redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

blk-mq: don't hold q->sysfs_lock in blk_mq_map_swqueue 

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 2f8f1336a4 ("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@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
alistair/sunxi64-5.4-dsi
Ming Lei 2019-08-27 19:01:46 +08:00 committed by Jens Axboe
parent c48dac137a
commit c6ba933358
1 changed files with 0 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
block/blk-mq.c
View File

@ -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,