From 17703097f3456498e6424614571648c6452f4d34 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Wed, 5 Feb 2020 14:26:19 +0100
Subject: cgroup: add cgroup_get_from_file() helper
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Add a helper cgroup_get_from_file(). The helper will be used in
subsequent patches to retrieve a cgroup while holding a reference to the
struct file it was taken from.
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: cgroups@vger.kernel.org
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/cgroup/cgroup.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
(limited to 'kernel/cgroup')
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 9ca51bf3769a..16fe1c6cad35 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5880,6 +5880,24 @@ void cgroup_fork(struct task_struct *child)
INIT_LIST_HEAD(&child->cg_list);
}
+static struct cgroup *cgroup_get_from_file(struct file *f)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *cgrp;
+
+ css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
+ if (IS_ERR(css))
+ return ERR_CAST(css);
+
+ cgrp = css->cgroup;
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+
+ return cgrp;
+}
+
/**
* cgroup_can_fork - called on a new task before the process is exposed
* @child: the task in question.
@@ -6171,7 +6189,6 @@ EXPORT_SYMBOL_GPL(cgroup_get_from_path);
*/
struct cgroup *cgroup_get_from_fd(int fd)
{
- struct cgroup_subsys_state *css;
struct cgroup *cgrp;
struct file *f;
@@ -6179,17 +6196,8 @@ struct cgroup *cgroup_get_from_fd(int fd)
if (!f)
return ERR_PTR(-EBADF);
- css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
+ cgrp = cgroup_get_from_file(f);
fput(f);
- if (IS_ERR(css))
- return ERR_CAST(css);
-
- cgrp = css->cgroup;
- if (!cgroup_on_dfl(cgrp)) {
- cgroup_put(cgrp);
- return ERR_PTR(-EBADF);
- }
-
return cgrp;
}
EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
--
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