patch-2_6_7-vs1_9_1_12

[linux-2.6.git] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index fcbb0d5..72b984c 100644 (file)
--- 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;
        }