Merge branch 'for_rmk_13' of git://git.mnementh.co.uk/linux-2.6-im

[~andy/linux] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b21ba7e9036dfcaa69594827973e3d5d2d2d7970..10ba5f1004a5646bd9960bbe2156291edcb09fb0 100644 (file)
--- 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)
@@ -283,6 +285,11 @@ out_allowed:
        set_cpus_allowed_ptr(current, &old_allowed);
 out_release:
        cpu_hotplug_done();
+       if (!err) {
+               if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+                                           hcpu) == NOTIFY_BAD)
+                       BUG();
+       }
        return err;
 }
 
@@ -291,14 +298,34 @@ 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;
 }
+EXPORT_SYMBOL(cpu_down);
 #endif /*CONFIG_HOTPLUG_CPU*/
 
 /* Requires cpu_add_remove_lock to be held */
@@ -354,11 +381,18 @@ 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;
 }