[PATCH] cgroup: simplify cleanup in cgroup_css_set_fork()

[PATCH] cgroup: simplify cleanup in cgroup_css_set_fork()

[Christian Brauner]

The call that initializes kargs->cset is find_css_set() and it is the
last call in cgroup_css_set_fork(). If find_css_set() fails kargs->cset
is NULL and we go to the cleanup path where we check that kargs->cset is
non-NULL and if it is we call put_css_set(kargs->cset). But it'll always
be NULL so put_css_set(kargs->cset) is never hit. Remove it.

Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
Reported-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/cgroup/cgroup.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index ffaccd6373f1..2ba516205057 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6247,8 +6247,6 @@ static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
 	if (dst_cgrp)
 		cgroup_put(dst_cgrp);
 	put_css_set(cset);
-	if (kargs->cset)
-		put_css_set(kargs->cset);
 	return ret;
 }
 

base-commit: 1c23f9e627a7b412978b4e852793c5e3c3efc555
-- 
2.34.1

Re: [PATCH] cgroup: simplify cleanup in cgroup_css_set_fork()

[Michal Koutný]

Hello.

On Tue, Aug 23, 2022 at 11:11:47AM +0200, Christian Brauner <brauner-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>  kernel/cgroup/cgroup.c | 2 --
>  1 file changed, 2 deletions(-)

Sensible cleanup,
Reviewed-by: Michal Koutný <mkoutny-IBi9RG/b67k@public.gmane.org>

Re: [PATCH] cgroup: simplify cleanup in cgroup_css_set_fork()

[Mukesh Ojha]

Hi,

On 8/23/2022 2:41 PM, Christian Brauner wrote:
> The call that initializes kargs->cset is find_css_set() and it is the
> last call in cgroup_css_set_fork(). If find_css_set() fails kargs->cset
> is NULL and we go to the cleanup path where we check that kargs->cset is
> non-NULL and if it is we call put_css_set(kargs->cset). But it'll always
> be NULL so put_css_set(kargs->cset) is never hit. Remove it.
> 
> Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
> Reported-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> Signed-off-by: Christian Brauner (Microsoft) <brauner-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> ---
>   kernel/cgroup/cgroup.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index ffaccd6373f1..2ba516205057 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -6247,8 +6247,6 @@ static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
>   	if (dst_cgrp)
>   		cgroup_put(dst_cgrp);
>   	put_css_set(cset);
> -	if (kargs->cset)
> -		put_css_set(kargs->cset);
>   	return ret;
>   }
>   

LGTM.

Reviewed-by: Mukesh Ojha <quic_mojha-jfJNa2p1gH1BDgjK7y7TUQ@public.gmane.org>

-Mukesh

> 
> base-commit: 1c23f9e627a7b412978b4e852793c5e3c3efc555