cgroup: fix and restructure error handling in copy_cgroup_ns()

copy_cgroup_ns()'s error handling was broken and the attempt to fix it
d22025570e2e ("cgroup: fix alloc_cgroup_ns() error handling in
copy_cgroup_ns()") was broken too in that it ended up trying an
ERR_PTR() value.

There's only one place where copy_cgroup_ns() needs to perform cleanup
after failure.  Simplify and fix the error handling by removing the
goto's.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d92d91a..2c88149 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -6058,9 +6058,8 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
                                        struct user_namespace *user_ns,
                                        struct cgroup_namespace *old_ns)
 {
-       struct cgroup_namespace *new_ns = NULL;
-       struct css_set *cset = NULL;
-       int err;
+       struct cgroup_namespace *new_ns;
+       struct css_set *cset;
 
        BUG_ON(!old_ns);
 
@@ -6070,9 +6069,8 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
        }
 
        /* Allow only sysadmin to create cgroup namespace. */
-       err = -EPERM;
        if (!ns_capable(user_ns, CAP_SYS_ADMIN))
-               goto err_out;
+               return ERR_PTR(-EPERM);
 
        mutex_lock(&cgroup_mutex);
        spin_lock_bh(&css_set_lock);
@@ -6085,20 +6083,14 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
 
        new_ns = alloc_cgroup_ns();
        if (IS_ERR(new_ns)) {
-               err = PTR_ERR(new_ns);
-               goto err_out;
+               put_css_set(cset);
+               return new_ns;
        }
 
        new_ns->user_ns = get_user_ns(user_ns);
        new_ns->root_cset = cset;
 
        return new_ns;
-
-err_out:
-       if (cset)
-               put_css_set(cset);
-       kfree(new_ns);
-       return ERR_PTR(err);
 }
 
 static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)