#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
-#include <linux/mutex.h>
+#include <asm/semaphore.h>
/* This protects CPUs going up and down... */
-static DEFINE_MUTEX(cpu_add_remove_lock);
-static DEFINE_MUTEX(cpu_bitmask_lock);
+static DECLARE_MUTEX(cpucontrol);
-static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);
-
-/* 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;
+static struct notifier_block *cpu_chain;
#ifdef CONFIG_HOTPLUG_CPU
+static struct task_struct *lock_cpu_hotplug_owner;
+static int lock_cpu_hotplug_depth;
+
+static int __lock_cpu_hotplug(int interruptible)
+{
+ int ret = 0;
+
+ if (lock_cpu_hotplug_owner != current) {
+ if (interruptible)
+ ret = down_interruptible(&cpucontrol);
+ else
+ down(&cpucontrol);
+ }
-/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
-static struct task_struct *recursive;
-static int recursive_depth;
+ /*
+ * Set only if we succeed in locking
+ */
+ if (!ret) {
+ lock_cpu_hotplug_depth++;
+ lock_cpu_hotplug_owner = current;
+ }
+
+ return ret;
+}
void lock_cpu_hotplug(void)
{
- 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;
+ __lock_cpu_hotplug(0);
}
EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
void unlock_cpu_hotplug(void)
{
- WARN_ON(recursive != current);
- if (recursive_depth) {
- recursive_depth--;
- return;
+ if (--lock_cpu_hotplug_depth == 0) {
+ lock_cpu_hotplug_owner = NULL;
+ up(&cpucontrol);
}
- mutex_unlock(&cpu_bitmask_lock);
- recursive = NULL;
}
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
+int lock_cpu_hotplug_interruptible(void)
+{
+ return __lock_cpu_hotplug(1);
+}
+EXPORT_SYMBOL_GPL(lock_cpu_hotplug_interruptible);
#endif /* CONFIG_HOTPLUG_CPU */
/* Need to know about CPUs going up/down? */
-int __cpuinit register_cpu_notifier(struct notifier_block *nb)
+int register_cpu_notifier(struct notifier_block *nb)
{
- return blocking_notifier_chain_register(&cpu_chain, nb);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
+ int ret;
+ if ((ret = lock_cpu_hotplug_interruptible()) != 0)
+ return ret;
+ ret = notifier_chain_register(&cpu_chain, nb);
+ unlock_cpu_hotplug();
+ return ret;
+}
EXPORT_SYMBOL(register_cpu_notifier);
void unregister_cpu_notifier(struct notifier_block *nb)
{
- blocking_notifier_chain_unregister(&cpu_chain, nb);
+ lock_cpu_hotplug();
+ notifier_chain_unregister(&cpu_chain, nb);
+ unlock_cpu_hotplug();
}
EXPORT_SYMBOL(unregister_cpu_notifier);
+#ifdef CONFIG_HOTPLUG_CPU
static inline void check_for_tasks(int cpu)
{
struct task_struct *p;
return 0;
}
-/* Requires cpu_add_remove_lock to be held */
-static int _cpu_down(unsigned int cpu)
+int cpu_down(unsigned int cpu)
{
int err;
struct task_struct *p;
cpumask_t old_allowed, tmp;
- if (num_online_cpus() == 1)
- return -EBUSY;
+ if ((err = lock_cpu_hotplug_interruptible()) != 0)
+ return err;
- if (!cpu_online(cpu))
- return -EINVAL;
+ if (num_online_cpus() == 1) {
+ err = -EBUSY;
+ goto out;
+ }
+
+ if (!cpu_online(cpu)) {
+ err = -EINVAL;
+ goto out;
+ }
- err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+ err = 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;
+ err = -EINVAL;
+ goto out;
}
/* 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,
+ if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
(void *)(long)cpu) == NOTIFY_BAD)
BUG();
put_cpu();
/* CPU is completely dead: tell everyone. Too late to complain. */
- if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
- (void *)(long)cpu) == NOTIFY_BAD)
+ if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
+ == NOTIFY_BAD)
BUG();
check_for_tasks(cpu);
err = kthread_stop(p);
out_allowed:
set_cpus_allowed(current, old_allowed);
- return err;
-}
-
-int cpu_down(unsigned int cpu)
-{
- 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);
+out:
+ unlock_cpu_hotplug();
return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
-/* Requires cpu_add_remove_lock to be held */
-static int __devinit _cpu_up(unsigned int cpu)
+int __devinit cpu_up(unsigned int cpu)
{
int ret;
void *hcpu = (void *)(long)cpu;
- if (cpu_online(cpu) || !cpu_present(cpu))
- return -EINVAL;
+ if ((ret = lock_cpu_hotplug_interruptible()) != 0)
+ return ret;
+
+ if (cpu_online(cpu) || !cpu_present(cpu)) {
+ ret = -EINVAL;
+ goto out;
+ }
- ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
+ ret = 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;
- BUG_ON(!cpu_online(cpu));
+ if (!cpu_online(cpu))
+ BUG();
/* Now call notifier in preparation. */
- blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+ notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
out_notify:
if (ret != 0)
- 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");
- }
+ notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
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);
+ unlock_cpu_hotplug();
+ return ret;
}
-#endif
git://git.onelab.eu / linux-2.6.git / blobdiff