From: Ming Lei <ming.lei@xxxxxxxxxx>
commit c6ba933358f0d7a6a042b894dba20cc70396a6d3 upstream.
blk_mq_map_swqueue() is called from blk_mq_init_allocated_queue()
and blk_mq_update_nr_hw_queues(). For the former caller, the kobject
isn't exposed to userspace yet. For the latter caller, hctx sysfs entries
and debugfs are un-registered before updating nr_hw_queues.
On the other hand, commit 2f8f1336a48b ("blk-mq: always free hctx after
request queue is freed") moves freeing hctx into queue's release
handler, so there won't be race with queue release path too.
So don't hold q->sysfs_lock in blk_mq_map_swqueue().
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-mq.c | 7 -------
1 file changed, 7 deletions(-)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2324,11 +2324,6 @@ static void blk_mq_map_swqueue(struct re
struct blk_mq_ctx *ctx;
struct blk_mq_tag_set *set = q->tag_set;
- /*
- * Avoid others reading imcomplete hctx->cpumask through sysfs
- */
- mutex_lock(&q->sysfs_lock);
-
queue_for_each_hw_ctx(q, hctx, i) {
cpumask_clear(hctx->cpumask);
hctx->nr_ctx = 0;
@@ -2362,8 +2357,6 @@ static void blk_mq_map_swqueue(struct re
hctx->ctxs[hctx->nr_ctx++] = ctx;
}
- mutex_unlock(&q->sysfs_lock);
-
queue_for_each_hw_ctx(q, hctx, i) {
/*
* If no software queues are mapped to this hardware queue,
