#include <linux/unistd.h>
#include <linux/cpu.h>
#include <linux/module.h>
-#include <linux/kmod.h> /* for hotplug_path */
#include <linux/kthread.h>
#include <linux/stop_machine.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
/* This protects CPUs going up and down... */
-DECLARE_MUTEX(cpucontrol);
+static DEFINE_MUTEX(cpu_add_remove_lock);
+static DEFINE_MUTEX(cpu_bitmask_lock);
-static struct notifier_block *cpu_chain;
+static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);
-/* Need to know about CPUs going up/down? */
-int register_cpu_notifier(struct notifier_block *nb)
+/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
+ * Should always be manipulated under cpu_add_remove_lock
+ */
+static int cpu_hotplug_disabled;
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
+static struct task_struct *recursive;
+static int recursive_depth;
+
+void lock_cpu_hotplug(void)
{
- int ret;
+ struct task_struct *tsk = current;
+
+ if (tsk == recursive) {
+ static int warnings = 10;
+ if (warnings) {
+ printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
+ WARN_ON(1);
+ warnings--;
+ }
+ recursive_depth++;
+ return;
+ }
+ mutex_lock(&cpu_bitmask_lock);
+ recursive = tsk;
+}
+EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
- ret = notifier_chain_register(&cpu_chain, nb);
- up(&cpucontrol);
- return ret;
+void unlock_cpu_hotplug(void)
+{
+ WARN_ON(recursive != current);
+ if (recursive_depth) {
+ recursive_depth--;
+ return;
+ }
+ mutex_unlock(&cpu_bitmask_lock);
+ recursive = NULL;
+}
+EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+/* Need to know about CPUs going up/down? */
+int __cpuinit register_cpu_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&cpu_chain, nb);
}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
EXPORT_SYMBOL(register_cpu_notifier);
void unregister_cpu_notifier(struct notifier_block *nb)
{
- down(&cpucontrol);
- notifier_chain_unregister(&cpu_chain, nb);
- up(&cpucontrol);
+ blocking_notifier_chain_unregister(&cpu_chain, nb);
}
EXPORT_SYMBOL(unregister_cpu_notifier);
-#ifdef CONFIG_HOTPLUG_CPU
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->utime != 0 || p->stime != 0))
+ if (task_cpu(p) == cpu &&
+ (!cputime_eq(p->utime, cputime_zero) ||
+ !cputime_eq(p->stime, cputime_zero)))
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);
}
-/* Notify userspace when a cpu event occurs, by running '/sbin/hotplug
- * cpu' with certain environment variables set. */
-static int cpu_run_sbin_hotplug(unsigned int cpu, const char *action)
-{
- char *argv[3], *envp[5], cpu_str[12], action_str[32];
- int i;
-
- sprintf(cpu_str, "CPU=%d", cpu);
- sprintf(action_str, "ACTION=%s", action);
- /* FIXME: Add DEVPATH. --RR */
-
- i = 0;
- argv[i++] = hotplug_path;
- argv[i++] = "cpu";
- argv[i] = NULL;
-
- i = 0;
- /* minimal command environment */
- envp[i++] = "HOME=/";
- envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
- envp[i++] = cpu_str;
- envp[i++] = action_str;
- envp[i] = NULL;
-
- return call_usermodehelper(argv[0], argv, envp, 0);
-}
-
/* Take this CPU down. */
static int take_cpu_down(void *unused)
{
int err;
- /* Take offline: makes arch_cpu_down somewhat easier. */
- cpu_clear(smp_processor_id(), cpu_online_map);
-
/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
- cpu_set(smp_processor_id(), cpu_online_map);
- else
- /* 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;
- return err;
+ /* Force idle task to run as soon as we yield: it should
+ immediately notice cpu is offline and die quickly. */
+ sched_idle_next();
+ return 0;
}
-int cpu_down(unsigned int cpu)
+/* Requires cpu_add_remove_lock to be held */
+static 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;
+ if (num_online_cpus() == 1)
+ return -EBUSY;
- if (num_online_cpus() == 1) {
- err = -EBUSY;
- goto out;
- }
+ if (!cpu_online(cpu))
+ return -EINVAL;
- if (!cpu_online(cpu)) {
- err = -EINVAL;
- goto out;
+ err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+ (void *)(long)cpu);
+ if (err == NOTIFY_BAD) {
+ printk("%s: attempt to take down CPU %u failed\n",
+ __FUNCTION__, cpu);
+ return -EINVAL;
}
/* Ensure that we are not runnable on dying cpu */
cpu_clear(cpu, tmp);
set_cpus_allowed(current, tmp);
