| Message ID | 20200728132951.29459-1-dwagner@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Use non _rcu version of list functions for tag_set_list | expand |
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 <ming.lei@redhat.com> > Signed-off-by: Daniel Wagner <dwagner@suse.de> > --- > 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 <hare@suse.de> Cheers, Hannes
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.
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); }
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 <ming.lei@redhat.com> Signed-off-by: Daniel Wagner <dwagner@suse.de> --- block/blk-mq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)