From 5b73151fff63fb019db8171cb81c6c978533844b Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 25 Apr 2018 15:17:59 +1000 Subject: powerpc: NMI IPI make NMI IPIs fully sychronous There is an asynchronous aspect to smp_send_nmi_ipi. The caller waits for all CPUs to call in to the handler, but it does not wait for completion of the handler. This is a needless complication, so remove it and always wait synchronously. The synchronous wait allows the caller to easily time out and clear the wait for completion (zero nmi_ipi_busy_count) in the case of badly behaved handlers. This would have prevented the recent smp_send_stop NMI IPI bug from causing the system to hang. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/watchdog.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/powerpc/kernel/watchdog.c') diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index 1d82274f7e9f..3c6ab22a0c4e 100644 --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -174,7 +174,6 @@ static void watchdog_smp_panic(int cpu, u64 tb) continue; smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000); } - smp_flush_nmi_ipi(1000000); } /* Take the stuck CPUs out of the watch group */ -- cgit