linux-kernel - [PATCH 5.10 040/105] dm mpath: only use ktime_get

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Date:   Mon, 18 Apr 2022 14:12:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Khazhismel Kumykov <khazhy@...gle.com>,
        Mike Snitzer <snitzer@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 040/105] dm mpath: only use ktime_get_ns() in historical selector

From: Khazhismel Kumykov <khazhy@...gle.com>

[ Upstream commit ce40426fdc3c92acdba6b5ca74bc7277ffaa6a3d ]

Mixing sched_clock() and ktime_get_ns() usage will give bad results.

Switch hst_select_path() from using sched_clock() to ktime_get_ns().
Also rename path_service_time()'s 'sched_now' variable to 'now'.

Fixes: 2613eab11996 ("dm mpath: add Historical Service Time Path Selector")
Signed-off-by: Khazhismel Kumykov <khazhy@...gle.com>
Signed-off-by: Mike Snitzer <snitzer@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/md/dm-historical-service-time.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-historical-service-time.c b/drivers/md/dm-historical-service-time.c
index 186f91e2752c..06fe43c13ba3 100644
--- a/drivers/md/dm-historical-service-time.c
+++ b/drivers/md/dm-historical-service-time.c
@@ -429,7 +429,7 @@ static struct dm_path *hst_select_path(struct path_selector *ps,
 {
 	struct selector *s = ps->context;
 	struct path_info *pi = NULL, *best = NULL;
-	u64 time_now = sched_clock();
+	u64 time_now = ktime_get_ns();
 	struct dm_path *ret = NULL;
 	unsigned long flags;
 
@@ -470,7 +470,7 @@ static int hst_start_io(struct path_selector *ps, struct dm_path *path,
 
 static u64 path_service_time(struct path_info *pi, u64 start_time)
 {
-	u64 sched_now = ktime_get_ns();
+	u64 now = ktime_get_ns();
 
 	/* if a previous disk request has finished after this IO was
 	 * sent to the hardware, pretend the submission happened
@@ -479,11 +479,11 @@ static u64 path_service_time(struct path_info *pi, u64 start_time)
 	if (time_after64(pi->last_finish, start_time))
 		start_time = pi->last_finish;
 
-	pi->last_finish = sched_now;
-	if (time_before64(sched_now, start_time))
+	pi->last_finish = now;
+	if (time_before64(now, start_time))
 		return 0;
 
-	return sched_now - start_time;
+	return now - start_time;
 }
 
 static int hst_end_io(struct path_selector *ps, struct dm_path *path,
-- 
2.35.1