From: Paolo Valente paolo.valente@linaro.org
[ Upstream commit db37a34c563bf4692b36990ae89005c031385e52 ]
BFQ schedules generic entities, which may represent either bfq_queues or groups of bfq_queues. When an entity is inserted into a service tree, a reference must be taken, to make sure that the entity does not disappear while still referred in the tree. Unfortunately, such a reference is mistakenly taken only if the entity represents a bfq_queue. This commit takes a reference also in case the entity represents a group.
Tested-by: Oleksandr Natalenko oleksandr@natalenko.name Tested-by: Chris Evich cevich@redhat.com Signed-off-by: Paolo Valente paolo.valente@linaro.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/bfq-cgroup.c | 2 +- block/bfq-iosched.h | 1 + block/bfq-wf2q.c | 12 ++++++++++-- 3 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index e1419edde2ec5..e7919e76a27c2 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -332,7 +332,7 @@ static void bfqg_put(struct bfq_group *bfqg) kfree(bfqg); }
-static void bfqg_and_blkg_get(struct bfq_group *bfqg) +void bfqg_and_blkg_get(struct bfq_group *bfqg) { /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */ bfqg_get(bfqg); diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index 8526f20c53bc1..144bc544be568 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -984,6 +984,7 @@ struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); struct bfq_group *bfqq_group(struct bfq_queue *bfqq); struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node); +void bfqg_and_blkg_get(struct bfq_group *bfqg); void bfqg_and_blkg_put(struct bfq_group *bfqg);
#ifdef CONFIG_BFQ_GROUP_IOSCHED diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index 05f0bf4a1144d..44079147e396e 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -536,7 +536,9 @@ static void bfq_get_entity(struct bfq_entity *entity) bfqq->ref++; bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", bfqq, bfqq->ref); - } + } else + bfqg_and_blkg_get(container_of(entity, struct bfq_group, + entity)); }
/** @@ -650,8 +652,14 @@ static void bfq_forget_entity(struct bfq_service_tree *st,
entity->on_st = false; st->wsum -= entity->weight; - if (bfqq && !is_in_service) + if (is_in_service) + return; + + if (bfqq) bfq_put_queue(bfqq); + else + bfqg_and_blkg_put(container_of(entity, struct bfq_group, + entity)); }
/**