From 3d030e301856da366380b3865fce6c03037b08a6 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Thu, 25 Nov 2021 20:33:46 +1000
Subject: [PATCH] powerpc/watchdog: Fix wd_smp_last_reset_tb reporting
References: bsc#1187541 ltc#192129
Patch-mainline: v5.17-rc1
Git-commit: 3d030e301856da366380b3865fce6c03037b08a6
wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of
marking CPUs stuck and removing them from the pending mask before it
begins any printing. This causes last reset times reported to be off.
Fix this by reading it into a local variable before it gets reset.
Fixes: 76521c4b0291 ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/watchdog.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index b6533539386b..23745af38d62 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -179,13 +179,14 @@ static void watchdog_smp_panic(int cpu)
{
static cpumask_t wd_smp_cpus_ipi; // protected by reporting
unsigned long flags;
- u64 tb;
+ u64 tb, last_reset;
int c;
wd_smp_lock(&flags);
/* Double check some things under lock */
tb = get_tb();
- if ((s64)(tb - wd_smp_last_reset_tb) < (s64)wd_smp_panic_timeout_tb)
+ last_reset = wd_smp_last_reset_tb;
+ if ((s64)(tb - last_reset) < (s64)wd_smp_panic_timeout_tb)
goto out;
if (cpumask_test_cpu(cpu, &wd_smp_cpus_pending))
goto out;
@@ -210,8 +211,7 @@ static void watchdog_smp_panic(int cpu)
pr_emerg("CPU %d detected hard LOCKUP on other CPUs %*pbl\n",
cpu, cpumask_pr_args(&wd_smp_cpus_ipi));
pr_emerg("CPU %d TB:%lld, last SMP heartbeat TB:%lld (%lldms ago)\n",
- cpu, tb, wd_smp_last_reset_tb,
- tb_to_ns(tb - wd_smp_last_reset_tb) / 1000000);
+ cpu, tb, last_reset, tb_to_ns(tb - last_reset) / 1000000);
if (!sysctl_hardlockup_all_cpu_backtrace) {
/*
--
2.31.1