pintos-os.org Git - openvswitch/blob - datapath/linux/compat/workqueue.c

   1 /*
   2  * Derived from the kernel/workqueue.c
   3  *
   4  * This is the generic async execution mechanism.  Work items as are
   5  * executed in process context.
   6  *
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/init.h>
  12 #include <linux/signal.h>
  13 #include <linux/completion.h>
  14 #include <linux/workqueue.h>
  15 #include <linux/slab.h>
  16 #include <linux/cpu.h>
  17 #include <linux/notifier.h>
  18 #include <linux/kthread.h>
  19 #include <linux/hardirq.h>
  20 #include <linux/mempolicy.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/debug_locks.h>
  23 #include <linux/lockdep.h>
  24 #include <linux/idr.h>
  25
  26 static spinlock_t wq_lock;
  27 static struct list_head workq;
  28 static wait_queue_head_t more_work;
  29 static struct task_struct *workq_thread;
  30 static struct work_struct *current_work;
  31
  32 static void queue_work(struct work_struct *work)
  33 {
  34         unsigned long flags;
  35
  36         spin_lock_irqsave(&wq_lock, flags);
  37         list_add_tail(&work->entry, &workq);
  38         wake_up(&more_work);
  39         spin_unlock_irqrestore(&wq_lock, flags);
  40 }
  41
  42 static void _delayed_work_timer_fn(unsigned long __data)
  43 {
  44         struct delayed_work *dwork = (struct delayed_work *)__data;
  45         queue_work(&dwork->work);
  46 }
  47
  48 static void __queue_delayed_work(struct delayed_work *dwork,
  49                 unsigned long delay)
  50 {
  51         struct timer_list *timer = &dwork->timer;
  52         struct work_struct *work = &dwork->work;
  53
  54         BUG_ON(timer_pending(timer));
  55         BUG_ON(!list_empty(&work->entry));
  56
  57         timer->expires = jiffies + delay;
  58         timer->data = (unsigned long)dwork;
  59         timer->function = _delayed_work_timer_fn;
  60
  61         add_timer(timer);
  62 }
  63
  64 int schedule_delayed_work(struct delayed_work *dwork, unsigned long delay)
  65 {
  66         if (test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(&dwork->work)))
  67                 return 0;
  68
  69         if (delay == 0)
  70                 queue_work(&dwork->work);
  71         else
  72                 __queue_delayed_work(dwork, delay);
  73
  74         return 1;
  75 }
  76
  77 struct wq_barrier {
  78         struct work_struct      work;
  79         struct completion       done;
  80 };
  81
  82 static void wq_barrier_func(struct work_struct *work)
  83 {
  84         struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
  85         complete(&barr->done);
  86 }
  87
  88 static void workqueue_barrier(struct work_struct *work)
  89 {
  90         bool need_barrier;
  91         struct wq_barrier barr;
  92
  93         spin_lock_irq(&wq_lock);
  94         if (current_work != work)
  95                 need_barrier = false;
  96         else {
  97                 INIT_WORK(&barr.work, wq_barrier_func);
  98                 init_completion(&barr.done);
  99                 list_add(&barr.work.entry, &workq);
 100                 wake_up(&more_work);
 101                 need_barrier = true;
 102         }
 103         spin_unlock_irq(&wq_lock);
 104
 105         if (need_barrier)
 106                 wait_for_completion(&barr.done);
 107 }
 108
 109 static int try_to_grab_pending(struct work_struct *work)
 110 {
 111         int ret;
 112
 113         BUG_ON(in_interrupt());
 114
 115         if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
 116                 return 0;
 117
 118         spin_lock_irq(&wq_lock);
 119         if (!list_empty(&work->entry)) {
 120                 list_del_init(&work->entry);
 121                 ret = 0;
 122         } else
 123                 /* Already executed, retry. */
 124                 ret = -1;
 125         spin_unlock_irq(&wq_lock);
 126
 127         return ret;
 128 }
 129
 130 static int __cancel_work_timer(struct work_struct *work,
 131                                struct timer_list *timer)
 132 {
 133         int ret;
 134
 135         for (;;) {
 136                 ret = (timer && likely(del_timer(timer)));
 137                 if (ret) /* Was active timer, return true. */
 138                         break;
 139
 140                 /* Inactive timer case */
 141                 ret = try_to_grab_pending(work);
 142                 if (!ret)
 143                         break;
 144         }
 145         workqueue_barrier(work);
 146         work_clear_pending(work);
 147         return ret;
 148 }
 149
 150 int cancel_delayed_work_sync(struct delayed_work *dwork)
 151 {
 152         return __cancel_work_timer(&dwork->work, &dwork->timer);
 153 }
 154
 155 static void run_workqueue(void)
 156 {
 157         spin_lock_irq(&wq_lock);
 158         while (!list_empty(&workq)) {
 159                 struct work_struct *work = list_entry(workq.next,
 160                                 struct work_struct, entry);
 161
 162                 work_func_t f = work->func;
 163                 list_del_init(workq.next);
 164                 current_work = work;
 165                 spin_unlock_irq(&wq_lock);
 166
 167                 work_clear_pending(work);
 168                 f(work);
 169
 170                 BUG_ON(in_interrupt());
 171                 spin_lock_irq(&wq_lock);
 172                 current_work = NULL;
 173         }
 174         spin_unlock_irq(&wq_lock);
 175 }
 176
 177 static int worker_thread(void *dummy)
 178 {
 179         for (;;) {
 180                 wait_event_interruptible(more_work,
 181                                 (kthread_should_stop() || !list_empty(&workq)));
 182
 183                 if (kthread_should_stop())
 184                         break;
 185
 186                 run_workqueue();
 187         }
 188
 189         return 0;
 190 }
 191
 192 int __init ovs_workqueues_init(void)
 193 {
 194         spin_lock_init(&wq_lock);
 195         INIT_LIST_HEAD(&workq);
 196         init_waitqueue_head(&more_work);
 197
 198         workq_thread = kthread_create(worker_thread, NULL, "ovs_workq");
 199         if (IS_ERR(workq_thread))
 200                 return PTR_ERR(workq_thread);
 201
 202         wake_up_process(workq_thread);
 203         return 0;
 204 }
 205
 206 void  ovs_workqueues_exit(void)
 207 {
 208         BUG_ON(!list_empty(&workq));
 209         kthread_stop(workq_thread);
 210 }