[PATCH V2 2/2] block: mark queue init done at the end of blk_register_queue
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STALE1955d
SUPERSEDED
From: Ming Lei <hidden>
Date: 2021-06-08 07:19:44
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Revision v2 of 3 in this series.
Revisions (3)
- v1 [diff vs current]
- v2 current
- v3 [diff vs current]
Mark queue init done when everything is done well in blk_register_queue(), so that wbt_enable_default() can be run quickly without any RCU period involved since adding rq qos requires to freeze queue. Also no any side effect by delaying to mark queue init done. Reported-by: Yi Zhang <redacted> Cc: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <redacted> --- block/blk-sysfs.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index f89e2fc3963b..370d83c18057 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c@@ -866,20 +866,6 @@ int blk_register_queue(struct gendisk *disk) "%s is registering an already registered queue\n", kobject_name(&dev->kobj)); - /* - * 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)) { - blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q); - percpu_ref_switch_to_percpu(&q->q_usage_counter); - } - blk_queue_update_readahead(q); ret = blk_trace_init_sysfs(dev);
@@ -938,6 +924,21 @@ int blk_register_queue(struct gendisk *disk) ret = 0; unlock: mutex_unlock(&q->sysfs_dir_lock); + + /* + * 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)) { + blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q); + percpu_ref_switch_to_percpu(&q->q_usage_counter); + } + return ret; } EXPORT_SYMBOL_GPL(blk_register_queue);
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2.31.1