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-rw-r--r--block/blk-mq.h15
1 files changed, 14 insertions, 1 deletions
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 3bd43b10032f..89a20fffa4b1 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -155,7 +155,7 @@ struct blk_mq_alloc_data {
/* allocate multiple requests/tags in one go */
unsigned int nr_tags;
- struct request **cached_rq;
+ struct rq_list *cached_rqs;
/* input & output parameter */
struct blk_mq_ctx *ctx;
@@ -230,6 +230,19 @@ static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data
static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
{
+ /* Fast path: hardware queue is not stopped most of the time. */
+ if (likely(!test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
+ return false;
+
+ /*
+ * This barrier is used to order adding of dispatch list before and
+ * the test of BLK_MQ_S_STOPPED below. Pairs with the memory barrier
+ * in blk_mq_start_stopped_hw_queue() so that dispatch code could
+ * either see BLK_MQ_S_STOPPED is cleared or dispatch list is not
+ * empty to avoid missing dispatching requests.
+ */
+ smp_mb();
+
return test_bit(BLK_MQ_S_STOPPED, &hctx->state);
}