[PATCH 07/27] blk-iocost: make iocg_kick_waitq() call iocg_kick_delay() after paying debt

From: Tejun Heo
Date: Tue Sep 01 2020 - 14:56:40 EST


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@xxxxxxxxxx>
---
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