On 2013/4/15 1:37, Tejun Heo wrote:
>>From 277f3d4be79aefe2071d9053a9c7c89c4e5dad30 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 adding '/' before the name of the root cgroup which is an
> empty string.
>
I guess I booted a wrong kernel when testing that patch...
> $ grep systemd /proc/self/cgroup
> 1:name=systemd://user/root/1
>
> Fix it by special casing root cgroup.
>
I made a patch to fix it before the weekend, but didn't post it. It doesn't
treat root-only cgroup specially.
You can apply whichever you like better.
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Li Zefan <lizefan@xxxxxxxxxx>
> ---
> Applying to cgroup/for-3.10.
>
> Thanks.
>
> kernel/cgroup.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
[PATCH] cgroup: make cgroup_path() not print double slashes
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.
Fix it by not adding '/' if it's the root cgroup.
$ grep systemd /proc/self/cgroup
1:name=systemd://user/root/1
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
---
kernel/cgroup.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 06aeb42..2a28425 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1809,14 +1809,15 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
goto out;
memcpy(start, name, len);
- if (!cgrp->parent)
+ cgrp = cgrp->parent;
+ if (!cgrp)
break;
+ if (!cgrp->parent)
+ continue;
if (--start < buf)
goto out;
*start = '/';
-
- cgrp = cgrp->parent;
}
ret = 0;
memmove(buf, start, buf + buflen - start);
--
1.8.0.2
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