+ mutex_lock(&cpu_bitmask_lock);
p = __stop_machine_run(take_cpu_down, NULL, cpu);
+ mutex_unlock(&cpu_bitmask_lock);
+
if (IS_ERR(p)) {
+ /* CPU didn't die: tell everyone. Can't complain. */
+ if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
+ (void *)(long)cpu) == NOTIFY_BAD)
+ BUG();
+
err = PTR_ERR(p);
goto out_allowed;
}
__cpu_die(cpu);
/* Move it here so it can run. */
- kthread_bind(p, smp_processor_id());
+ kthread_bind(p, get_cpu());
+ put_cpu();
/* CPU is completely dead: tell everyone. Too late to complain. */
- if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
- == NOTIFY_BAD)
+ if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
+ (void *)(long)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;
}
-#else
-static inline int cpu_run_sbin_hotplug(unsigned int cpu, const char *action)
+
+int cpu_down(unsigned int cpu)
{
- return 0;
+ int err = 0;
+
+ mutex_lock(&cpu_add_remove_lock);
+ if (cpu_hotplug_disabled)
+ err = -EBUSY;
+ else
+ err = _cpu_down(cpu);
+
+ mutex_unlock(&cpu_add_remove_lock);
+ return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
-int __devinit cpu_up(unsigned int cpu)
+/* Requires cpu_add_remove_lock to be held */
+static int __devinit _cpu_up(unsigned int cpu)
{
int ret;
void *hcpu = (void *)(long)cpu;
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
+ if (cpu_online(cpu) || !cpu_present(cpu))
+ return -EINVAL;
- if (cpu_online(cpu) || !cpu_present(cpu)) {
- ret = -EINVAL;
- goto out;
- }
- ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
+ ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
if (ret == NOTIFY_BAD) {
printk("%s: attempt to bring up CPU %u failed\n",
__FUNCTION__, cpu);
}
/* Arch-specific enabling code. */
+ mutex_lock(&cpu_bitmask_lock);
ret = __cpu_up(cpu);
+ mutex_unlock(&cpu_bitmask_lock);
if (ret != 0)
goto out_notify;
- if (!cpu_online(cpu))
- BUG();
+ BUG_ON(!cpu_online(cpu));
/* Now call notifier in preparation. */
- notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+ blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
out_notify:
if (ret != 0)
- notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
-out:
- up(&cpucontrol);
+ blocking_notifier_call_chain(&cpu_chain,
+ CPU_UP_CANCELED, hcpu);
+
return ret;
}
+
+int __devinit cpu_up(unsigned int cpu)
+{
+ int err = 0;
+
+ mutex_lock(&cpu_add_remove_lock);
+ if (cpu_hotplug_disabled)
+ err = -EBUSY;
+ else
+ err = _cpu_up(cpu);
+
+ mutex_unlock(&cpu_add_remove_lock);
+ return err;
+}
+
+#ifdef CONFIG_SUSPEND_SMP
+static cpumask_t frozen_cpus;
+
+int disable_nonboot_cpus(void)
+{
+ int cpu, first_cpu, error;
+
+ mutex_lock(&cpu_add_remove_lock);
+ first_cpu = first_cpu(cpu_present_map);
+ if (!cpu_online(first_cpu)) {
+ error = _cpu_up(first_cpu);
+ if (error) {
+ printk(KERN_ERR "Could not bring CPU%d up.\n",
+ first_cpu);
+ goto out;
+ }
+ }
+ error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu));
+ if (error) {
+ printk(KERN_ERR "Could not run on CPU%d\n", first_cpu);
+ goto out;
+ }
+ /* We take down all of the non-boot CPUs in one shot to avoid races
+ * with the userspace trying to use the CPU hotplug at the same time
+ */
+ cpus_clear(frozen_cpus);
+ printk("Disabling non-boot CPUs ...\n");
+ for_each_online_cpu(cpu) {
+ if (cpu == first_cpu)
+ continue;
+ error = _cpu_down(cpu);
+ if (!error) {
+ cpu_set(cpu, frozen_cpus);
+ printk("CPU%d is down\n", cpu);
+ } else {
+ printk(KERN_ERR "Error taking CPU%d down: %d\n",
+ cpu, error);
+ break;
+ }
+ }
+ if (!error) {
+ BUG_ON(num_online_cpus() > 1);
+ /* Make sure the CPUs won't be enabled by someone else */
+ cpu_hotplug_disabled = 1;
+ } else {
+ printk(KERN_ERR "Non-boot CPUs are not disabled");
+ }
+out:
+ mutex_unlock(&cpu_add_remove_lock);
+ return error;
+}
+
+void enable_nonboot_cpus(void)
+{
+ int cpu, error;
+
+ /* Allow everyone to use the CPU hotplug again */
+ mutex_lock(&cpu_add_remove_lock);
+ cpu_hotplug_disabled = 0;
+ mutex_unlock(&cpu_add_remove_lock);
+
+ printk("Enabling non-boot CPUs ...\n");
+ for_each_cpu_mask(cpu, frozen_cpus) {
+ error = cpu_up(cpu);
+ if (!error) {
+ printk("CPU%d is up\n", cpu);
+ continue;
+ }
+ printk(KERN_WARNING "Error taking CPU%d up: %d\n",
+ cpu, error);
+ }
+ cpus_clear(frozen_cpus);
+}
+#endif