From 8b37bc277fb459fa100808880a9d4e0641fff444 Mon Sep 17 00:00:00 2001
From: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Date: Wed, 13 Nov 2019 15:21:31 +0800
Subject: [PATCH] iocost: check active_list of all the ancestors in
 iocg_activate()
Patch-Mainline: v5.4-rc8
Git-commit: 8b37bc277fb459fa100808880a9d4e0641fff444
References: bsc#1173206

There is a bug that checking the same active_list over and over again
in iocg_activate(). The intention of the code was checking whether all
the ancestors and self have already been activated. So fix it.

Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-iocost.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index a7ed434eae03..e01267f99183 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1057,9 +1057,12 @@ static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
 	atomic64_set(&iocg->active_period, cur_period);
 
 	/* already activated or breaking leaf-only constraint? */
-	for (i = iocg->level; i > 0; i--)
-		if (!list_empty(&iocg->active_list))
+	if (!list_empty(&iocg->active_list))
+		goto succeed_unlock;
+	for (i = iocg->level - 1; i > 0; i--)
+		if (!list_empty(&iocg->ancestors[i]->active_list))
 			goto fail_unlock;
+
 	if (iocg->child_active_sum)
 		goto fail_unlock;
 
@@ -1101,6 +1104,7 @@ static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
 		ioc_start_period(ioc, now);
 	}
 
+succeed_unlock:
 	spin_unlock_irq(&ioc->lock);
 	return true;
 
-- 
2.16.4