[PATCH v2 2/6] powerpc/watchdog: do not backtrace locked CPUs twice if allcpus backtrace is enabled
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2017-09-29 03:30:05
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
If sysctl_hardlockup_all_cpu_backtrace is enabled, there is no need to IPI stuck CPUs for backtrace before trigger_allbutself_cpu_backtrace(), which does the same thing again. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/watchdog.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 532a1adbe89b..920e61c79f47 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c@@ -133,15 +133,18 @@ static void watchdog_smp_panic(int cpu, u64 tb) pr_emerg("Watchdog CPU:%d detected Hard LOCKUP other CPUS:%*pbl\n", cpu, cpumask_pr_args(&wd_smp_cpus_pending)); - /* - * Try to trigger the stuck CPUs. - */ - for_each_cpu(c, &wd_smp_cpus_pending) { - if (c == cpu) - continue; - smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000); + if (!sysctl_hardlockup_all_cpu_backtrace) { + /* + * Try to trigger the stuck CPUs, unless we are going to + * get a backtrace on all of them anyway. + */ + for_each_cpu(c, &wd_smp_cpus_pending) { + if (c == cpu) + continue; + smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000); + } + smp_flush_nmi_ipi(1000000); } - smp_flush_nmi_ipi(1000000); /* Take the stuck CPUs out of the watch group */ set_cpumask_stuck(&wd_smp_cpus_pending, tb);
--
2.13.3