[PATCH v3 2/5] rculist: Consolidate DEBUG_LIST for list_add_rcu()

Kees Cook
2016-08-17T21:43:34Z

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 <keescook@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