[PATCH] Debug variants of linked list macros

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/lib/list_debug.c b/lib/list_debug.c
new file mode 100644
index 00000000000..1aae85cef92
--- /dev/null
+++ b/lib/list_debug.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2006, Red Hat, Inc., Dave Jones
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the linked list implementations for
+ * DEBUG_LIST.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+
+void __list_add(struct list_head *new,
+			      struct list_head *prev,
+			      struct list_head *next)
+{
+	if (unlikely(next->prev != prev)) {
+		printk(KERN_ERR "list_add corruption. next->prev should be %p, but was %p\n",
+			prev, next->prev);
+		BUG();
+	}
+	if (unlikely(prev->next != next)) {
+		printk(KERN_ERR "list_add corruption. prev->next should be %p, but was %p\n",
+			next, prev->next);
+		BUG();
+	}
+	next->prev = new;
+	new->next = next;
+	new->prev = prev;
+	prev->next = new;
+}
+EXPORT_SYMBOL(__list_add);
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+void list_add(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head, head->next);
+}
+EXPORT_SYMBOL(list_add);
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+void list_del(struct list_head *entry)
+{
+	if (unlikely(entry->prev->next != entry)) {
+		printk(KERN_ERR "list_del corruption. prev->next should be %p, but was %p\n",
+			entry, entry->prev->next);
+		BUG();
+	}
+	if (unlikely(entry->next->prev != entry)) {
+		printk(KERN_ERR "list_del corruption. next->prev should be %p, but was %p\n",
+			entry, entry->next->prev);
+		BUG();
+	}
+	__list_del(entry->prev, entry->next);
+	entry->next = LIST_POISON1;
+	entry->prev = LIST_POISON2;
+}
+EXPORT_SYMBOL(list_del);
+