tag_set_list is only accessed under the tag_set_lock lock. There is
no need for using the _rcu list functions.
The _rcu list function were introduced to allow read access to the
tag_set_list protected under RCU, see 705cda97ee3a ("blk-mq: Make it
safe to use RCU to iterate over blk_mq_tag_set.tag_list") and
05b79413946d ("Revert "blk-mq: don't handle TAG_SHARED in restart"").
Those changes got reverted later but the cleanup commit missed a
couple of places to undo the changes.
Fixes: 97889f9ac24f ("blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()"
Cc: Ming Lei <[email protected]>
Signed-off-by: Daniel Wagner <[email protected]>
---
block/blk-mq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e32cb0217135..14ee7506f32f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2792,7 +2792,7 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&set->tag_list_lock);
- list_del_rcu(&q->tag_set_list);
+ list_del(&q->tag_set_list);
if (list_is_singular(&set->tag_list)) {
/* just transitioned to unshared */
set->flags &= ~BLK_MQ_F_TAG_SHARED;
@@ -2819,7 +2819,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
}
if (set->flags & BLK_MQ_F_TAG_SHARED)
queue_set_hctx_shared(q, true);
- list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
+ list_add_tail(&q->tag_set_list, &set->tag_list);
mutex_unlock(&set->tag_list_lock);
}
--
2.16.4
On 7/28/20 3:29 PM, Daniel Wagner wrote:
> tag_set_list is only accessed under the tag_set_lock lock. There is
> no need for using the _rcu list functions.
>
> The _rcu list function were introduced to allow read access to the
> tag_set_list protected under RCU, see 705cda97ee3a ("blk-mq: Make it
> safe to use RCU to iterate over blk_mq_tag_set.tag_list") and
> 05b79413946d ("Revert "blk-mq: don't handle TAG_SHARED in restart"").
> Those changes got reverted later but the cleanup commit missed a
> couple of places to undo the changes.
>
> Fixes: 97889f9ac24f ("blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()"
> Cc: Ming Lei <[email protected]>
> Signed-off-by: Daniel Wagner <[email protected]>
> ---
> block/blk-mq.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index e32cb0217135..14ee7506f32f 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2792,7 +2792,7 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
> struct blk_mq_tag_set *set = q->tag_set;
>
> mutex_lock(&set->tag_list_lock);
> - list_del_rcu(&q->tag_set_list);
> + list_del(&q->tag_set_list);
> if (list_is_singular(&set->tag_list)) {
> /* just transitioned to unshared */
> set->flags &= ~BLK_MQ_F_TAG_SHARED;
> @@ -2819,7 +2819,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
> }
> if (set->flags & BLK_MQ_F_TAG_SHARED)
> queue_set_hctx_shared(q, true);
> - list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
> + list_add_tail(&q->tag_set_list, &set->tag_list);
>
> mutex_unlock(&set->tag_list_lock);
> }
>
Indeed.
Reviewed-by: Hannes Reinecke <[email protected]>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
[email protected] +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
On 7/28/20 7:29 AM, Daniel Wagner wrote:
> tag_set_list is only accessed under the tag_set_lock lock. There is
> no need for using the _rcu list functions.
>
> The _rcu list function were introduced to allow read access to the
> tag_set_list protected under RCU, see 705cda97ee3a ("blk-mq: Make it
> safe to use RCU to iterate over blk_mq_tag_set.tag_list") and
> 05b79413946d ("Revert "blk-mq: don't handle TAG_SHARED in restart"").
> Those changes got reverted later but the cleanup commit missed a
> couple of places to undo the changes.
Applied, thanks.
--
Jens Axboe