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Date: Fri, 15 Oct 2010 17:38:51 -0700
From: John Stultz <john.stultz@...aro.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: John Stultz <john.stultz@...aro.org>,
Alessandro Zummo <a.zummo@...ertech.it>,
Thomas Gleixner <tglx@...utronix.de>,
Richard Cochran <richardcochran@...il.com>
Subject: [PATCH 2/6] [RFC] Introduce timerlist infrastructure.
The timerlist infrastructure is a thin layer over the rbtree
code that implements a simple list of timers sorted by an
expires value, and a getnext function that provides a pointer
to the earliest timer.
This infrastructure allows drivers and other kernel infrastructure
to easily implement timers without duplicating code.
Suggestions or feedback would be appreciated.
Signed-off-by: John Stultz <john.stultz@...aro.org>
CC: Alessandro Zummo <a.zummo@...ertech.it>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Richard Cochran <richardcochran@...il.com>
---
include/linux/timerlist.h | 37 ++++++++++++++
lib/Makefile | 2 +-
lib/timerlist.c | 115 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 153 insertions(+), 1 deletions(-)
create mode 100644 include/linux/timerlist.h
create mode 100644 lib/timerlist.c
diff --git a/include/linux/timerlist.h b/include/linux/timerlist.h
new file mode 100644
index 0000000..c46b28a
--- /dev/null
+++ b/include/linux/timerlist.h
@@ -0,0 +1,37 @@
+#ifndef _LINUX_TIMERLIST_H
+#define _LINUX_TIMERLIST_H
+
+#include <linux/rbtree.h>
+#include <linux/ktime.h>
+
+
+struct timerlist_node {
+ struct rb_node node;
+ ktime_t expires;
+};
+
+struct timerlist_head {
+ struct rb_root head;
+ struct timerlist_node *next;
+};
+
+
+extern void timerlist_add(struct timerlist_head *head,
+ struct timerlist_node *node);
+extern void timerlist_del(struct timerlist_head *head,
+ struct timerlist_node *node);
+extern struct timerlist_node *timerlist_getnext(struct timerlist_head *head);
+extern struct timerlist_node *timerlist_iterate_next(
+ struct timerlist_node *node);
+
+static inline void timerlist_init(struct timerlist_node *node)
+{
+ RB_CLEAR_NODE(&node->node);
+}
+
+static inline void timerlist_init_head(struct timerlist_head *head)
+{
+ head->head = RB_ROOT;
+ head->next = NULL;
+}
+#endif /* _LINUX_TIMERLIST_H */
diff --git a/lib/Makefile b/lib/Makefile
index e6a3763..8b475cf 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -8,7 +8,7 @@ KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
endif
lib-y := ctype.o string.o vsprintf.o cmdline.o \
- rbtree.o radix-tree.o dump_stack.o \
+ rbtree.o radix-tree.o dump_stack.o timerlist.o\
idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o irq_regs.o reciprocal_div.o argv_split.o \
proportions.o prio_heap.o ratelimit.o show_mem.o \
diff --git a/lib/timerlist.c b/lib/timerlist.c
new file mode 100644
index 0000000..3301b45
--- /dev/null
+++ b/lib/timerlist.c
@@ -0,0 +1,115 @@
+/*
+ * Generic Timer-list
+ *
+ * Manages a simple list 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/timerlist.h>
+#include <linux/rbtree.h>
+
+/**
+ * timerlist_add - Adds timer to timerlist.
+ *
+ * @head: head of timerlist
+ * @node: timer node to be added
+ *
+ * Adds the timer node to the timerlist, sorted by the
+ * node's expires value.
+ */
+void timerlist_add(struct timerlist_head *head, struct timerlist_node *node)
+{
+ struct rb_node **p = &head->head.rb_node;
+ struct rb_node *parent = NULL;
+ struct timerlist_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 timerlist_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;
+}
+
+/**
+ * timerlist_del - Removes a timer from the timerlist.
+ *
+ * @head: head of timerlist
+ * @node: timer node to be removed
+ *
+ * Removes the timer node from the timerlist.
+ */
+void timerlist_del(struct timerlist_head *head, struct timerlist_node *node)
+{
+ WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));
+
+ /* update next pointer */
+ if (head->next == node)
+ head->next = rb_entry(rb_next(&node->node),
+ struct timerlist_node, node);
+ rb_erase(&node->node, &head->head);
+ RB_CLEAR_NODE(&node->node);
+}
+
+
+/**
+ * timerlist_getnext - Returns the timer with the earlies expiration time
+ *
+ * @head: head of timerlist
+ *
+ * Returns a pointer to the timer node that has the
+ * earliest expiration time.
+ */
+struct timerlist_node *timerlist_getnext(struct timerlist_head *head)
+{
+ return head->next;
+}
+
+
+/**
+ * timerlist_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 timerlist_node *timerlist_iterate_next(struct timerlist_node *node)
+{
+ struct rb_node *next;
+
+ if (!node)
+ return NULL;
+ next = rb_next(&node->node);
+ if (!next)
+ return NULL;
+ return container_of(next, struct timerlist_node, node);
+}
--
1.6.0.4
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