From b78820937b4762b7d30b807d7156bec1d89e4dd3 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 20 Aug 2018 13:20:50 -0600
Subject: [PATCH] blk-wbt: use wq_has_sleeper() for wq active check
Git-commit: b78820937b4762b7d30b807d7156bec1d89e4dd3
Patch-mainline: v4.19-rc1
References: bsc#1135873

We need the memory barrier before checking the list head,
use the appropriate helper for this. The matching queue
side memory barrier is provided by set_current_state().

Tested-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Jan Kara <jack@suse.cz>

---
 block/blk-wbt.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -113,7 +113,7 @@ static void rwb_wake_all(struct rq_wb *r
 	for (i = 0; i < WBT_NUM_RWQ; i++) {
 		struct rq_wait *rqw = &rwb->rq_wait[i];
 
-		if (waitqueue_active(&rqw->wait))
+		if (wq_has_sleeper(&rqw->wait))
 			wake_up_all(&rqw->wait);
 	}
 }
@@ -153,7 +153,7 @@ void __wbt_done(struct rq_wb *rwb, enum
 	if (inflight && inflight >= limit)
 		return;
 
-	if (waitqueue_active(&rqw->wait)) {
+	if (wq_has_sleeper(&rqw->wait)) {
 		int diff = limit - inflight;
 
 		if (!inflight || diff >= rwb->wb_background / 2)
@@ -552,8 +552,8 @@ static void __wbt_wait(struct rq_wb *rwb
 	struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
 	DECLARE_WAITQUEUE(wait, current);
 
-	if (!waitqueue_active(&rqw->wait)
-			&& atomic_inc_below(&rqw->inflight, get_limit(rwb, rw)))
+	if (!wq_has_sleeper(&rqw->wait) &&
+			atomic_inc_below(&rqw->inflight, get_limit(rwb, rw)))
 		return;
 
 	add_wait_queue_exclusive(&rqw->wait, &wait);