lib: list_sort.c: Limit number of unused cmp callbacks

[deliverable/linux.git] / lib / list_sort.c

diff --git a/lib/list_sort.c b/lib/list_sort.c
index 1183fa70a44d26cfc673b6d5d2f645b7026f50dd..6b9fdaf1d32e52ebcbb22ceb632d2a90388e7d63 100644 (file)
--- a/lib/list_sort.c
+++ b/lib/list_sort.c
@@ -47,6 +47,7 @@ static void merge_and_restore_back_links(void *priv,
                                struct list_head *a, struct list_head *b)
 {
        struct list_head *tail = head;
+       u8 count = 0;
 
        while (a && b) {
                /* if equal, take 'a' -- important for sort stability */
@@ -70,7 +71,8 @@ static void merge_and_restore_back_links(void *priv,
                 * element comparison is needed, so the client's cmp()
                 * routine can invoke cond_resched() periodically.
                 */
-               (*cmp)(priv, tail->next, tail->next);
+               if (unlikely(!(++count)))
+                       (*cmp)(priv, tail->next, tail->next);
 
                tail->next->prev = tail;
                tail = tail->next;
@@ -207,18 +209,18 @@ static int __init cmp(void *priv, struct list_head *a, struct list_head *b)
 
 static int __init list_sort_test(void)
 {
-       int i, count = 1, err = -EINVAL;
+       int i, count = 1, err = -ENOMEM;
        struct debug_el *el;
-       struct list_head *cur, *tmp;
+       struct list_head *cur;
        LIST_HEAD(head);
 
        printk(KERN_DEBUG "list_sort_test: start testing list_sort()\n");
 
-       elts = kmalloc(sizeof(void *) * TEST_LIST_LEN, GFP_KERNEL);
+       elts = kcalloc(TEST_LIST_LEN, sizeof(*elts), GFP_KERNEL);
        if (!elts) {
                printk(KERN_ERR "list_sort_test: error: cannot allocate "
                                "memory\n");
-               goto exit;
+               return err;
        }
 
        for (i = 0; i < TEST_LIST_LEN; i++) {
@@ -239,6 +241,7 @@ static int __init list_sort_test(void)
 
        list_sort(NULL, &head, cmp);
 
+       err = -EINVAL;
        for (cur = head.next; cur->next != &head; cur = cur->next) {
                struct debug_el *el1;
                int cmp_result;
@@ -271,6 +274,11 @@ static int __init list_sort_test(void)
                }
                count++;
        }
+       if (head.prev != cur) {
+               printk(KERN_ERR "list_sort_test: error: list is corrupted\n");
+               goto exit;
+       }
+
 
        if (count != TEST_LIST_LEN) {
                printk(KERN_ERR "list_sort_test: error: bad list length %d",
@@ -280,11 +288,9 @@ static int __init list_sort_test(void)
 
        err = 0;
 exit:
+       for (i = 0; i < TEST_LIST_LEN; i++)
+               kfree(elts[i]);
        kfree(elts);
-       list_for_each_safe(cur, tmp, &head) {
-               list_del(cur);
-               kfree(container_of(cur, struct debug_el, list));
-       }
        return err;
 }
 module_init(list_sort_test);