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authorChristian Brauner <christian.brauner@ubuntu.com>2020-02-05 14:26:19 +0100
committerTejun Heo <tj@kernel.org>2020-02-12 17:57:51 -0500
commit17703097f3456498e6424614571648c6452f4d34 (patch)
treef302a8825f3e6bc554d92a19b6e89c49b00cd2ed /kernel/cgroup
parent6df970e4f5d2c273554550d40d8b92cea9bec1a0 (diff)
cgroup: add cgroup_get_from_file() helper
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>
Diffstat (limited to 'kernel/cgroup')
-rw-r--r--kernel/cgroup/cgroup.c30
1 files changed, 19 insertions, 11 deletions
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);