linux-kernel - [PATCH] clocksource: Use correct limit for wd-cs-wd read back delay in printing

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Message-ID: <20250731120454.GA309@bytedance>
Date: Thu, 31 Jul 2025 20:04:54 +0800
From: Aaron Lu <ziqianlu@...edance.com>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: John Stultz <jstultz@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
	Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] clocksource: Use correct limit for wd-cs-wd read back delay
 in printing

With commit 4ac1dd3245b9("clocksource: Set cs_watchdog_read() checks
based on .uncertainty_margin"), the limit for wd-cs-wd read back delay
is changed from the static WATCHDOG_MAX_SKEW to dynamic ones based on
watchdog and cs' uncertainty_margin, but WATCHDOG_MAX_SKEW is still used
when dumping information.

Fix this by using the actual limit: md(2 * watchdog->uncertainty_margin)
+ cs->unvertainty_margin.

Signed-off-by: Aaron Lu <ziqianlu@...edance.com>
---
 kernel/time/clocksource.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e400fe150f9d7..ae0fcd5af41c2 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -290,7 +290,7 @@ static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow,
 	}
 
 	pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
-		smp_processor_id(), cs->name, wd_delay, WATCHDOG_MAX_SKEW, wd_seq_delay, nretries, cs->name);
+		smp_processor_id(), cs->name, wd_delay, md + cs->uncertainty_margin, wd_seq_delay, nretries, cs->name);
 	return WD_READ_UNSTABLE;
 
 skip_test:
-- 
2.39.5