From: Christoph Hellwig <hch@lst.de>
Date: Thu, 11 Jun 2020 08:44:42 +0200
Subject: [PATCH] blk-mq: factor out a helper to reise the block softirq
References: bsc#1175995,jsc#SLE-15608
Git-commit: 115243f5534c7b3980cc946e00f79740fdc0e068
Patch-mainline: v5.9-rc1

Add a helper to deduplicate the logic that raises the block softirq.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-mq.c | 31 ++++++++++++++-----------------
 1 file changed, 14 insertions(+), 17 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 96e8a27b8d18..3328d73db53c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -572,19 +572,27 @@ static __latent_entropy void blk_done_softirq(struct softirq_action *h)
 	}
 }
 
-#ifdef CONFIG_SMP
-static void trigger_softirq(void *data)
+static void blk_mq_trigger_softirq(struct request *rq)
 {
-	struct request *rq = data;
-	struct list_head *list;
+	struct list_head *list = this_cpu_ptr(&blk_cpu_done);
 
-	list = this_cpu_ptr(&blk_cpu_done);
 	list_add_tail(&rq->ipi_list, list);
 
+	/*
+	 * If the list only contains our just added request, signal a raise of
+	 * the softirq.  If there are already entries there, someone already
+	 * raised the irq but it hasn't run yet.
+	 */
 	if (list->next == &rq->ipi_list)
 		raise_softirq_irqoff(BLOCK_SOFTIRQ);
 }
 
+#ifdef CONFIG_SMP
+static void trigger_softirq(void *data)
+{
+	blk_mq_trigger_softirq(data);
+}
+
 /*
  * Setup and invoke a run of 'trigger_softirq' on the given cpu.
  */
@@ -655,19 +663,8 @@ static void __blk_complete_request(struct request *req)
 	 * avoids IPI sending from current CPU to the first CPU of a group.
 	 */
 	if (ccpu == cpu || shared) {
-		struct list_head *list;
 do_local:
-		list = this_cpu_ptr(&blk_cpu_done);
-		list_add_tail(&req->ipi_list, list);
-
-		/*
-		 * if the list only contains our just added request,
-		 * signal a raise of the softirq. If there are already
-		 * entries there, someone already raised the irq but it
-		 * hasn't run yet.
-		 */
-		if (list->next == &req->ipi_list)
-			raise_softirq_irqoff(BLOCK_SOFTIRQ);
+		blk_mq_trigger_softirq(req);
 	} else if (raise_blk_irq(ccpu, req))
 		goto do_local;
 
-- 
2.16.4