X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=10ba5f1004a5646bd9960bbe2156291edcb09fb0;hb=d9ecdb282c91952796b7542c4f57fd6de6948d7b;hp=b21ba7e9036dfcaa69594827973e3d5d2d2d7970;hpb=82638844d9a8581bbf33201cc209a14876eca167;p=~andy%2Flinux

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b21ba7e9036..10ba5f1004a 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)
@@ -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;
 }