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Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c40
1 files changed, 34 insertions, 6 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index d26d0b095b3..2cc409ce0a8 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -64,6 +64,8 @@ void __init cpu_hotplug_init(void)
cpu_hotplug.refcount = 0;
}
+cpumask_t cpu_active_map;
+
#ifdef CONFIG_HOTPLUG_CPU
void get_online_cpus(void)
@@ -291,11 +293,30 @@ int __ref cpu_down(unsigned int cpu)
int err = 0;
cpu_maps_update_begin();
- if (cpu_hotplug_disabled)
+
+ if (cpu_hotplug_disabled) {
err = -EBUSY;
- else
- err = _cpu_down(cpu, 0);
+ goto out;
+ }
+
+ cpu_clear(cpu, cpu_active_map);
+
+ /*
+ * Make sure the all cpus did the reschedule and are not
+ * using stale version of the cpu_active_map.
+ * This is not strictly necessary becuase stop_machine()
+ * that we run down the line already provides the required
+ * synchronization. But it's really a side effect and we do not
+ * want to depend on the innards of the stop_machine here.
+ */
+ synchronize_sched();
+
+ err = _cpu_down(cpu, 0);
+ if (cpu_online(cpu))
+ cpu_set(cpu, cpu_active_map);
+
+out:
cpu_maps_update_done();
return err;
}
@@ -355,11 +376,18 @@ int __cpuinit cpu_up(unsigned int cpu)
}
cpu_maps_update_begin();
- if (cpu_hotplug_disabled)
+
+ if (cpu_hotplug_disabled) {
err = -EBUSY;
- else
- err = _cpu_up(cpu, 0);
+ goto out;
+ }
+
+ err = _cpu_up(cpu, 0);
+ if (cpu_online(cpu))
+ cpu_set(cpu, cpu_active_map);
+
+out:
cpu_maps_update_done();
return err;
}