1 files changed, 75 insertions, 16 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index eebb1d839235..835fe28b87a8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -68,7 +68,7 @@ struct workqueue_struct {
 
 /* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
    threads to each one as cpus come/go. */
-static DEFINE_SPINLOCK(workqueue_lock);
+static DEFINE_MUTEX(workqueue_mutex);
 static LIST_HEAD(workqueues);
 
 static int singlethread_cpu;
@@ -93,9 +93,12 @@ static void __queue_work(struct cpu_workqueue_struct *cwq,
         spin_unlock_irqrestore(&cwq->lock, flags);
 }
 
-/*
- * Queue work on a workqueue. Return non-zero if it was successfully
- * added.
+/**
+ * queue_work - queue work on a workqueue
+ * @wq: workqueue to use
+ * @work: work to queue
+ *
+ * Returns non-zero if it was successfully added.
  *
  * We queue the work to the CPU it was submitted, but there is no
  * guarantee that it will be processed by that CPU.
@@ -128,6 +131,14 @@ static void delayed_work_timer_fn(unsigned long __data)
         __queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
 }
 
+/**
+ * queue_delayed_work - queue work on a workqueue after delay
+ * @wq: workqueue to use
+ * @work: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * Returns non-zero if it was successfully added.
+ */
 int fastcall queue_delayed_work(struct workqueue_struct *wq,
                         struct work_struct *work, unsigned long delay)
 {
@@ -150,6 +161,15 @@ int fastcall queue_delayed_work(struct workqueue_struct *wq,
 }
 EXPORT_SYMBOL_GPL(queue_delayed_work);
 
+/**
+ * queue_delayed_work_on - queue work on specific CPU after delay
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @work: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * Returns non-zero if it was successfully added.
+ */
 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
                         struct work_struct *work, unsigned long delay)
 {
@@ -275,8 +295,9 @@ static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
         }
 }
 
-/*
+/**
  * flush_workqueue - ensure that any scheduled work has run to completion.
+ * @wq: workqueue to flush
  *
  * Forces execution of the workqueue and blocks until its completion.
  * This is typically used in driver shutdown handlers.
@@ -299,10 +320,10 @@ void fastcall flush_workqueue(struct workqueue_struct *wq)
         } else {
                 int cpu;
 
-                lock_cpu_hotplug();
+                mutex_lock(&workqueue_mutex);
                 for_each_online_cpu(cpu)
                         flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
-                unlock_cpu_hotplug();
+                mutex_unlock(&workqueue_mutex);
         }
 }
 EXPORT_SYMBOL_GPL(flush_workqueue);
@@ -350,8 +371,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
         }
 
         wq->name = name;
-        /* We don't need the distraction of CPUs appearing and vanishing. */
-        lock_cpu_hotplug();
+        mutex_lock(&workqueue_mutex);
         if (singlethread) {
                 INIT_LIST_HEAD(&wq->list);
                 p = create_workqueue_thread(wq, singlethread_cpu);
@@ -360,9 +380,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
                 else
                         wake_up_process(p);
         } else {
-                spin_lock(&workqueue_lock);
                 list_add(&wq->list, &workqueues);
-                spin_unlock(&workqueue_lock);
                 for_each_online_cpu(cpu) {
                         p = create_workqueue_thread(wq, cpu);
                         if (p) {
@@ -372,7 +390,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
                                 destroy = 1;
                 }
         }
-        unlock_cpu_hotplug();
+        mutex_unlock(&workqueue_mutex);
 
         /*
          * Was there any error during startup? If yes then clean up:
@@ -400,6 +418,12 @@ static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
                 kthread_stop(p);
 }
 
+/**
+ * destroy_workqueue - safely terminate a workqueue
+ * @wq: target workqueue
+ *
+ * Safely destroy a workqueue. All work currently pending will be done first.
+ */
 void destroy_workqueue(struct workqueue_struct *wq)
 {
         int cpu;
@@ -407,17 +431,15 @@ void destroy_workqueue(struct workqueue_struct *wq)
         flush_workqueue(wq);
 
