1 files changed, 250 insertions, 0 deletions
diff --git a/c_src/linux/wait.c b/c_src/linux/wait.c
new file mode 100644
index 00000000..b1f002b9
--- /dev/null
+++ b/c_src/linux/wait.c
@@ -0,0 +1,250 @@
+/*
+ * Generic waiting primitives.
+ *
+ * (C) 2004 Nadia Yvette Chambers, Oracle
+ */
+
+#include <linux/completion.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+
+static inline int waitqueue_active(wait_queue_head_t *q)
+{
+	return !list_empty(&q->task_list);
+}
+
+static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
+{
+	list_add(&new->task_list, &head->task_list);
+}
+
+static inline void __add_wait_queue_tail(wait_queue_head_t *head,
+					 wait_queue_t *new)
+{
+	list_add_tail(&new->task_list, &head->task_list);
+}
+
+static inline void
+__add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
+{
+	wait->flags |= WQ_FLAG_EXCLUSIVE;
+	__add_wait_queue_tail(q, wait);
+}
+
+static inline void
+__remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
+{
+	list_del(&old->task_list);
+}
+
+static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
+			     int nr_exclusive, int wake_flags, void *key)
+{
+	wait_queue_t *curr, *next;
+
+	list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
+		unsigned flags = curr->flags;
+
+		if (curr->func(curr, mode, wake_flags, key) &&
+				(flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
+			break;
+	}
+}
+
+static void __wake_up(wait_queue_head_t *q, unsigned int mode,
+		      int nr_exclusive, void *key)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&q->lock, flags);
+	__wake_up_common(q, mode, nr_exclusive, 0, key);
+	spin_unlock_irqrestore(&q->lock, flags);
+}
+
+void wake_up(wait_queue_head_t *q)
+{
+	__wake_up(q, TASK_NORMAL, 1, NULL);
+}
+
+void wake_up_all(wait_queue_head_t *q)
+{
+	__wake_up(q, TASK_NORMAL, 0, NULL);
+}
+
+static void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr)
+{
+	__wake_up_common(q, mode, nr, 0, NULL);
+}
+
+void
+prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
+{
+	unsigned long flags;
+
+	wait->flags &= ~WQ_FLAG_EXCLUSIVE;
+	spin_lock_irqsave(&q->lock, flags);
+	if (list_empty(&wait->task_list))
+		__add_wait_queue(q, wait);
+	set_current_state(state);
+	spin_unlock_irqrestore(&q->lock, flags);
+}
+
+static void
+prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
+{
+	unsigned long flags;
+
+	wait->flags |= WQ_FLAG_EXCLUSIVE;
+	spin_lock_irqsave(&q->lock, flags);
+	if (list_empty(&wait->task_list))
+		__add_wait_queue_tail(q, wait);
+	set_current_state(state);
+	spin_unlock_irqrestore(&q->lock, flags);
+}
+
+void finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
+{
+	unsigned long flags;
+
+	__set_current_state(TASK_RUNNING);
+	/*
+	 * We can check for list emptiness outside the lock
+	 * IFF:
+	 *  - we use the "careful" check that verifies both
+	 *    the next and prev pointers, so that there cannot
+	 *    be any half-pending updates in progress on other
+	 *    CPU's that we haven't seen yet (and that might
+	 *    still change the stack area.
+	 * and
+	 *  - all other users take the lock (ie we can only
+	 *    have _one_ other CPU that looks at or modifies
+	 *    the list).
+	 */
+	if (!list_empty_careful(&wait->task_list)) {
+		spin_lock_irqsave(&q->lock, flags);
+		list_del_init(&wait->task_list);
+		spin_unlock_irqrestore(&q->lock, flags);
+	}
+}
+
+int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
+			  void *key)
+{
+	return wake_up_process(curr->private);
+}
+
+int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+	int ret = default_wake_function(wait, mode, sync, key);
+
+	if (ret)
+		list_del_init(&wait->task_list);
+	return ret;
+}
+
+struct wait_bit_key {
+	void			*flags;
+	int			bit_nr;
+	unsigned long		timeout;
+};
+
+struct wait_bit_queue {
+	struct wait_bit_key	key;
+	wait_queue_t		wait;
+};
+
+static int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
+{
+	struct wait_bit_key *key = arg;
+	struct wait_bit_queue *wait_bit =
+		container_of(wait, struct wait_bit_queue, wait);
+
+	return (wait_bit->key.flags == key->flags &&
+		wait_bit->key.bit_nr == key->bit_nr &&
+		!test_bit(key->bit_nr, key->flags))
+		? autoremove_wake_function(wait, mode, sync, key) : 0;
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(bit_wq);
+
+#define __WAIT_BIT_KEY_INITIALIZER(word, bit)				\
+	{ .flags = word, .bit_nr = bit, }
+
+#define DEFINE_WAIT_BIT(name, word, bit)				\
+	struct wait_bit_queue name = {					\
+		.key = __WAIT_BIT_KEY_INITIALIZER(word, bit),		\
+		.wait	= {						\
+			.private	= current,			\
+			.func		= wake_bit_function,		\
+			.task_list	=				\
+				LIST_HEAD_INIT((name).wait.task_list),	\
+		},							\
+	}
+
+void wake_up_bit(void *word, int bit)
+{
+	struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
+
+	if (waitqueue_active(&bit_wq))
+		__wake_up(&bit_wq, TASK_NORMAL, 1, &key);
+}
+
+void __wait_on_bit(void *word, int bit, unsigned mode)
+{
+	DEFINE_WAIT_BIT(wait, word, bit);
+
+	do {
+		prepare_to_wait(&bit_wq, &wait.wait, mode);
+		if (test_bit(wait.key.bit_nr, wait.key.flags))
+			schedule();
+	} while (test_bit(wait.key.bit_nr, wait.key.flags));
+
+	finish_wait(&bit_wq, &wait.wait);
+}
+
+void __wait_on_bit_lock(void *word, int bit, unsigned mode)
+{
+	DEFINE_WAIT_BIT(wait, word, bit);
+
+	do {
+		prepare_to_wait_exclusive(&bit_wq, &wait.wait, mode);
+		if (!test_bit(wait.key.bit_nr, wait.key.flags))
+			continue;
+		schedule();
+	} while (test_and_set_bit(wait.key.bit_nr, wait.key.flags));
+	finish_wait(&bit_wq, &wait.wait);
+}
+
+void complete(struct completion *x)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&x->wait.lock, flags);
+	x->done++;
+	__wake_up_locked(&x->wait, TASK_NORMAL, 1);
+	spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+
+void wait_for_completion(struct completion *x)
+{
+	spin_lock_irq(&x->wait.lock);
+
+	if (!x->done) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		__add_wait_queue_tail_exclusive(&x->wait, &wait);
+		do {
+			__set_current_state(TASK_UNINTERRUPTIBLE);
+			spin_unlock_irq(&x->wait.lock);
+
+			schedule();
+			spin_lock_irq(&x->wait.lock);
+		} while (!x->done);
+		__remove_wait_queue(&x->wait, &wait);
+		if (!x->done)
+			goto out;
+	}
+	x->done--;
+out:
+	spin_unlock_irq(&x->wait.lock);
+}