The only difference between ->run_work and ->delay_work, is that the latter is used to defer running a queue. This is done by marking the queue stopped, and scheduling ->delay_work to run sometime in the future. While the queue is stopped, direct runs or runs through ->run_work will not run the queue.
If we combine the handlers, then we need to handle two things: 1) If a delayed/stopped run is scheduled, then we should not run the queue before that has been completed. 2) If a queue is delayed/stopped, the handler needs to restart the queue. Normally a run of a queue with the stopped bit set would be a no-op. Case 1 is handled by modifying a currently pending queue run to the deadline set by the caller of blk_mq_delay_queue(). Subsequent attempts to queue a queue run will find the work item already pending, and direct runs will see a stopped queue as before. Case 2 is handled by adding a new bit, BLK_MQ_S_START_ON_RUN, that tells the work handler that it should clear a stopped queue and run the handler. Signed-off-by: Jens Axboe <[email protected]> --- block/blk-core.c | 4 +--- block/blk-mq.c | 34 ++++++++++++++++++++++------------ include/linux/blk-mq.h | 3 +-- 3 files changed, 24 insertions(+), 17 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index bffb8640346b..4f0104afa848 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -268,10 +268,8 @@ void blk_sync_queue(struct request_queue *q) struct blk_mq_hw_ctx *hctx; int i; - queue_for_each_hw_ctx(q, hctx, i) { + queue_for_each_hw_ctx(q, hctx, i) cancel_delayed_work_sync(&hctx->run_work); - cancel_delayed_work_sync(&hctx->delay_work); - } } else { cancel_delayed_work_sync(&q->delay_work); } diff --git a/block/blk-mq.c b/block/blk-mq.c index 7afba6ab5a96..e97ed8e7f359 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1223,7 +1223,6 @@ EXPORT_SYMBOL(blk_mq_queue_stopped); void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx) { cancel_delayed_work(&hctx->run_work); - cancel_delayed_work(&hctx->delay_work); set_bit(BLK_MQ_S_STOPPED, &hctx->state); } EXPORT_SYMBOL(blk_mq_stop_hw_queue); @@ -1281,27 +1280,39 @@ static void blk_mq_run_work_fn(struct work_struct *work) struct blk_mq_hw_ctx *hctx; hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work); - __blk_mq_run_hw_queue(hctx); -} -static void blk_mq_delay_work_fn(struct work_struct *work) -{ - struct blk_mq_hw_ctx *hctx; + /* + * If we are stopped, don't run the queue. The exception is if + * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear + * the STOPPED bit and run it. + */ + if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) { + if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state)) + return; - hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work); + clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state); + clear_bit(BLK_MQ_S_STOPPED, &hctx->state); + } - if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state)) - __blk_mq_run_hw_queue(hctx); + __blk_mq_run_hw_queue(hctx); } + void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs) { if (unlikely(!blk_mq_hw_queue_mapped(hctx))) return; + /* + * Stop the hw queue, then modify currently delayed work. + * This should prevent us from running the queue prematurely. + * Mark the queue as auto-clearing STOPPED when it runs. + */ blk_mq_stop_hw_queue(hctx); - kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx), - &hctx->delay_work, msecs_to_jiffies(msecs)); + set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state); + kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), + &hctx->run_work, + msecs_to_jiffies(msecs)); } EXPORT_SYMBOL(blk_mq_delay_queue); @@ -1886,7 +1897,6 @@ static int blk_mq_init_hctx(struct request_queue *q, node = hctx->numa_node = set->numa_node; INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn); - INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn); spin_lock_init(&hctx->lock); INIT_LIST_HEAD(&hctx->dispatch); hctx->queue = q; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 2b4573a9ccf4..7a114b7b943c 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -51,8 +51,6 @@ struct blk_mq_hw_ctx { atomic_t nr_active; - struct delayed_work delay_work; - struct hlist_node cpuhp_dead; struct kobject kobj; @@ -160,6 +158,7 @@ enum { BLK_MQ_S_TAG_ACTIVE = 1, BLK_MQ_S_SCHED_RESTART = 2, BLK_MQ_S_TAG_WAITING = 3, + BLK_MQ_S_START_ON_RUN = 4, BLK_MQ_MAX_DEPTH = 10240, -- 2.7.4
