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| author | Paolo Valente <paolo.valente@linaro.org> | 2019-01-29 12:06:27 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-01-31 12:50:23 -0700 |
| commit | f3218ad8c6acc9b874060814d6d3ddf154463ac9 (patch) | |
| tree | 6f5be115aed4028905240b168f8d4ab9728c519e /block | |
| parent | 218cb897be6940b8d18eec9bcb32eaa28f1ae8ee (diff) | |
| download | linux-f3218ad8c6acc9b874060814d6d3ddf154463ac9.tar.gz linux-f3218ad8c6acc9b874060814d6d3ddf154463ac9.tar.bz2 linux-f3218ad8c6acc9b874060814d6d3ddf154463ac9.zip | |
block, bfq: make sure queue budgets are not below service received
With some unlucky sequences of events, the function bfq_updated_next_req
updates the current budget of a bfq_queue to a lower value than the
service received by the queue using such a budget. Unfortunately, if
this happens, then the return value of the function bfq_bfqq_budget_left
becomes inconsistent. This commit solves this problem by lower-bounding
the budget computed in bfq_updated_next_req to the service currently
charged to the queue.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 9ea2c4f42501..b0e8006475be 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -907,8 +907,10 @@ static void bfq_updated_next_req(struct bfq_data *bfqd, */ return; - new_budget = max_t(unsigned long, bfqq->max_budget, - bfq_serv_to_charge(next_rq, bfqq)); + new_budget = max_t(unsigned long, + max_t(unsigned long, bfqq->max_budget, + bfq_serv_to_charge(next_rq, bfqq)), + entity->service); if (entity->budget != new_budget) { entity->budget = new_budget; bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", |