Expand CONFIG_DEBUG_LIST to several other list operations

When list debugging is enabled, we aim to readably show list corruption errors, and the basic list_add/list_del operations end up having extra debugging code in them to do some basic validation of the list entries. However, "list_del_init()" and "list_move[_tail]()" ended up avoiding the debug code due to how they were written. This fixes that. So the _next_ time we have list_move() problems with stale list entries, we'll hopefully have an easier time finding them.. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Expand CONFIG_DEBUG_LIST to several other list operations
When list debugging is enabled, we aim to readably show list corruption errors, and the basic list_add/list_del operations end up having extra debugging code in them to do some basic validation of the list entries. However, "list_del_init()" and "list_move[_tail]()" ended up avoiding the debug code due to how they were written. This fixes that. So the _next_ time we have list_move() problems with stale list entries, we'll hopefully have an easier time finding them.. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds
1 parent 2a324ce7b7
Showing 2 changed files with 35 additions and 16 deletions Side-by-side Diff
include/linux/list.h
lib/list_debug.c
@@ -96,6 +96,11 @@
  * in an undefined state.
  */
 #ifndef CONFIG_DEBUG_LIST
+static inline void __list_del_entry(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+}
+
 static inline void list_del(struct list_head *entry)
 {
 	__list_del(entry->prev, entry->next);
@@ -103,6 +108,7 @@
 	entry->prev = LIST_POISON2;
 }
 #else
+extern void __list_del_entry(struct list_head *entry);
 extern void list_del(struct list_head *entry);
 #endif
  
@@ -135,7 +141,7 @@
  */
 static inline void list_del_init(struct list_head *entry)
 {
-	__list_del(entry->prev, entry->next);
+	__list_del_entry(entry);
 	INIT_LIST_HEAD(entry);
 }
  
@@ -146,7 +152,7 @@
  */
 static inline void list_move(struct list_head *list, struct list_head *head)
 {
-	__list_del(list->prev, list->next);
+	__list_del_entry(list);
 	list_add(list, head);
 }
  
@@ -158,7 +164,7 @@
 static inline void list_move_tail(struct list_head *list,
 				  struct list_head *head)
 {
-	__list_del(list->prev, list->next);
+	__list_del_entry(list);
 	list_add_tail(list, head);
 }
  
@@ -35,6 +35,31 @@
 }
 EXPORT_SYMBOL(__list_add);
  
