diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq.c | 6 | ||||
| -rw-r--r-- | block/blk-mq.h | 13 |
2 files changed, 19 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 0cb559d63998..0f20320053d1 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1544,6 +1544,12 @@ void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) return; clear_bit(BLK_MQ_S_STOPPED, &hctx->state); + /* + * Pairs with the smp_mb() in blk_mq_hctx_stopped() to order the + * clearing of BLK_MQ_S_STOPPED above and the checking of dispatch + * list in the subsequent routine. + */ + smp_mb__after_atomic(); blk_mq_run_hw_queue(hctx, async); } EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue); diff --git a/block/blk-mq.h b/block/blk-mq.h index 5ad9251627f8..0973b8006234 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -142,6 +142,19 @@ 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); } |