rcu: List-debug variants of rcu list routines.

* Make __list_add_rcu check the next->prev and prev->next pointers just like __list_add does. * Make list_del_rcu use __list_del_entry, which does the same checking at deletion time. Has been running for a week here without anything being tripped up, but it seems worth adding for completeness just in case something ever does corrupt those lists. Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcu: List-debug variants of rcu list routines.
* Make __list_add_rcu check the next->prev and prev->next pointers just like __list_add does. * Make list_del_rcu use __list_del_entry, which does the same checking at deletion time. Has been running for a week here without anything being tripped up, but it seems worth adding for completeness just in case something ever does corrupt those lists. Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Dave Jones · Paul E. McKenney
1 parent 66f75a5d02
Showing 2 changed files with 28 additions and 1 deletions Side-by-side Diff
include/linux/rculist.h
lib/list_debug.c
@@ -30,6 +30,7 @@
  * 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)
 {
@@ -38,6 +39,10 @@
 	rcu_assign_pointer(list_next_rcu(prev), new);
 	next->prev = new;
 }
+#else
+extern 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
@@ -108,7 +113,7 @@
  */
 static inline void list_del_rcu(struct list_head *entry)
 {
-	__list_del(entry->prev, entry->next);
+	__list_del_entry(entry);
 	entry->prev = LIST_POISON2;
 }
  
@@ -10,6 +10,7 @@
 #include <linux/list.h>
 #include <linux/bug.h>
 #include <linux/kernel.h>
+#include <linux/rculist.h>
  
 /*
  * Insert a new entry between two known consecutive entries.
@@ -75,4 +76,25 @@
 	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);
...	...	@@ -30,6 +30,7 @@
30	30	* This is only for internal list manipulation where we know
31	31	* the prev/next entries already!
32	32	*/
	33	+#ifndef CONFIG_DEBUG_LIST
33	34	static inline void __list_add_rcu(struct list_head *new,
34	35	struct list_head prev, struct list_head next)
35	36	{
...	...	@@ -38,6 +39,10 @@
38	39	rcu_assign_pointer(list_next_rcu(prev), new);
39	40	next->prev = new;
40	41	}
	42	+#else
	43	+extern void __list_add_rcu(struct list_head *new,
	44	+ struct list_head prev, struct list_head next);
	45	+#endif
41	46
42	47	/**
43	48	* list_add_rcu - add a new entry to rcu-protected list
...	...	@@ -108,7 +113,7 @@
108	113	*/
109	114	static inline void list_del_rcu(struct list_head *entry)
110	115	{
111		- __list_del(entry->prev, entry->next);
	116	+ __list_del_entry(entry);
112	117	entry->prev = LIST_POISON2;
113	118	}
114	119
...	...	@@ -10,6 +10,7 @@
10	10	#include <linux/list.h>
11	11	#include <linux/bug.h>
12	12	#include <linux/kernel.h>
	13	+#include <linux/rculist.h>
13	14
14	15	/*
15	16	* Insert a new entry between two known consecutive entries.
...	...	@@ -75,4 +76,25 @@
75	76	entry->prev = LIST_POISON2;
76	77	}
77	78	EXPORT_SYMBOL(list_del);
	79	+
	80	+/*
	81	+ * RCU variants.
	82	+ */
	83	+void __list_add_rcu(struct list_head *new,
	84	+ struct list_head prev, struct list_head next)
	85	+{
	86	+ WARN(next->prev != prev,
	87	+ "list_add_rcu corruption. next->prev should be "
	88	+ "prev (%p), but was %p. (next=%p).\n",
	89	+ prev, next->prev, next);
	90	+ WARN(prev->next != next,
	91	+ "list_add_rcu corruption. prev->next should be "
	92	+ "next (%p), but was %p. (prev=%p).\n",
	93	+ next, prev->next, prev);
	94	+ new->next = next;
	95	+ new->prev = prev;
	96	+ rcu_assign_pointer(list_next_rcu(prev), new);
	97	+ next->prev = new;
	98	+}
	99	+EXPORT_SYMBOL(__list_add_rcu);