From b7b2562f7252878e18de60c24f320052076f9de8 Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Mon, 10 Jul 2017 15:51:17 -0700
Subject: [PATCH] kernel/groups.c: use sort library function
setgroups is not exactly a hot path, so we might as well use the library
function instead of open-coding the sorting. Saves ~150 bytes.
Link: http://lkml.kernel.org/r/1497301378-22739-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/groups.c | 35 +++++++++++------------------------
1 file changed, 11 insertions(+), 24 deletions(-)
diff --git a/kernel/groups.c b/kernel/groups.c
index d09727692a2af..434f6665f187d 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -5,6 +5,7 @@
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/security.h>
+#include <linux/sort.h>
#include <linux/syscalls.h>
#include <linux/user_namespace.h>
#include <linux/vmalloc.h>
@@ -76,32 +77,18 @@ static int groups_from_user(struct group_info *group_info,
return 0;
}
-/* a simple Shell sort */
+static int gid_cmp(const void *_a, const void *_b)
+{
+ kgid_t a = *(kgid_t *)_a;
+ kgid_t b = *(kgid_t *)_b;
+
+ return gid_gt(a, b) - gid_lt(a, b);
+}
+
static void groups_sort(struct group_info *group_info)
{
- int base, max, stride;
- int gidsetsize = group_info->ngroups;
-
- for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
- ; /* nothing */
- stride /= 3;
-
- while (stride) {
- max = gidsetsize - stride;
- for (base = 0; base < max; base++) {
- int left = base;
- int right = left + stride;
- kgid_t tmp = group_info->gid[right];
-
- while (left >= 0 && gid_gt(group_info->gid[left], tmp)) {
- group_info->gid[right] = group_info->gid[left];
- right = left;
- left -= stride;
- }
- group_info->gid[right] = tmp;
- }
- stride /= 3;
- }
+ sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),
+ gid_cmp, NULL);
}
/* a simple bsearch */
--
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