mmc: block: Fix unsupported parallel dispatch of requests
The mmc block driver does not support parallel dispatch of requests. In
normal circumstances, all requests are anyway funneled through a single
work item, so parallel dispatch never happens. However it can happen if
there is no elevator.
Fix that by detecting if a dispatch is in progress and returning busy
(BLK_STS_RESOURCE) in that case
Fixes: 81196976ed94 ("mmc: block: Add blk-mq support")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 648eb67..6edffee 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -238,10 +238,6 @@ static void mmc_mq_exit_request(struct blk_mq_tag_set *set, struct request *req,
mmc_exit_request(mq->queue, req);
}
-/*
- * We use BLK_MQ_F_BLOCKING and have only 1 hardware queue, which means requests
- * will not be dispatched in parallel.
- */
static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
@@ -264,7 +260,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_lock_irq(q->queue_lock);
- if (mq->recovery_needed) {
+ if (mq->recovery_needed || mq->busy) {
spin_unlock_irq(q->queue_lock);
return BLK_STS_RESOURCE;
}
@@ -291,6 +287,9 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
break;
}
+ /* Parallel dispatch of requests is not supported at the moment */
+ mq->busy = true;
+
mq->in_flight[issue_type] += 1;
get_card = (mmc_tot_in_flight(mq) == 1);
cqe_retune_ok = (mmc_cqe_qcnt(mq) == 1);
@@ -333,9 +332,12 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
mq->in_flight[issue_type] -= 1;
if (mmc_tot_in_flight(mq) == 0)
put_card = true;
+ mq->busy = false;
spin_unlock_irq(q->queue_lock);
if (put_card)
mmc_put_card(card, &mq->ctx);
+ } else {
+ WRITE_ONCE(mq->busy, false);
}
return ret;