blk-mq: prevent unmapped hw queue from being scheduled

When one hardware queue has no mapped software queues, it
shouldn't have been scheduled. Otherwise WARNING or OOPS
can triggered.

blk_mq_hw_queue_mapped() helper is introduce for fixing
the problem.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4854e709aa34..b21a3b6f7b65 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -589,7 +589,7 @@ static void blk_mq_rq_timer(unsigned long priv)
                  * If not software queues are currently mapped to this
                  * hardware queue, there's nothing to check
                  */
-                if (!hctx->nr_ctx || !hctx->tags)
+                if (!blk_mq_hw_queue_mapped(hctx))
                         continue;
 
                 blk_mq_tag_busy_iter(hctx, blk_mq_check_expired, &data);
@@ -809,7 +809,8 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 
 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 {
-        if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
+        if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
+            !blk_mq_hw_queue_mapped(hctx)))
                 return;
 
         if (!async) {
@@ -916,6 +917,9 @@ static void blk_mq_delay_work_fn(struct work_struct *work)
 
 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 {
+        if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
+                return;
+
         kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
                         &hctx->delay_work, msecs_to_jiffies(msecs));
 }
diff --git a/block/blk-mq.h b/block/blk-mq.h
index d567d5283ffa..206230e64f79 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -115,4 +115,9 @@ static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,
         data->hctx = hctx;
 }
 
+static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
+{
+        return hctx->nr_ctx && hctx->tags;
+}
+
 #endif