2019-10-15 15:52:13

by Tejun Heo

Subject: [PATCH block/for-linus] blk-rq-qos: fix first node deletion of rq_qos_del()

rq_qos_del() incorrectly assigns the node being deleted to the head if
it was the first on the list in the !prev path. Fix it by iterating
with ** instead.

Signed-off-by: Tejun Heo <[email protected]>
Cc: Josef Bacik <[email protected]>
Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
Cc: [email protected] # v4.19+
---
block/blk-rq-qos.h | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -108,16 +108,13 @@ static inline void rq_qos_add(struct req

static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
{
- struct rq_qos *cur, *prev = NULL;
- for (cur = q->rq_qos; cur; cur = cur->next) {
- if (cur == rqos) {
- if (prev)
- prev->next = rqos->next;
- else
- q->rq_qos = cur;
+ struct rq_qos **cur;
+
+ for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) {
+ if (*cur == rqos) {
+ *cur = rqos->next;
break;
}
- prev = cur;
}

blk_mq_debugfs_unregister_rqos(rqos);

2019-10-15 20:02:41

by Jens Axboe

Subject: Re: [PATCH block/for-linus] blk-rq-qos: fix first node deletion of rq_qos_del()

On 10/15/19 9:49 AM, Tejun Heo wrote:
> rq_qos_del() incorrectly assigns the node being deleted to the head if
> it was the first on the list in the !prev path. Fix it by iterating
> with ** instead.

Well, that's unfortunate... Applied.

--
Jens Axboe