On 8/21/19 2:15 AM, Ming Lei wrote:
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, sysfs/debugfs is 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> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- block/blk-mq.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 6968de9d7402..b0ee0cac737f 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2456,11 +2456,6 @@ static void blk_mq_map_swqueue(struct request_queue *q) 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; @@ -2521,8 +2516,6 @@ static void blk_mq_map_swqueue(struct request_queue *q) HCTX_TYPE_DEFAULT, i); }- mutex_unlock(&q->sysfs_lock);- queue_for_each_hw_ctx(q, hctx, i) { /* * If no software queues are mapped to this hardware queue,
How about adding WARN_ON_ONCE(test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags)) ?
Anyway: Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
