perf, x86: Fix AMD hotplug & constraint initialization

Commit 3f6da39 ("perf: Rework and fix the arch CPU-hotplug hooks") moved
the amd northbridge allocation from CPUS_ONLINE to CPUS_PREPARE_UP
however amd_nb_id() doesn't work yet on prepare so it would simply bail
basically reverting to a state where we do not properly track node wide
constraints - causing weird perf results.

Fix up the AMD NorthBridge initialization code by allocating from
CPU_UP_PREPARE and installing it from CPU_STARTING once we have the
proper nb_id. It also properly deals with the allocation failing.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[ robustify using amd_has_nb() ]
Signed-off-by: Stephane Eranian <eranian@google.com>
LKML-Reference: <1269353485.5109.48.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 3 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5fb490c6ee5..bd28cf9d8a8 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -158,7 +158,7 @@ struct x86_pmu {
                                                  struct perf_event *event);
         struct event_constraint *event_constraints;
 
-        void            (*cpu_prepare)(int cpu);
+        int             (*cpu_prepare)(int cpu);
         void            (*cpu_starting)(int cpu);
         void            (*cpu_dying)(int cpu);
         void            (*cpu_dead)(int cpu);
@@ -1333,11 +1333,12 @@ static int __cpuinit
 x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 {
         unsigned int cpu = (long)hcpu;
+        int ret = NOTIFY_OK;
 
         switch (action & ~CPU_TASKS_FROZEN) {
         case CPU_UP_PREPARE:
                 if (x86_pmu.cpu_prepare)
-                        x86_pmu.cpu_prepare(cpu);
+                        ret = x86_pmu.cpu_prepare(cpu);
                 break;
 
         case CPU_STARTING:
@@ -1350,6 +1351,7 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
                         x86_pmu.cpu_dying(cpu);
                 break;
 
+        case CPU_UP_CANCELED:
         case CPU_DEAD:
                 if (x86_pmu.cpu_dead)
                         x86_pmu.cpu_dead(cpu);
@@ -1359,7 +1361,7 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
                 break;
         }
 
-        return NOTIFY_OK;
+        return ret;
 }
 
 static void __init pmu_check_apic(void)