From 17703097f3456498e6424614571648c6452f4d34 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 5 Feb 2020 14:26:19 +0100 Subject: 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 Cc: Johannes Weiner Cc: Li Zefan Cc: cgroups@vger.kernel.org Acked-by: Michal Koutný Signed-off-by: Christian Brauner Signed-off-by: Tejun Heo --- 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); -- cgit v1.2.3