void __init cpu_hotplug_init(void)
{
cpu_hotplug.active_writer = NULL;
mutex_init(&cpu_hotplug.lock);
cpu_hotplug.refcount = 0;
void __init cpu_hotplug_init(void)
{
cpu_hotplug.active_writer = NULL;
mutex_init(&cpu_hotplug.lock);
cpu_hotplug.refcount = 0;
- cpu_hotplug.refcount--;
-
- if (unlikely(writer_exists()) && !cpu_hotplug.refcount)
- wake_up(&cpu_hotplug.writer_queue);
-
+ if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
+ wake_up_process(cpu_hotplug.active_writer);
* Note that during a cpu-hotplug operation, the new readers, if any,
* will be blocked by the cpu_hotplug.lock
*
* Note that during a cpu-hotplug operation, the new readers, if any,
* will be blocked by the cpu_hotplug.lock
*
- * Since cpu_maps_update_begin is always called after invoking
- * cpu_maps_update_begin, we can be sure that only one writer is active.
+ * Since cpu_hotplug_begin() is always called after invoking
+ * cpu_maps_update_begin(), we can be sure that only one writer is active.
*
* Note that theoretically, there is a possibility of a livelock:
* - Refcount goes to zero, last reader wakes up the sleeping
*
* Note that theoretically, there is a possibility of a livelock:
* - Refcount goes to zero, last reader wakes up the sleeping
- add_wait_queue_exclusive(&cpu_hotplug.writer_queue, &wait);
- while (cpu_hotplug.refcount) {
- set_current_state(TASK_UNINTERRUPTIBLE);
+
+ for (;;) {
+ mutex_lock(&cpu_hotplug.lock);
+ if (likely(!cpu_hotplug.refcount))
+ break;
+ __set_current_state(TASK_UNINTERRUPTIBLE);
__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
hcpu, nr_calls, NULL);
printk("%s: attempt to take down CPU %u failed\n",
__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
hcpu, nr_calls, NULL);
printk("%s: attempt to take down CPU %u failed\n",