>From da1f296fd2bfd5ad3c53d72a1ece593e821cf374 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@xxxxxxxxxx>
Date: Sun, 14 Apr 2013 10:32:19 -0700
While reimplementing cgroup_path(), 65dff759d2 ("cgroup: fix
cgroup_path() vs rename() race") introduced a bug where the path of a
non-root cgroup would have two slahses at the beginning, which is
caused by treating the root cgroup which has the name '/' like
non-root cgroups.
$ grep systemd /proc/self/cgroup
1:name=systemd://user/root/1
Fix it by special casing root cgroup case and not looping over it in
the normal path.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
---
The description was wrong. Updated.
Thanks.
kernel/cgroup.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 678a22c..faf55f5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1811,11 +1811,17 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
int ret = -ENAMETOOLONG;
char *start;
+ if (!cgrp->parent) {
+ if (strlcpy(buf, "/", buflen) >= buflen)
+ return -ENAMETOOLONG;
+ return 0;
+ }
+
start = buf + buflen - 1;
*start = '\0';
rcu_read_lock();
- while (cgrp) {
+ do {
const char *name = cgroup_name(cgrp);
int len;
@@ -1824,15 +1830,12 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
goto out;
memcpy(start, name, len);
- if (!cgrp->parent)
- break;
-
if (--start < buf)
goto out;
*start = '/';
cgrp = cgrp->parent;
- }
+ } while (cgrp->parent);
ret = 0;
memmove(buf, start, buf + buflen - start);
out:
--
1.8.1.4
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