1 files changed, 107 insertions, 0 deletions

diff --git a/lib/timerqueue.c b/lib/timerqueue.c
new file mode 100644
index 000000000000..e3a1050e6820
--- /dev/null
+++ b/lib/timerqueue.c
@@ -0,0 +1,107 @@
+/*
+ *  Generic Timer-queue
+ *
+ *  Manages a simple queue of timers, ordered by expiration time.
+ *  Uses rbtrees for quick list adds and expiration.
+ *
+ *  NOTE: All of the following functions need to be serialized
+ *  to avoid races. No locking is done by this libary code.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/timerqueue.h>
+#include <linux/rbtree.h>
+#include <linux/module.h>
+
+/**
+ * timerqueue_add - Adds timer to timerqueue.
+ *
+ * @head: head of timerqueue
+ * @node: timer node to be added
+ *
+ * Adds the timer node to the timerqueue, sorted by the
+ * node's expires value.
+ */
+void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
+{
+        struct rb_node **p = &head->head.rb_node;
+        struct rb_node *parent = NULL;
+        struct timerqueue_node  *ptr;
+
+        /* Make sure we don't add nodes that are already added */
+        WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));
+
+        while (*p) {
+                parent = *p;
+                ptr = rb_entry(parent, struct timerqueue_node, node);
+                if (node->expires.tv64 < ptr->expires.tv64)
+                        p = &(*p)->rb_left;
+                else
+                        p = &(*p)->rb_right;
+        }
+        rb_link_node(&node->node, parent, p);
+        rb_insert_color(&node->node, &head->head);
+
+        if (!head->next || node->expires.tv64 < head->next->expires.tv64)
+                head->next = node;
+}
+EXPORT_SYMBOL_GPL(timerqueue_add);
+
+/**
+ * timerqueue_del - Removes a timer from the timerqueue.
+ *
+ * @head: head of timerqueue
+ * @node: timer node to be removed
+ *
+ * Removes the timer node from the timerqueue.
+ */
+void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
+{
+        WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
+
+        /* update next pointer */
+        if (head->next == node) {
+                struct rb_node *rbn = rb_next(&node->node);
+
+                head->next = rbn ?
+                        rb_entry(rbn, struct timerqueue_node, node) : NULL;
+        }
+        rb_erase(&node->node, &head->head);
+        RB_CLEAR_NODE(&node->node);
+}
+EXPORT_SYMBOL_GPL(timerqueue_del);
+
+/**
+ * timerqueue_iterate_next - Returns the timer after the provided timer
+ *
+ * @node: Pointer to a timer.
+ *
+ * Provides the timer that is after the given node. This is used, when
+ * necessary, to iterate through the list of timers in a timer list
+ * without modifying the list.
+ */
+struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
+{
+        struct rb_node *next;
+
+        if (!node)
+                return NULL;
+        next = rb_next(&node->node);
+        if (!next)
+                return NULL;
+        return container_of(next, struct timerqueue_node, node);
+}
+EXPORT_SYMBOL_GPL(timerqueue_iterate_next);