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block, bfq: get a ref to a group when adding it to a service tree

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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>
This commit is contained in:
Paolo Valente 2020-02-03 11:40:59 +01:00 committed by Jens Axboe
parent 4d8340d0d4
commit db37a34c56
3 changed files with 12 additions and 3 deletions
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2
block/bfq-cgroup.c
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@ -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);

1
block/bfq-iosched.h
View File

@ -985,6 +985,7 @@ 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

12
block/bfq-wf2q.c
View File

@ -533,7 +533,9 @@ 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));
}
/**
@ -647,8 +649,14 @@ 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);
else
bfqg_and_blkg_put(container_of(entity, struct bfq_group,
entity));
}
/**