[PATCH] add safe version of list_for_each_entry() to list.h

[Mark Peloquin]

Please consider adding the following patch to list.h.

The following patch adds list_for_each_entry_safe() and
list_member() to list.h.

- List_for_each_entry_safe adds a removal-safe version of this macro.
- List_member indicates if the container object is currently in a list.

Thanks.
Mark

diff -Naur old/include/linux/list.h new/include/linux/list.h
--- old/include/linux/list.h  Thu Oct  3 18:06:42 2002
+++ new/include/linux/list.h  Thu Oct  3 18:10:46 2002
@@ -137,6 +137,15 @@
      return head->next == head;
 }

+/**
+ * list_member - tests whether a list member is currently on a list
+ * @member:      member to evaulate
+ */
+static inline int list_member(struct list_head *member)
+{
+     return ((!member->next || !member->prev) ? 0 : 1);
+}
+
 static inline void __list_splice(struct list_head *list,
                         struct list_head *head)
 {
@@ -241,6 +250,20 @@
           pos = list_entry(pos->member.next, typeof(*pos), member),    \
                 prefetch(pos->member.next))

+/**
+ * list_for_each_entry_safe -      iterate over list safe against removal of list entry
+ * @pos:        the type * to use as a loop counter.
+ * @n:                 another type * to use as temporary storage
+ * @head:       the head for your list.
+ * @member:     the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member)                      \
+        for (pos = list_entry((head)->next, typeof(*pos), member),          \
+               n = list_entry(pos->member.next, typeof(*pos), member); \
+           &pos->member != (head);                             \
+           pos = n,                                                    \
+               n = list_entry(pos->member.next, typeof(*pos), member))
+
 #endif /* __KERNEL__ || _LVM_H_INCLUDE */

 #endif