malhuda/msm-4.14
1
0
Fork 0
mirror of https://github.com/rd-stuffs/msm-4.14.git synced 2025-02-20 11:45:48 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

blk-mq: put the driver tag of nxt rq before first one is requeued

Browse Source 
When freeing the driver tag of the next rq with an I/O scheduler
configured, we get the first entry of the list. However, this can
race with requeue of a request, and we end up getting the wrong request
from the head of the list. Free the driver tag of next rq before the
failed one is requeued in the failure branch of queue_rq callback.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: azrim <mirzaspc@gmail.com>
This commit is contained in:
Jianchao Wang 2017-11-02 23:24:32 +08:00 committed by azrim
parent 38ab7108e1
commit 5e518b7dcf
No known key found for this signature in database
GPG Key ID: 497F8FB059B45D1C
1 changed files with 9 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
block/blk-mq.c
View File

@ -1072,7 +1072,7 @@ static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
{
struct blk_mq_hw_ctx *hctx;
struct request *rq;
struct request *rq, *nxt;
int errors, queued;
if (list_empty(list))
@ -1118,14 +1118,20 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
if (list_empty(list))
bd.last = true;
else {
struct request *nxt;
nxt = list_first_entry(list, struct request, queuelist);
bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
}
ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_STS_RESOURCE) {
/*
* If an I/O scheduler has been configured and we got a
* driver tag for the next request already, free it again.
*/
if (!list_empty(list)) {
nxt = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(nxt);
}
blk_mq_put_driver_tag_hctx(hctx, rq);
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
@ -1148,13 +1154,6 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
* that is where we will continue on next queue run.
*/
if (!list_empty(list)) {
/*
* If an I/O scheduler has been configured and we got a driver
* tag for the next request already, free it again.
*/
rq = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(rq);
spin_lock(&hctx->lock);
list_splice_init(list, &hctx->dispatch);
spin_unlock(&hctx->lock);