Commit 80e4d70b authored Sep 29, 2017 by Nicholas Piggin Committed by Michael Ellerman Oct 04, 2017

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>

parent d58fdd9d

arch/powerpc/kernel/watchdog.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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);