list: introduce list_next_entry() and list_prev_entry()

Add two trivial helpers list_next_entry() and list_prev_entry(), they
can have a lot of users including list.h itself.  In fact the 1st one is
already defined in events/core.c and bnx2x_sp.c, so the patch simply
moves the definition to list.h.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eilon Greenstein <eilong@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 16 insertions, 6 deletions

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c
index 9fbeee522d2c..32c92abf5094 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c
@@ -1217,9 +1217,6 @@ static void bnx2x_set_one_vlan_mac_e1h(struct bnx2x *bp,
                                      ETH_VLAN_FILTER_CLASSIFY, config);
 }
 
-#define list_next_entry(pos, member) \
-        list_entry((pos)->member.next, typeof(*(pos)), member)
-
 /**
  * bnx2x_vlan_mac_restore - reconfigure next MAC/VLAN/VLAN-MAC element
  *
diff --git a/include/linux/list.h b/include/linux/list.h
index f4d8a2f12a33..2ece63847001 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -373,6 +373,22 @@ static inline void list_splice_tail_init(struct list_head *list,
         (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
 
 /**
+ * list_next_entry - get the next element in list
+ * @pos:        the type * to cursor
+ * @member:     the name of the list_struct within the struct.
+ */
+#define list_next_entry(pos, member) \
+        list_entry((pos)->member.next, typeof(*(pos)), member)
+
+/**
+ * list_prev_entry - get the prev element in list
+ * @pos:        the type * to cursor
+ * @member:     the name of the list_struct within the struct.
+ */
+#define list_prev_entry(pos, member) \
+        list_entry((pos)->member.prev, typeof(*(pos)), member)
+
+/**
  * list_for_each        -       iterate over a list
  * @pos:        the &struct list_head to use as a loop cursor.
  * @head:       the head for your list.
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8c875ef6e120..d724e7757cd1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2234,9 +2234,6 @@ static void __perf_event_sync_stat(struct perf_event *event,
         perf_event_update_userpage(next_event);
 }
 
-#define list_next_entry(pos, member) \
-        list_entry(pos->member.next, typeof(*pos), member)
-
 static void perf_event_sync_stat(struct perf_event_context *ctx,
                                    struct perf_event_context *next_ctx)
 {