Commit 3d030e30 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/watchdog: Fix wd_smp_last_reset_tb reporting 



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: 76521c4b ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi")
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com
parent 4afc78ea

arch/powerpc/kernel/watchdog.c

+4 −4
Original line number Diff line number Diff line
@@ -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) {

		/*