[PATCH BUGFIX 5/6] block, bfq: get a ref to a group when adding it to a service tree
From: Paolo Valente <hidden>
Date: 2020-01-31 09:25:16
Also in:
lkml
Subsystem:
bfq i/o scheduler, block layer, control group - block io controller (blkio), the rest · Maintainers:
Yu Kuai, Jens Axboe, Tejun Heo, Josef Bacik, Linus Torvalds
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: Chris Evich <redacted> Signed-off-by: Paolo Valente <redacted> --- block/bfq-cgroup.c | 2 +- block/bfq-iosched.h | 1 + block/bfq-wf2q.c | 16 +++++++++++++++- 3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index c818c64766e5..f85b25fd06f2 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 f1cb89def7f8..b9627ec7007b 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 26776bdbdf36..ef06e0d34b5b 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c@@ -533,7 +533,13 @@ static void bfq_get_entity(struct bfq_entity *entity) bfqq->ref++; bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", bfqq, bfqq->ref); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + } else + bfqg_and_blkg_get(container_of(entity, struct bfq_group, + entity)); +#else } +#endif } /**
@@ -647,8 +653,16 @@ static void bfq_forget_entity(struct bfq_service_tree *st, entity->on_st_or_in_serv = false; st->wsum -= entity->weight; - if (bfqq && !is_in_service) + if (is_in_service) + return; + + if (bfqq) bfq_put_queue(bfqq); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + else + bfqg_and_blkg_put(container_of(entity, struct bfq_group, + entity)); +#endif } /**
--
2.20.1