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>

diff --git a/lib/list_sort.c b/lib/list_sort.c
index 01aff9e..d7325c6 100644 (file)
--- 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));