[PATCH 5.4 001/168] block, bfq: get a ref to a group when adding it to a service tree
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STALE2423d
REVIEWED: 2 (0M)
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2020-03-10 13:33:34
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
Status: Reviewed.
2 review trailers.
From: Paolo Valente <redacted> [ 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 <redacted> Tested-by: Chris Evich <redacted> Signed-off-by: Paolo Valente <redacted> 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 86a607cf19a10..0999d56bc4d19 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 5d1a519640f6a..e0e4a413d43a5 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h@@ -978,6 +978,7 @@ 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)); } /**
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2.20.1