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authorMartin KaFai Lau <kafai@fb.com>2016-06-30 10:28:42 -0700
committerDavid S. Miller <davem@davemloft.net>2016-07-01 16:30:38 -0400
commit1f3fe7ebf6136c341012db9f554d4caa566fcbaa (patch)
treeec78d296ec21640777ed39c1277fa7b5b88e4169
parent6bd3847bdc3ba97e642cb9af9d16b0f056da31a2 (diff)
downloadlinux-1f3fe7ebf6136c341012db9f554d4caa566fcbaa.tar.bz2
cgroup: Add cgroup_get_from_fd
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 <kafai@fb.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/cgroup.h1
-rw-r--r--kernel/cgroup.c35
2 files changed, 36 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a20320c666fd..984f73b719a9 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 75c0ff00aca6..50787cd61da2 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>
/*
@@ -6209,6 +6210,40 @@ struct cgroup *cgroup_get_from_path(const char *path)
}
EXPORT_SYMBOL_GPL(cgroup_get_from_path);
+/**
+ * cgroup_get_from_fd - get a cgroup pointer from a fd
+ * @fd: fd obtained by open(cgroup2_dir)
+ *
+ * Find the cgroup from a fd which should be obtained
+ * by opening a cgroup directory. Returns a pointer to the
+ * cgroup on success. ERR_PTR is returned if the cgroup
+ * cannot be found.
+ */
+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 ERR_PTR(-EBADF);
+
+ 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(-EBADF);
+ }
+
+ 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.