powerpc/watchdog: Do not backtrace locked CPUs twice if allcpus backtrace is enabled

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 532a1adbe89bb0e3a6604e83241e9a4f2492030f..920e61c79f47775b726e0747e67765c16d2e4c86 100644 (file)
--- 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);