From 694123031d12458a343492528fa40113e5ec843e Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Wed, 6 Aug 2014 16:09:42 -0700 Subject: [PATCH] lib: list_sort_test(): simplify and harden cleanup There is no reason to maintain the list structure while freeing the debug elements. Aside from the redundant pointer manipulations, it is also inefficient from a locality-of-reference viewpoint, since they are visited in a random order (wrt. the order they were allocated). Furthermore, if we jumped to exit: after detecting list corruption, it is actually dangerous. So just free the elements in the order they were allocated, using the backing array elts. Allocate that using kcalloc(), so that if allocation of one of the debug element fails, we just end up calling kfree(NULL) for the trailing elements. Minor details: Use sizeof(*elts) instead of sizeof(void *), and return err immediately when allocation of elts fails, to avoid introducing another label just before the final return statement. Signed-off-by: Rasmus Villemoes Cc: Artem Bityutskiy Cc: Don Mullis Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/list_sort.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/lib/list_sort.c b/lib/list_sort.c index fbdbc867b252..a34c78c30d56 100644 --- a/lib/list_sort.c +++ b/lib/list_sort.c @@ -209,16 +209,16 @@ static int __init list_sort_test(void) { 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++) { @@ -286,11 +286,9 @@ 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); -- GitLab