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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /lib/timerqueue.c
parentInitial commit. (diff)
downloadlinux-upstream/4.19.249.tar.xz
linux-upstream/4.19.249.zip
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--lib/timerqueue.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/lib/timerqueue.c b/lib/timerqueue.c
new file mode 100644
index 000000000..7a8ae3d5f
--- /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 library 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/bug.h>
+#include <linux/timerqueue.h>
+#include <linux/rbtree.h>
+#include <linux/export.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. Returns true if the newly added timer is the first expiring timer in
+ * the queue.
+ */
+bool timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
+{
+ struct rb_node **p = &head->rb_root.rb_root.rb_node;
+ struct rb_node *parent = NULL;
+ struct timerqueue_node *ptr;
+ bool leftmost = true;
+
+ /* 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 < ptr->expires) {
+ p = &(*p)->rb_left;
+ } else {
+ p = &(*p)->rb_right;
+ leftmost = false;
+ }
+ }
+ rb_link_node(&node->node, parent, p);
+ rb_insert_color_cached(&node->node, &head->rb_root, leftmost);
+
+ return leftmost;
+}
+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. Returns true if the queue is
+ * not empty after the remove.
+ */
+bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
+{
+ WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
+
+ rb_erase_cached(&node->node, &head->rb_root);
+ RB_CLEAR_NODE(&node->node);
+
+ return !RB_EMPTY_ROOT(&head->rb_root.rb_root);
+}
+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);