[PATCH V9 09/11] blk-mq: add blk_mq_hctx_handle_dead_cpu for handling cpu dead

[Ming Lei <ming.lei@xxxxxxxxxx>]

Add helper of blk_mq_hctx_handle_dead_cpu for handling cpu dead,
and prepare for handling inactive hctx.

No functional change.

Cc: John Garry <john.garry@xxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/blk-mq.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4a2250ac4fbb..73e1a1d4c1c5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2382,22 +2382,13 @@ static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
 	return 0;
 }
 
-/*
- * 'cpu' is going away. splice any existing rq_list entries from this
- * software queue to the hw queue dispatch list, and ensure that it
- * gets run.
- */
-static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
+static void blk_mq_hctx_handle_dead_cpu(struct blk_mq_hw_ctx *hctx,
+		unsigned int cpu)
 {
-	struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
-			struct blk_mq_hw_ctx, cpuhp_dead);
 	struct blk_mq_ctx *ctx;
 	LIST_HEAD(tmp);
 	enum hctx_type type;
 
-	if (!cpumask_test_cpu(cpu, hctx->cpumask))
-		return 0;
-
 	ctx = __blk_mq_get_ctx(hctx->queue, cpu);
 	type = hctx->type;
 
@@ -2409,13 +2400,27 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
 	spin_unlock(&ctx->lock);
 
 	if (list_empty(&tmp))
-		return 0;
+		return;
 
 	spin_lock(&hctx->lock);
 	list_splice_tail_init(&tmp, &hctx->dispatch);
 	spin_unlock(&hctx->lock);
 
 	blk_mq_run_hw_queue(hctx, true);
+}
+
+/*
+ * 'cpu' is going away. splice any existing rq_list entries from this
+ * software queue to the hw queue dispatch list, and ensure that it
+ * gets run.
+ */
+static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
+{
+	struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
+			struct blk_mq_hw_ctx, cpuhp_dead);
+
+	if (cpumask_test_cpu(cpu, hctx->cpumask))
+		blk_mq_hctx_handle_dead_cpu(hctx, cpu);
 	return 0;
 }
 
-- 
2.25.2