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powerpc/watchdog: Do not trigger SMP crash from touch_nmi_watchdog 

In xmon, touch_nmi_watchdog() is not expected to be checking that
other CPUs have not touched the watchdog, so the code will just call
touch_nmi_watchdog() once before re-enabling hard interrupts.

Just update our CPU's state, and ignore apparently stuck SMP threads.

Arguably touch_nmi_watchdog should check for SMP lockups, and callers
should be fixed, but that's not trivial for the input code of xmon.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-09-29 13:29:39 +10:00 committed by Michael Ellerman
parent d58fdd9d7f
commit 80e4d70b06
1 changed files with 5 additions and 2 deletions
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7
arch/powerpc/kernel/watchdog.c
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@ -277,9 +277,12 @@ void arch_touch_nmi_watchdog(void)
{
unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
int cpu = smp_processor_id();
u64 tb = get_tb();
if (get_tb() - per_cpu(wd_timer_tb, cpu) >= ticks)
watchdog_timer_interrupt(cpu);
if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) {
per_cpu(wd_timer_tb, cpu) = tb;
wd_smp_clear_cpu_pending(cpu, tb);
}
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);