendisk *disk) return -ENXIO; /* - * Initialization must be complete by now. Finish the initial - * bypass from queue allocation. + * SCSI probing may synchronously create and destroy a lot of + * request_queues for non-existent devices. Shutting down a fully + * functional queue takes measureable wallclock time as RCU grace + * periods are involved. To avoid excessive latency in these + * cases, a request_queue starts out in a degraded mode which is + * faster to shut down and is made fully functional here as + * request_queues for non-existent devices never get registered. */ if (!blk_queue_init_done(q)) { queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q); blk_queue_bypass_end(q); + if (q->mq_ops) + blk_mq_finish_init(q); } ret = blk_trace_init_sysfs(dev); |