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authorPaolo Valente <paolo.valente@linaro.org>2020-03-21 10:45:18 +0100
committerJens Axboe <axboe@kernel.dk>2020-03-21 14:30:58 -0600
commitfd1bb3ae54a9a2e0c42709de861c69aa146b8955 (patch)
tree865016ef8439e74c8e2e427ce471adc140950968 /block/bfq-cgroup.c
parent2f95fa5c955d0a9987ffdc3a095e2f4e62c5f2a9 (diff)
downloadlinux-fd1bb3ae54a9a2e0c42709de861c69aa146b8955.tar.bz2
block, bfq: move forward the getting of an extra ref in bfq_bfqq_move
Commit ecedd3d7e199 ("block, bfq: get extra ref to prevent a queue from being freed during a group move") gets an extra reference to a bfq_queue before possibly deactivating it (temporarily), in bfq_bfqq_move(). This prevents the bfq_queue from disappearing before being reactivated in its new group. Yet, the bfq_queue may also be expired (i.e., its service may be stopped) before the bfq_queue is deactivated. And also an expiration may lead to a premature freeing. This commit fixes this issue by simply moving forward the getting of the extra reference already introduced by commit ecedd3d7e199 ("block, bfq: get extra ref to prevent a queue from being freed during a group move"). Reported-by: cki-project@redhat.com Tested-by: cki-project@redhat.com Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bfq-cgroup.c')
-rw-r--r--block/bfq-cgroup.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index f0ff6654af28..9d963ed518d1 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -642,6 +642,12 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
{
struct bfq_entity *entity = &bfqq->entity;
+ /*
+ * Get extra reference to prevent bfqq from being freed in
+ * next possible expire or deactivate.
+ */
+ bfqq->ref++;
+
/* If bfqq is empty, then bfq_bfqq_expire also invokes
* bfq_del_bfqq_busy, thereby removing bfqq and its entity
* from data structures related to current group. Otherwise we
@@ -652,12 +658,6 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
false, BFQQE_PREEMPTED);
- /*
- * get extra reference to prevent bfqq from being freed in
- * next possible deactivate
- */
- bfqq->ref++;
-
if (bfq_bfqq_busy(bfqq))
bfq_deactivate_bfqq(bfqd, bfqq, false, false);
else if (entity->on_st_or_in_serv)
@@ -677,7 +677,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
bfq_schedule_dispatch(bfqd);
- /* release extra ref taken above */
+ /* release extra ref taken above, bfqq may happen to be freed now */
bfq_put_queue(bfqq);
}