[Mesa-dev] [PATCH] list: add some iterator debug

[Rob Clark]

From: Rob Clark <robdclark at chromium.org>

Debugging use of unsafe iterators when you should have used the _safe
version sucks.  Add some DEBUG build support to catch and assert if
someone does that.

I didn't update the UPPERCASE verions of the iterators.  They should
probably be deprecated/removed.

Signed-off-by: Rob Clark <robdclark at chromium.org>
---
 src/util/list.h | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/util/list.h b/src/util/list.h
index 09d1b4cae64..6d89a42b226 100644
--- a/src/util/list.h
+++ b/src/util/list.h
@@ -43,6 +43,13 @@
 #include <assert.h>
 #include "c99_compat.h"
 
+#ifdef DEBUG
+#  define LIST_DEBUG 1
+#else
+#  define LIST_DEBUG 0
+#endif
+
+#define list_assert(cond, msg)  ({ if (LIST_DEBUG) assert((cond) && msg); })
 
 struct list_head
 {
@@ -212,21 +219,27 @@ static inline void list_validate(const struct list_head *list)
 	pos = container_of(pos->member.prev, pos, member))
 
 #define list_for_each_entry(type, pos, head, member)                    \
-   for (type *pos = LIST_ENTRY(type, (head)->next, member);             \
+   for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
+	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
 	&pos->member != (head);                                         \
-	pos = LIST_ENTRY(type, pos->member.next, member))
+	pos = LIST_ENTRY(type, pos->member.next, member),               \
+	list_assert(pos == __next, "use _safe iterator"),               \
+	__next = LIST_ENTRY(type, __next->member.next, member))
 
 #define list_for_each_entry_safe(type, pos, head, member)               \
    for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
 	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
 	&pos->member != (head);                                         \
 	pos = __next,                                                   \
-        __next = LIST_ENTRY(type, __next->member.next, member))
+	__next = LIST_ENTRY(type, __next->member.next, member))
 
 #define list_for_each_entry_rev(type, pos, head, member)                \
-   for (type *pos = LIST_ENTRY(type, (head)->prev, member);             \
+   for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
+	     *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
 	&pos->member != (head);                                         \
-	pos = LIST_ENTRY(type, pos->member.prev, member))
+	pos = LIST_ENTRY(type, pos->member.prev, member),               \
+	list_assert(pos == __prev, "use _safe iterator"),               \
+	__prev = LIST_ENTRY(type, __prev->member.prev, member))
 
 #define list_for_each_entry_safe_rev(type, pos, head, member)           \
    for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
-- 
2.20.1