X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=72b984c67eb32ddf78733e56025951eef4a84dc0;hb=9213980e6a70d8473e0ffd4b39ab5b6caaba9ff5;hp=fcbb0d5d2817ea5451b60431f66344500095b3d8;hpb=c449269f45c2cdf53af08c8d0af37472f66539d9;p=linux-2.6.git

diff --git a/kernel/cpu.c b/kernel/cpu.c
index fcbb0d5d2..72b984c67 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -20,6 +20,14 @@
 DECLARE_MUTEX(cpucontrol);
 
 static struct notifier_block *cpu_chain;
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+cpumask_t	cpu_present_map;
+EXPORT_SYMBOL(cpu_present_map);
 
 /* Need to know about CPUs going up/down? */
 int register_cpu_notifier(struct notifier_block *nb)
@@ -43,15 +51,16 @@ void unregister_cpu_notifier(struct notifier_block *nb)
 EXPORT_SYMBOL(unregister_cpu_notifier);
 
 #ifdef CONFIG_HOTPLUG_CPU
-static inline void check_for_tasks(int cpu, struct task_struct *k)
+static inline void check_for_tasks(int cpu)
 {
 	struct task_struct *p;
 
 	write_lock_irq(&tasklist_lock);
 	for_each_process(p) {
-		if (task_cpu(p) == cpu && p != k)
-			printk(KERN_WARNING "Task %s is on cpu %d\n",
-				p->comm, cpu);
+		if (task_cpu(p) == cpu && (p->utime != 0 || p->stime != 0))
+			printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
+				(state = %ld, flags = %lx) \n",
+				 p->comm, p->pid, cpu, p->state, p->flags);
 	}
 	write_unlock_irq(&tasklist_lock);
 }
@@ -96,8 +105,9 @@ static int take_cpu_down(void *unused)
 	if (err < 0)
 		cpu_set(smp_processor_id(), cpu_online_map);
 	else
-		/* Everyone else gets kicked off. */
-		migrate_all_tasks();
+		/* Force idle task to run as soon as we yield: it should
+		   immediately notice cpu is offline and die quickly. */
+		sched_idle_next();
 
 	return err;
 }
@@ -106,6 +116,7 @@ int cpu_down(unsigned int cpu)
 {
 	int err;
 	struct task_struct *p;
+	cpumask_t old_allowed, tmp;
 
 	if ((err = lock_cpu_hotplug_interruptible()) != 0)
 		return err;
@@ -120,17 +131,21 @@ int cpu_down(unsigned int cpu)
 		goto out;
 	}
 
+	/* Ensure that we are not runnable on dying cpu */
+	old_allowed = current->cpus_allowed;
+	tmp = CPU_MASK_ALL;
+	cpu_clear(cpu, tmp);
+	set_cpus_allowed(current, tmp);
+
 	p = __stop_machine_run(take_cpu_down, NULL, cpu);
 	if (IS_ERR(p)) {
 		err = PTR_ERR(p);
-		goto out;
+		goto out_allowed;
 	}
 
 	if (cpu_online(cpu))
 		goto out_thread;
 
-	check_for_tasks(cpu, p);
-
 	/* Wait for it to sleep (leaving idle task). */
 	while (!idle_cpu(cpu))
 		yield();
@@ -146,10 +161,14 @@ int cpu_down(unsigned int cpu)
 	    == NOTIFY_BAD)
 		BUG();
 
+	check_for_tasks(cpu);
+
 	cpu_run_sbin_hotplug(cpu, "offline");
 
 out_thread:
 	err = kthread_stop(p);
+out_allowed:
+	set_cpus_allowed(current, old_allowed);
 out:
 	unlock_cpu_hotplug();
 	return err;
@@ -169,7 +188,7 @@ int __devinit cpu_up(unsigned int cpu)
 	if ((ret = down_interruptible(&cpucontrol)) != 0)
 		return ret;
 
-	if (cpu_online(cpu)) {
+	if (cpu_online(cpu) || !cpu_present(cpu)) {
 		ret = -EINVAL;
 		goto out;
 	}