list: introduce list_first_entry_or_null

[pandora-kernel.git] / include / linux / list.h

diff --git a/include/linux/list.h b/include/linux/list.h
index 3a54266..7690738 100644 (file)
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -4,7 +4,7 @@
 #include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/poison.h>
-#include <linux/prefetch.h>
+#include <linux/const.h>
 
 /*
  * Simple doubly linked list implementation.
@@ -361,24 +361,32 @@ static inline void list_splice_tail_init(struct list_head *list,
 #define list_first_entry(ptr, type, member) \
        list_entry((ptr)->next, type, member)
 
+/**
+ * list_first_entry_or_null - get the first element from a list
+ * @ptr:       the list head to take the element from.
+ * @type:      the type of the struct this is embedded in.
+ * @member:    the name of the list_struct within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null(ptr, type, member) \
+       (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+
 /**
  * list_for_each       -       iterate over a list
  * @pos:       the &struct list_head to use as a loop cursor.
  * @head:      the head for your list.
  */
 #define list_for_each(pos, head) \
-       for (pos = (head)->next; prefetch(pos->next), pos != (head); \
-               pos = pos->next)
+       for (pos = (head)->next; pos != (head); pos = pos->next)
 
 /**
  * __list_for_each     -       iterate over a list
  * @pos:       the &struct list_head to use as a loop cursor.
  * @head:      the head for your list.
  *
- * This variant differs from list_for_each() in that it's the
- * simplest possible list iteration code, no prefetching is done.
- * Use this for code that knows the list to be very short (empty
- * or 1 entry) most of the time.
+ * This variant doesn't differ from list_for_each() any more.
+ * We don't do prefetching in either case.
  */
 #define __list_for_each(pos, head) \
        for (pos = (head)->next; pos != (head); pos = pos->next)
@@ -389,8 +397,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  * @head:      the head for your list.
  */
 #define list_for_each_prev(pos, head) \
-       for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
-               pos = pos->prev)
+       for (pos = (head)->prev; pos != (head); pos = pos->prev)
 
 /**
  * list_for_each_safe - iterate over a list safe against removal of list entry
@@ -410,7 +417,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  */
 #define list_for_each_prev_safe(pos, n, head) \
        for (pos = (head)->prev, n = pos->prev; \
-            prefetch(pos->prev), pos != (head); \
+            pos != (head); \
             pos = n, n = pos->prev)
 
 /**
@@ -421,7 +428,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  */
 #define list_for_each_entry(pos, head, member)                         \
        for (pos = list_entry((head)->next, typeof(*pos), member);      \
-            prefetch(pos->member.next), &pos->member != (head);        \
+            &pos->member != (head);    \
             pos = list_entry(pos->member.next, typeof(*pos), member))
 
 /**
@@ -432,7 +439,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  */
 #define list_for_each_entry_reverse(pos, head, member)                 \
        for (pos = list_entry((head)->prev, typeof(*pos), member);      \
-            prefetch(pos->member.prev), &pos->member != (head);        \
+            &pos->member != (head);    \
             pos = list_entry(pos->member.prev, typeof(*pos), member))
 
 /**
@@ -457,7 +464,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  */
 #define list_for_each_entry_continue(pos, head, member)                \
        for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
-            prefetch(pos->member.next), &pos->member != (head);        \
+            &pos->member != (head);    \
             pos = list_entry(pos->member.next, typeof(*pos), member))
 
 /**
@@ -471,7 +478,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  */
 #define list_for_each_entry_continue_reverse(pos, head, member)                \
        for (pos = list_entry(pos->member.prev, typeof(*pos), member);  \
-            prefetch(pos->member.prev), &pos->member != (head);        \
+            &pos->member != (head);    \
             pos = list_entry(pos->member.prev, typeof(*pos), member))
 
 /**
@@ -483,7 +490,7 @@ static inline void list_splice_tail_init(struct list_head *list,
  * Iterate over list of given type, continuing from current position.
  */
 #define list_for_each_entry_from(pos, head, member)                    \
-       for (; prefetch(pos->member.next), &pos->member != (head);      \
+       for (; &pos->member != (head);  \
             pos = list_entry(pos->member.next, typeof(*pos), member))
 
 /**
@@ -664,8 +671,7 @@ static inline void hlist_move_list(struct hlist_head *old,
 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
 
 #define hlist_for_each(pos, head) \
-       for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
-            pos = pos->next)
+       for (pos = (head)->first; pos ; pos = pos->next)
 
 #define hlist_for_each_safe(pos, n, head) \
        for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
@@ -680,7 +686,7 @@ static inline void hlist_move_list(struct hlist_head *old,
  */
 #define hlist_for_each_entry(tpos, pos, head, member)                   \
        for (pos = (head)->first;                                        \
-            pos && ({ prefetch(pos->next); 1;}) &&                      \
+            pos &&                                                      \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
             pos = pos->next)
 
@@ -692,7 +698,7 @@ static inline void hlist_move_list(struct hlist_head *old,
  */
 #define hlist_for_each_entry_continue(tpos, pos, member)                \
        for (pos = (pos)->next;                                          \
-            pos && ({ prefetch(pos->next); 1;}) &&                      \
+            pos &&                                                      \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
             pos = pos->next)
 
@@ -703,7 +709,7 @@ static inline void hlist_move_list(struct hlist_head *old,
  * @member:    the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_from(tpos, pos, member)                    \
-       for (; pos && ({ prefetch(pos->next); 1;}) &&                    \
+       for (; pos &&                                                    \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
             pos = pos->next)