lib/list_sort: test: check element addresses

Improve 'lib_sort()' test and check that:
 o 'cmp()' is called only for elements which were present in the original list,
   i.e., the 'a' and 'b' parameters are valid
 o the resulted (sorted) list consists onlly of the original elements
 o intdoruce "poison" fields to make sure data around 'struc list_head' field
   are not corrupted.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: Don Mullis <don.mullis@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 67 insertions, 8 deletions

diff --git a/lib/list_sort.c b/lib/list_sort.c
index 01aff9e80821..d7325c6b103f 100644
--- a/lib/list_sort.c
+++ b/lib/list_sort.c
@@ -145,23 +145,65 @@ EXPORT_SYMBOL(list_sort);
 
 #include <linux/random.h>
 
+/*
+ * The pattern of set bits in the list length determines which cases
+ * are hit in list_sort().
+ */
+#define TEST_LIST_LEN (512+128+2) /* not including head */
+
+#define TEST_POISON1 0xDEADBEEF
+#define TEST_POISON2 0xA324354C
+
 struct debug_el {
+        unsigned int poison1;
         struct list_head list;
+        unsigned int poison2;
         int value;
         unsigned serial;
 };
 
-static int cmp(void *priv, struct list_head *a, struct list_head *b)
+/* Array, containing pointers to all elements in the test list */
+static struct debug_el **elts __initdata;
+
+static int __init check(struct debug_el *ela, struct debug_el *elb)
 {
-        return container_of(a, struct debug_el, list)->value
-             - container_of(b, struct debug_el, list)->value;
+        if (ela->serial >= TEST_LIST_LEN) {
+                printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
+                                ela->serial);
+                return -EINVAL;
+        }
+        if (elb->serial >= TEST_LIST_LEN) {
+                printk(KERN_ERR "list_sort_test: error: incorrect serial %d\n",
+                                elb->serial);
+                return -EINVAL;
+        }
+        if (elts[ela->serial] != ela || elts[elb->serial] != elb) {
+                printk(KERN_ERR "list_sort_test: error: phantom element\n");
+                return -EINVAL;
+        }
+        if (ela->poison1 != TEST_POISON1 || ela->poison2 != TEST_POISON2) {
+                printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
+                                ela->poison1, ela->poison2);
+                return -EINVAL;
+        }
+        if (elb->poison1 != TEST_POISON1 || elb->poison2 != TEST_POISON2) {
+                printk(KERN_ERR "list_sort_test: error: bad poison: %#x/%#x\n",
+                                elb->poison1, elb->poison2);
+                return -EINVAL;
+        }
+        return 0;
 }
 
-/*
- * The pattern of set bits in the list length determines which cases
- * are hit in list_sort().
- */
-#define TEST_LIST_LEN (512+128+2) /* not including head */
+static int __init cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+        struct debug_el *ela, *elb;
+
+        ela = container_of(a, struct debug_el, list);
+        elb = container_of(b, struct debug_el, list);
+
+        check(ela, elb);
+        return ela->value - elb->value;
+}
 
 static int __init list_sort_test(void)
 {
@@ -172,6 +214,13 @@ static int __init list_sort_test(void)
 
         printk(KERN_DEBUG "list_sort_test: start testing list_sort()\n");
 
+        elts = kmalloc(sizeof(void *) * TEST_LIST_LEN, GFP_KERNEL);
+        if (!elts) {
+                printk(KERN_ERR "list_sort_test: error: cannot allocate "
+                                "memory\n");
+                goto exit;
+        }
+
         for (i = 0; i < TEST_LIST_LEN; i++) {
                 el = kmalloc(sizeof(*el), GFP_KERNEL);
                 if (!el) {
@@ -182,6 +231,9 @@ static int __init list_sort_test(void)
                  /* force some equivalencies */
                 el->value = random32() % (TEST_LIST_LEN/3);
                 el->serial = i;
+                el->poison1 = TEST_POISON1;
+                el->poison2 = TEST_POISON2;
+                elts[i] = el;
                 list_add_tail(&el->list, &head);
         }
 
@@ -211,6 +263,12 @@ static int __init list_sort_test(void)
                                         "equivalent elements not preserved\n");
                         goto exit;
                 }
+
+                if (check(el, el1)) {
+                        printk(KERN_ERR "list_sort_test: error: element check "
+                                        "failed\n");
+                        goto exit;
+                }
                 count++;
         }
 
@@ -222,6 +280,7 @@ static int __init list_sort_test(void)
 
         err = 0;
 exit:
+        kfree(elts);
         list_for_each_safe(cur, tmp, &head) {
                 list_del(cur);
                 kfree(container_of(cur, struct debug_el, list));