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Commit 1f3fe7eb authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

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: default avatarMartin 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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6bd3847b

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

kernel/cgroup.c

+35 −0
Original line number Diff line number Diff line
@@ -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.