--- /dev/null
+/*
+ * 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);
+}
projects / bcachefs-tools-debian / blobdiff