#include <linux/module.h>
#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(cpucontrol);
-static struct notifier_block *cpu_chain;
+static BLOCKING_NOTIFIER_HEAD(cpu_chain);
-/* Need to know about CPUs going up/down? */
-int register_cpu_notifier(struct notifier_block *nb)
+#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;
+ int ret = 0;
+
+ if (lock_cpu_hotplug_owner != current) {
+ if (interruptible)
+ ret = mutex_lock_interruptible(&cpucontrol);
+ else
+ mutex_lock(&cpucontrol);
+ }
+
+ /*
+ * Set only if we succeed in locking
+ */
+ if (!ret) {
+ lock_cpu_hotplug_depth++;
+ lock_cpu_hotplug_owner = current;
+ }
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
- ret = notifier_chain_register(&cpu_chain, nb);
- up(&cpucontrol);
return ret;
}
+
+void lock_cpu_hotplug(void)
+{
+ __lock_cpu_hotplug(0);
+}
+EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
+
+void unlock_cpu_hotplug(void)
+{
+ if (--lock_cpu_hotplug_depth == 0) {
+ lock_cpu_hotplug_owner = NULL;
+ mutex_unlock(&cpucontrol);
+ }
+}
+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 register_cpu_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&cpu_chain, nb);
+}
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);
goto out;
}
- err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+ 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",
p = __stop_machine_run(take_cpu_down, NULL, cpu);
if (IS_ERR(p)) {
/* CPU didn't die: tell everyone. Can't complain. */
- if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
+ if (blocking_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 (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);
int ret;
void *hcpu = (void *)(long)cpu;
- if ((ret = down_interruptible(&cpucontrol)) != 0)
+ if ((ret = lock_cpu_hotplug_interruptible()) != 0)
return ret;
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);
ret = __cpu_up(cpu);
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);
+ blocking_notifier_call_chain(&cpu_chain,
+ CPU_UP_CANCELED, hcpu);
out:
- up(&cpucontrol);
+ unlock_cpu_hotplug();
return ret;
}