+void __list_del_entry(struct list_head *entry)
+{
+	struct list_head *prev, *next;
+
+	prev = entry->prev;
+	next = entry->next;
+
+	if (WARN(next == LIST_POISON1,
+		"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
+		entry, LIST_POISON1) ||
+	    WARN(prev == LIST_POISON2,
+		"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
+		entry, LIST_POISON2) ||
+	    WARN(prev->next != entry,
+		"list_del corruption. prev->next should be %p, "
+		"but was %p\n", entry, prev->next) ||
+	    WARN(next->prev != entry,
+		"list_del corruption. next->prev should be %p, "
+		"but was %p\n", entry, next->prev))
+		return;
+
+	__list_del(prev, next);
+}
+EXPORT_SYMBOL(__list_del_entry);
+
 /**
  * list_del - deletes entry from list.
  * @entry: the element to delete from the list.
@@ -43,19 +68,7 @@
  */
 void list_del(struct list_head *entry)
 {
-	WARN(entry->next == LIST_POISON1,
-		"list_del corruption, next is LIST_POISON1 (%p)\n",
-		LIST_POISON1);
-	WARN(entry->next != LIST_POISON1 && entry->prev == LIST_POISON2,
-		"list_del corruption, prev is LIST_POISON2 (%p)\n",
-		LIST_POISON2);
-	WARN(entry->prev->next != entry,
-		"list_del corruption. prev->next should be %p, "
-		"but was %p\n", entry, entry->prev->next);
-	WARN(entry->next->prev != entry,
-		"list_del corruption. next->prev should be %p, "
-		"but was %p\n", entry, entry->next->prev);
-	__list_del(entry->prev, entry->next);
+	__list_del_entry(entry);
 	entry->next = LIST_POISON1;
 	entry->prev = LIST_POISON2;
 }
...	...	@@ -96,6 +96,11 @@
96	96	* in an undefined state.
97	97	*/
98	98	#ifndef CONFIG_DEBUG_LIST
	99	+static inline void __list_del_entry(struct list_head *entry)
	100	+{
	101	+ __list_del(entry->prev, entry->next);
	102	+}
	103	+
99	104	static inline void list_del(struct list_head *entry)
100	105	{
101	106	__list_del(entry->prev, entry->next);
...	...	@@ -103,6 +108,7 @@
103	108	entry->prev = LIST_POISON2;
104	109	}
105	110	#else
	111	+extern void __list_del_entry(struct list_head *entry);
106	112	extern void list_del(struct list_head *entry);
107	113	#endif
108	114
...	...	@@ -135,7 +141,7 @@
135	141	*/
136	142	static inline void list_del_init(struct list_head *entry)
137	143	{
138		- __list_del(entry->prev, entry->next);
	144	+ __list_del_entry(entry);
139	145	INIT_LIST_HEAD(entry);
140	146	}
141	147
...	...	@@ -146,7 +152,7 @@
146	152	*/
147	153	static inline void list_move(struct list_head list, struct list_head head)
148	154	{
149		- __list_del(list->prev, list->next);
	155	+ __list_del_entry(list);
150	156	list_add(list, head);
151	157	}
152	158
...	...	@@ -158,7 +164,7 @@
158	164	static inline void list_move_tail(struct list_head *list,
159	165	struct list_head *head)
160	166	{
161		- __list_del(list->prev, list->next);
	167	+ __list_del_entry(list);
162	168	list_add_tail(list, head);
163	169	}
164	170
...	...	@@ -35,6 +35,31 @@
35	35	}
36	36	EXPORT_SYMBOL(__list_add);
37	37
	38	+void __list_del_entry(struct list_head *entry)
	39	+{
	40	+ struct list_head prev, next;
	41	+
	42	+ prev = entry->prev;
	43	+ next = entry->next;
	44	+
	45	+ if (WARN(next == LIST_POISON1,
	46	+ "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
	47	+ entry, LIST_POISON1) \|\|
	48	+ WARN(prev == LIST_POISON2,
	49	+ "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
	50	+ entry, LIST_POISON2) \|\|
	51	+ WARN(prev->next != entry,
	52	+ "list_del corruption. prev->next should be %p, "
	53	+ "but was %p\n", entry, prev->next) \|\|
	54	+ WARN(next->prev != entry,
	55	+ "list_del corruption. next->prev should be %p, "
	56	+ "but was %p\n", entry, next->prev))
	57	+ return;
	58	+
	59	+ __list_del(prev, next);
	60	+}
	61	+EXPORT_SYMBOL(__list_del_entry);
	62	+
38	63	/**
39	64	* list_del - deletes entry from list.
40	65	* @entry: the element to delete from the list.
...	...	@@ -43,19 +68,7 @@
43	68	*/
44	69	void list_del(struct list_head *entry)
45	70	{
46		- WARN(entry->next == LIST_POISON1,
47		- "list_del corruption, next is LIST_POISON1 (%p)\n",
48		- LIST_POISON1);
49		- WARN(entry->next != LIST_POISON1 && entry->prev == LIST_POISON2,
50		- "list_del corruption, prev is LIST_POISON2 (%p)\n",
51		- LIST_POISON2);
52		- WARN(entry->prev->next != entry,
53		- "list_del corruption. prev->next should be %p, "
54		- "but was %p\n", entry, entry->prev->next);
55		- WARN(entry->next->prev != entry,
56		- "list_del corruption. next->prev should be %p, "
57		- "but was %p\n", entry, entry->next->prev);
58		- __list_del(entry->prev, entry->next);
	71	+ __list_del_entry(entry);
59	72	entry->next = LIST_POISON1;
60	73	entry->prev = LIST_POISON2;
61	74	}