* [PATCH] kernel/groups.c: use sort library function
@ 2017-06-12 21:02 Rasmus Villemoes
0 siblings, 0 replies; only message in thread
From: Rasmus Villemoes @ 2017-06-12 21:02 UTC (permalink / raw)
To: Andrew Morton, Matthew Wilcox, Michal Hocko, Rasmus Villemoes
Cc: Alexey Dobriyan, linux-kernel
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.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
kernel/groups.c | 35 +++++++++++------------------------
1 file changed, 11 insertions(+), 24 deletions(-)
diff --git a/kernel/groups.c b/kernel/groups.c
index d09727692a2a..434f6665f187 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 */
--
2.1.4
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