Hi Linus,
Here is the second of the RCU helper patchsets -
This adds a set of list macros that make handling of list protected
by RCU simpler. The interfaces added are -
list_add_rcu
list_add_tail_rcu
- Adds an element by taking care of memory barrier (wmb()).
list_del_rcu
- Deletes an element but doesn't re-initialize the pointers in
the element for supporting RCU based traversal.
list_for_each_rcu
__list_for_each_rcu
- Traversal of RCU protected list - takes care of memory barriers
transparently.
Patch against 2.5.43. Please apply.
Thanks
Dipankar
list.h | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 79 insertions(+)
diff -urN linux-2.5.43-base/include/linux/list.h linux-2.5.43-list_rcu/include/linux/list.h
--- linux-2.5.43-base/include/linux/list.h Sat Oct 12 23:44:44 2002
+++ linux-2.5.43-list_rcu/include/linux/list.h Wed Oct 16 23:10:11 2002
@@ -4,6 +4,7 @@
#if defined(__KERNEL__) || defined(_LVM_H_INCLUDE)
#include <linux/prefetch.h>
+#include <asm/system.h>
/*
* Simple doubly linked list implementation.
@@ -71,6 +72,49 @@
}
/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static __inline__ void __list_add_rcu(struct list_head * new,
+ struct list_head * prev,
+ struct list_head * next)
+{
+ new->next = next;
+ new->prev = prev;
+ wmb();
+ next->prev = new;
+ prev->next = new;
+}
+
+/**
+ * list_add_rcu - add a new entry to rcu-protected list
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static __inline__ void list_add_rcu(struct list_head *new, struct list_head *head)
+{
+ __list_add_rcu(new, head, head->next);
+}
+
+/**
+ * list_add_tail_rcu - add a new entry to rcu-protected list
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static __inline__ void list_add_tail_rcu(struct list_head *new, struct list_head *head)
+{
+ __list_add_rcu(new, head->prev, head);
+}
+
+/*
* Delete a list entry by making the prev/next entries
* point to each other.
*
@@ -93,6 +137,17 @@
{
__list_del(entry->prev, entry->next);
}
+/**
+ * list_del_rcu - deletes entry from list without re-initialization
+ * @entry: the element to delete from the list.
+ * Note: list_empty on entry does not return true after this,
+ * the entry is in an undefined state. It is useful for RCU based
+ * lockfree traversal.
+ */
+static inline void list_del_rcu(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+}
/**
* list_del_init - deletes entry from list and reinitialize it.
@@ -240,6 +295,30 @@
pos = list_entry(pos->member.next, typeof(*pos), member), \
prefetch(pos->member.next))
+/**
+ * list_for_each_rcu - iterate over an rcu-protected list
+ * @pos: the &struct list_head to use as a loop counter.
+ * @head: the head for your list.
+ */
+#define list_for_each_rcu(pos, head) \
+ for (pos = (head)->next, prefetch(pos->next); pos != (head); \
+ pos = pos->next, ({ read_barrier_depends(); 0;}), prefetch(pos->next))
+
+#define __list_for_each_rcu(pos, head) \
+ for (pos = (head)->next; pos != (head); \
+ pos = pos->next, ({ read_barrier_depends(); 0;}))
+
+/**
+ * list_for_each_safe_rcu - iterate over an rcu-protected list safe
+ * against removal of list entry
+ * @pos: the &struct list_head to use as a loop counter.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
+ */
+#define list_for_each_safe_rcu(pos, n, head) \
+ for (pos = (head)->next, n = pos->next; pos != (head); \
+ pos = n, ({ read_barrier_depends(); 0;}), n = pos->next)
+
#endif /* __KERNEL__ || _LVM_H_INCLUDE */
#endif
-
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This archive was generated by hypermail 2b29 : Wed Oct 23 2002 - 22:00:29 EST