[PATCH linux-next] powerpc: use raw_smp_processor_id in arch_touch_nmi_watchdog
John Ogness
john.ogness at linutronix.de
Thu Jul 14 19:25:00 AEST 2022
On 2022-07-14, Zhouyi Zhou <zhouzhouyi at gmail.com> wrote:
> use raw_smp_processor_id() in arch_touch_nmi_watchdog
> because when called from watchdog, the cpu is preemptible.
I would expect the correct solution is to make it a non-migration
section. Something like the below (untested) patch.
John Ogness
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index bfc27496fe7e..9d34aa809241 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -450,17 +450,23 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
void arch_touch_nmi_watchdog(void)
{
unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
- int cpu = smp_processor_id();
+ int cpu;
u64 tb;
- if (!cpumask_test_cpu(cpu, &watchdog_cpumask))
+ cpu = get_cpu();
+
+ if (!cpumask_test_cpu(cpu, &watchdog_cpumask)) {
+ goto out;
return;
+ }
tb = get_tb();
if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) {
per_cpu(wd_timer_tb, cpu) = tb;
wd_smp_clear_cpu_pending(cpu);
}
+out:
+ put_cpu();
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);
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