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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
commit | 76cb841cb886eef6b3bee341a2266c76578724ad (patch) | |
tree | f5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /lib/timerqueue.c | |
parent | Initial commit. (diff) | |
download | linux-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.c | 107 |
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); |