On Thu, 2018-12-20 at 15:50 -0700, Jens Axboe wrote:
> +static void blk_fq_rcu_free(struct work_struct *work)
> +{
> + struct blk_flush_queue *fq = container_of(to_rcu_work(work),
> + struct blk_flush_queue,
> + rcu_work);
> +
> + kfree(fq->flush_rq);
> + kfree(fq);
> +}
> +
> void blk_free_flush_queue(struct blk_flush_queue *fq)
> {
> /* bio based request queue hasn't flush queue */
> if (!fq)
> return;
>
> - kfree(fq->flush_rq);
> - kfree(fq);
> + INIT_RCU_WORK(&fq->rcu_work, blk_fq_rcu_free);
> + queue_rcu_work(system_wq, &fq->rcu_work);
> }
Can INIT_RCU_WORK() + queue_rcu_work() be changed into call_rcu()? The latter
namely uses a smaller data structure.
> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
> index 2089c6c62f44..c39b58391ae8 100644
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -228,13 +228,15 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned
> int bitnr, void *data)
>
> if (!reserved)
> bitnr += tags->nr_reserved_tags;
> - rq = tags->rqs[bitnr];
> + if (tags->rqs[bitnr].queue != hctx->queue)
> + return true;
Since blk_mq_tag_set_rq() is not serialized against this function I doubt that
the tags->rqs[bitnr].queue != hctx->queue check helps. Can it be left out?
> +struct rq_tag_entry {
> + struct request_queue *queue;
> + struct request *rq;
If the new test can be left out from bt_iter(), can this new data structure be
left out too? In other words, keep the existing approach of only storing the
request pointer and not the queue pointer.
Thanks,
Bart.
