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From:   Tejun Heo <tj@kernel.org>
To:     axboe@kernel.dk
Cc:     linux-block@vger.kernel.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-team@fb.com, newella@fb.com,
        Tejun Heo <tj@kernel.org>
Subject: [PATCH 07/27] blk-iocost: make iocg_kick_waitq() call iocg_kick_delay() after paying debt
Date:   Tue,  1 Sep 2020 14:52:37 -0400
Message-Id: <20200901185257.645114-8-tj@kernel.org>
In-Reply-To: <20200901185257.645114-1-tj@kernel.org>
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iocg_kick_waitq() is the function which pays debt and iocg_kick_delay()
updates the actual delay status accordingly. If iocg_kick_delay() is not
called after iocg_kick_delay() updated debt, unnecessarily large delays can
be applied temporarily.

Let's make sure such conditions don't occur by making iocg_kick_waitq()
always call iocg_kick_delay() after paying debt.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 block/blk-iocost.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index ac22d761a350..b2b8dfbeee5a 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1226,6 +1226,8 @@ static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now)
 		atomic64_add(delta, &iocg->vtime);
 		atomic64_add(delta, &iocg->done_vtime);
 		iocg->abs_vdebt -= abs_delta;
+
+		iocg_kick_delay(iocg, now);
 	}
 
 	/*
@@ -1383,7 +1385,6 @@ static void ioc_timer_fn(struct timer_list *timer)
 		if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
 			/* might be oversleeping vtime / hweight changes, kick */
 			iocg_kick_waitq(iocg, &now);
-			iocg_kick_delay(iocg, &now);
 		} else if (iocg_is_idle(iocg)) {
 			/* no waiter and idle, deactivate */
 			iocg->last_inuse = iocg->inuse;
-- 
2.26.2