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 add_work_to_ovs_wq(struct work_struct *work)
  33 {
  34         list_add_tail(&work->entry, &workq);
  35         wake_up(&more_work);
  36 }
  37 static void __queue_work(struct work_struct *work)
  38 {
  39         unsigned long flags;
  40
  41         spin_lock_irqsave(&wq_lock, flags);
  42         add_work_to_ovs_wq(work);
  43         spin_unlock_irqrestore(&wq_lock, flags);
  44 }
  45
  46 void queue_work(struct work_struct *work)
  47 {
  48         if (test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
  49                 return;
  50         __queue_work(work);
  51 }
  52
  53 static void _delayed_work_timer_fn(unsigned long __data)
  54 {
  55         struct delayed_work *dwork = (struct delayed_work *)__data;
  56         __queue_work(&dwork->work);
  57 }
  58
  59 static void __queue_delayed_work(struct delayed_work *dwork,
  60                 unsigned long delay)
  61 {
  62         struct timer_list *timer = &dwork->timer;
  63         struct work_struct *work = &dwork->work;
  64
  65         BUG_ON(timer_pending(timer));
  66         BUG_ON(!list_empty(&work->entry));
  67
  68         timer->expires = jiffies + delay;
  69         timer->data = (unsigned long)dwork;
  70         timer->function = _delayed_work_timer_fn;
  71
  72         add_timer(timer);
  73 }
  74
  75 int schedule_delayed_work(struct delayed_work *dwork, unsigned long delay)
  76 {
  77         if (test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(&dwork->work)))
  78                 return 0;
  79
  80         if (delay == 0)
  81                 __queue_work(&dwork->work);
  82         else
  83                 __queue_delayed_work(dwork, delay);
  84
  85         return 1;
  86 }
  87
  88 struct wq_barrier {
  89         struct work_struct      work;
  90         struct completion       done;
  91 };
  92
  93 static void wq_barrier_func(struct work_struct *work)
  94 {
  95         struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
  96         complete(&barr->done);
  97 }
  98
  99 static void workqueue_barrier(struct work_struct *work)
 100 {
 101         bool need_barrier;
 102         struct wq_barrier barr;
 103
 104         spin_lock_irq(&wq_lock);
 105         if (current_work != work)
 106                 need_barrier = false;
 107         else {
 108                 INIT_WORK(&barr.work, wq_barrier_func);
 109                 init_completion(&barr.done);
 110                 add_work_to_ovs_wq(&barr.work);
 111                 need_barrier = true;
 112         }
 113         spin_unlock_irq(&wq_lock);
 114
 115         if (need_barrier)
 116                 wait_for_completion(&barr.done);
 117 }
 118
 119 static int try_to_grab_pending(struct work_struct *work)
 120 {
 121         int ret;
 122
 123         BUG_ON(in_interrupt());
 124
 125         if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
 126                 return 0;
 127
 128         spin_lock_irq(&wq_lock);
 129         if (!list_empty(&work->entry)) {
 130                 list_del_init(&work->entry);
 131                 ret = 0;
 132         } else
 133                 /* Already executed, retry. */
 134                 ret = -1;
 135         spin_unlock_irq(&wq_lock);
 136
 137         return ret;
 138 }
 139
 140 static int __cancel_work_timer(struct work_struct *work,
 141                                struct timer_list *timer)
 142 {
 143         int ret;
 144
 145         for (;;) {
 146                 ret = (timer && likely(del_timer(timer)));
 147                 if (ret) /* Was active timer, return true. */
 148                         break;
 149
 150                 /* Inactive timer case */
 151                 ret = try_to_grab_pending(work);
 152                 if (!ret)
 153                         break;
 154         }
 155         workqueue_barrier(work);
 156         work_clear_pending(work);
 157         return ret;
 158 }
 159
 160 int cancel_delayed_work_sync(struct delayed_work *dwork)
 161 {
 162         return __cancel_work_timer(&dwork->work, &dwork->timer);
 163 }
 164
 165 bool cancel_work_sync(struct work_struct *work)
 166 {
 167         return __cancel_work_timer(work, NULL);
 168 }
 169
 170 static void run_workqueue(void)
 171 {
 172         spin_lock_irq(&wq_lock);
 173         while (!list_empty(&workq)) {
 174                 struct work_struct *work = list_entry(workq.next,
 175                                 struct work_struct, entry);
 176
 177                 work_func_t f = work->func;
 178                 list_del_init(workq.next);
 179                 current_work = work;
 180                 spin_unlock_irq(&wq_lock);
 181
 182                 work_clear_pending(work);
 183                 f(work);
 184
 185                 BUG_ON(in_interrupt());
 186                 spin_lock_irq(&wq_lock);
 187                 current_work = NULL;
 188         }
 189         spin_unlock_irq(&wq_lock);
 190 }
 191
 192 static int worker_thread(void *dummy)
 193 {
 194         for (;;) {
 195                 wait_event_interruptible(more_work,
 196                                 (kthread_should_stop() || !list_empty(&workq)));
 197
 198                 if (kthread_should_stop())
 199                         break;
 200
 201                 run_workqueue();
 202         }
 203
 204         return 0;
 205 }
 206
 207 int __init ovs_workqueues_init(void)
 208 {
 209         spin_lock_init(&wq_lock);
 210         INIT_LIST_HEAD(&workq);
 211         init_waitqueue_head(&more_work);
 212
 213         workq_thread = kthread_create(worker_thread, NULL, "ovs_workq");
 214         if (IS_ERR(workq_thread))
 215                 return PTR_ERR(workq_thread);
 216
 217         wake_up_process(workq_thread);
 218         return 0;
 219 }
 220
 221 void  ovs_workqueues_exit(void)
 222 {
 223         BUG_ON(!list_empty(&workq));
 224         kthread_stop(workq_thread);
 225 }