linux-kernel - [PATCH 4.19 048/101] tick/common: Touch watchdog in tick

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Message-Id: <20201117122115.431893723@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:05:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chunyan Zhang <chunyan.zhang@...soc.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 4.19 048/101] tick/common: Touch watchdog in tick_unfreeze() on all CPUs

From: Chunyan Zhang <zhang.lyra@...il.com>

commit 5167c506d62dd9ffab73eba23c79b0a8845c9fe1 upstream.

Suspend to IDLE invokes tick_unfreeze() on resume. tick_unfreeze() on the
first resuming CPU resumes timekeeping, which also has the side effect of
resetting the softlockup watchdog on this CPU.

But on the secondary CPUs the watchdog is not reset in the resume /
unfreeze() path, which can result in false softlockup warnings on those
CPUs depending on the time spent in suspend.

Prevent this by clearing the softlock watchdog in the unfreeze path also
on the secondary resuming CPUs.

[ tglx: Massaged changelog ]

Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20200110083902.27276-1-chunyan.zhang@unisoc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/time/tick-common.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -15,6 +15,7 @@
 #include <linux/err.h>
 #include <linux/hrtimer.h>
 #include <linux/interrupt.h>
+#include <linux/nmi.h>
 #include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/sched.h>
@@ -520,6 +521,7 @@ void tick_unfreeze(void)
 		trace_suspend_resume(TPS("timekeeping_freeze"),
 				     smp_processor_id(), false);
 	} else {
+		touch_softlockup_watchdog();
 		tick_resume_local();
 	}