Consolidates the debug checking for list_add_rcu() into the new single
debug function. Notably, this fixes the sanity check that was added in
 commit 17a801f4bfeb ("list_debug: WARN for adding something already in
the list"). Before, it wasn't being checked for RCU lists.

Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 include/linux/rculist.h |  8 +++-----
 lib/list_debug.c        | 19 -------------------
 2 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 8beb98dcf14f..4f7a9561b8c4 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -45,19 +45,17 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head 
*list)
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_add_rcu(struct list_head *new,
                struct list_head *prev, struct list_head *next)
 {
+       if (!__list_add_valid(new, prev, next))
+               return;
+
        new->next = next;
        new->prev = prev;
        rcu_assign_pointer(list_next_rcu(prev), new);
        next->prev = new;
 }
-#else
-void __list_add_rcu(struct list_head *new,
-                   struct list_head *prev, struct list_head *next);
-#endif
 
 /**
  * list_add_rcu - add a new entry to rcu-protected list
diff --git a/lib/list_debug.c b/lib/list_debug.c
index 149dd57b583b..d0b89b9d0736 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -77,22 +77,3 @@ void list_del(struct list_head *entry)
        entry->prev = LIST_POISON2;
 }
 EXPORT_SYMBOL(list_del);
-
-/*
- * RCU variants.
- */
-void __list_add_rcu(struct list_head *new,
-                   struct list_head *prev, struct list_head *next)
-{
-       WARN(next->prev != prev,
-               "list_add_rcu corruption. next->prev should be prev (%p), but 
was %p. (next=%p).\n",
-               prev, next->prev, next);
-       WARN(prev->next != next,
-               "list_add_rcu corruption. prev->next should be next (%p), but 
was %p. (prev=%p).\n",
-               next, prev->next, prev);
-       new->next = next;
-       new->prev = prev;
-       rcu_assign_pointer(list_next_rcu(prev), new);
-       next->prev = new;
-}
-EXPORT_SYMBOL(__list_add_rcu);
-- 
2.7.4

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