         /* We don't need the distraction of CPUs appearing and vanishing. */
-        lock_cpu_hotplug();
+        mutex_lock(&workqueue_mutex);
         if (is_single_threaded(wq))
                 cleanup_workqueue_thread(wq, singlethread_cpu);
         else {
                 for_each_online_cpu(cpu)
                         cleanup_workqueue_thread(wq, cpu);
-                spin_lock(&workqueue_lock);
                 list_del(&wq->list);
-                spin_unlock(&workqueue_lock);
         }
-        unlock_cpu_hotplug();
+        mutex_unlock(&workqueue_mutex);
         free_percpu(wq->cpu_wq);
         kfree(wq);
 }
@@ -425,18 +447,41 @@ EXPORT_SYMBOL_GPL(destroy_workqueue);
 
 static struct workqueue_struct *keventd_wq;
 
+/**
+ * schedule_work - put work task in global workqueue
+ * @work: job to be done
+ *
+ * This puts a job in the kernel-global workqueue.
+ */
 int fastcall schedule_work(struct work_struct *work)
 {
         return queue_work(keventd_wq, work);
 }
 EXPORT_SYMBOL(schedule_work);
 
+/**
+ * schedule_delayed_work - put work task in global workqueue after delay
+ * @work: job to be done
+ * @delay: number of jiffies to wait
+ *
+ * After waiting for a given time this puts a job in the kernel-global
+ * workqueue.
+ */
 int fastcall schedule_delayed_work(struct work_struct *work, unsigned long delay)
 {
         return queue_delayed_work(keventd_wq, work, delay);
 }
 EXPORT_SYMBOL(schedule_delayed_work);
 
+/**
+ * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
+ * @cpu: cpu to use
+ * @work: job to be done
+ * @delay: number of jiffies to wait
+ *
+ * After waiting for a given time this puts a job in the kernel-global
+ * workqueue on the specified CPU.
+ */
 int schedule_delayed_work_on(int cpu,
                         struct work_struct *work, unsigned long delay)
 {
@@ -465,11 +510,13 @@ int schedule_on_each_cpu(void (*func)(void *info), void *info)
         if (!works)
                 return -ENOMEM;
 
+        mutex_lock(&workqueue_mutex);
         for_each_online_cpu(cpu) {
                 INIT_WORK(per_cpu_ptr(works, cpu), func, info);
                 __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu),
                                 per_cpu_ptr(works, cpu));
         }
+        mutex_unlock(&workqueue_mutex);
         flush_workqueue(keventd_wq);
         free_percpu(works);
         return 0;
@@ -585,6 +632,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
 
         switch (action) {
         case CPU_UP_PREPARE:
+                mutex_lock(&workqueue_mutex);
                 /* Create a new workqueue thread for it. */
                 list_for_each_entry(wq, &workqueues, list) {
                         if (!create_workqueue_thread(wq, hotcpu)) {
@@ -603,6 +651,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
                         kthread_bind(cwq->thread, hotcpu);
                         wake_up_process(cwq->thread);
                 }
+                mutex_unlock(&workqueue_mutex);
                 break;
 
         case CPU_UP_CANCELED:
@@ -614,6 +663,15 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
                                      any_online_cpu(cpu_online_map));
                         cleanup_workqueue_thread(wq, hotcpu);
                 }
+                mutex_unlock(&workqueue_mutex);
+                break;
+
+        case CPU_DOWN_PREPARE:
+                mutex_lock(&workqueue_mutex);
+                break;
+
+        case CPU_DOWN_FAILED:
+                mutex_unlock(&workqueue_mutex);
                 break;
 
         case CPU_DEAD:
@@ -621,6 +679,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
                         cleanup_workqueue_thread(wq, hotcpu);
                 list_for_each_entry(wq, &workqueues, list)
                         take_over_work(wq, hotcpu);
+                mutex_unlock(&workqueue_mutex);
                 break;
         }