On Mon, 2018-05-21 at 17:11 -0600, Keith Busch wrote:
> @@ -650,27 +600,10 @@ static u64 blk_mq_rq_aborted_gstate(struct request *rq)
> void blk_mq_complete_request(struct request *rq)
> {
> struct request_queue *q = rq->q;
> - struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
> - int srcu_idx;
>
> if (unlikely(blk_should_fake_timeout(q)))
> return;
> - [ ... ]
> + __blk_mq_complete_request(rq);
> }
> EXPORT_SYMBOL(blk_mq_complete_request);
> [ ... ]
> static void blk_mq_rq_timed_out(struct request *req, bool reserved)
> {
> const struct blk_mq_ops *ops = req->q->mq_ops;
> enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
>
> - req->rq_flags |= RQF_MQ_TIMEOUT_EXPIRED;
> -
> if (ops->timeout)
> ret = ops->timeout(req, reserved);
>
> switch (ret) {
> case BLK_EH_HANDLED:
> - __blk_mq_complete_request(req);
> - break;
> - case BLK_EH_RESET_TIMER:
> /*
> - * As nothing prevents from completion happening while
> - * ->aborted_gstate is set, this may lead to ignored
> - * completions and further spurious timeouts.
> + * If the request is still in flight, the driver is requesting
> + * blk-mq complete it.
> */
> - blk_mq_rq_update_aborted_gstate(req, 0);
> + if (blk_mq_rq_state(req) == MQ_RQ_IN_FLIGHT)
> + __blk_mq_complete_request(req);
> + break;
> + case BLK_EH_RESET_TIMER:
> blk_add_timer(req);
> break;
> case BLK_EH_NOT_HANDLED:
> @@ -880,64 +782,64 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved)
> }
> }
I think the above changes can lead to concurrent calls of
__blk_mq_complete_request() from the regular completion path and the timeout
path. That's wrong: the __blk_mq_complete_request() caller should guarantee
that no concurrent calls from another context to that function can occur.
Bart.
