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| author | Paolo Valente <paolo.valente@linaro.org> | 2020-02-03 11:40:56 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-02-03 06:58:15 -0700 |
| commit | ecedd3d7e19911ab8fe42f17b77c0a30fe7f4db3 (patch) | |
| tree | 604e9e103322c6b4708d9fcf8ecd2e24be6c92e8 /block/bfq-cgroup.c | |
| parent | 32c59e3a9a5a0b180dd015755d6d18ca31e55935 (diff) | |
| download | lwn-ecedd3d7e19911ab8fe42f17b77c0a30fe7f4db3.tar.gz lwn-ecedd3d7e19911ab8fe42f17b77c0a30fe7f4db3.zip | |
block, bfq: get extra ref to prevent a queue from being freed during a group move
In bfq_bfqq_move(), the bfq_queue, say Q, to be moved to a new group
may happen to be deactivated in the scheduling data structures of the
source group (and then activated in the destination group). If Q is
referred only by the data structures in the source group when the
deactivation happens, then Q is freed upon the deactivation.
This commit addresses this issue by getting an extra reference before
the possible deactivation, and releasing this extra reference after Q
has been moved.
Tested-by: Chris Evich <cevich@redhat.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
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.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index e1419edde2ec..8ab7f18ff8cb 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -651,6 +651,12 @@ 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) @@ -670,6 +676,8 @@ 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 */ + bfq_put_queue(bfqq); } /** |