[PATCH -next 1/4] cgroup: Add cgroup_get_from_fd
From: Martin KaFai Lau <hidden>
Date: 2016-06-22 00:23:41
Also in:
cgroups, lkml
Subsystem:
control group (cgroup), the rest · Maintainers:
Tejun Heo, Johannes Weiner, Michal Koutný, Linus Torvalds
Add a helper function to get a cgroup2 from a fd. It will be stored in a bpf array (BPF_MAP_TYPE_CGROUP_ARRAY) which will be introduced in the later patch. Signed-off-by: Martin KaFai Lau <redacted> Cc: Alexei Starovoitov <redacted> Cc: Daniel Borkmann <redacted> Cc: Tejun Heo <redacted> --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a20320c..984f73b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h@@ -87,6 +87,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, struct cgroup_subsys *ss); struct cgroup *cgroup_get_from_path(const char *path); +struct cgroup *cgroup_get_from_fd(int fd); int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 86cb5c6..616c751 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c@@ -62,6 +62,7 @@ #include <linux/proc_ns.h> #include <linux/nsproxy.h> #include <linux/proc_ns.h> +#include <linux/file.h> #include <net/sock.h> /*
@@ -6205,6 +6206,31 @@ struct cgroup *cgroup_get_from_path(const char *path) } 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; + + f = fget_raw(fd); + if (!f) + return NULL; + + css = css_tryget_online_from_dir(f->f_path.dentry, NULL); + fput(f); + if (IS_ERR(css)) + return ERR_CAST(css); + + cgrp = css->cgroup; + if (!cgroup_on_dfl(cgrp)) { + cgroup_put(cgrp); + return ERR_PTR(-EINVAL); + } + + return cgrp; +} +EXPORT_SYMBOL_GPL(cgroup_get_from_fd); + /* * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data * definition in cgroup-defs.h.
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2.5.1