1#include <linux/sched.h>
 2#include <linux/slab.h>
 3#include <linux/pid_namespace.h>
 4#include "internal.h"
 5
 6/*
 7 * /proc/thread_self:
 8 */
 9static const char *proc_thread_self_get_link(struct dentry *dentry,
10					     struct inode *inode,
11					     struct delayed_call *done)
12{
13	struct pid_namespace *ns = inode->i_sb->s_fs_info;
14	pid_t tgid = task_tgid_nr_ns(current, ns);
15	pid_t pid = task_pid_nr_ns(current, ns);
16	char *name;
17
18	if (!pid)
19		return ERR_PTR(-ENOENT);
20	name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF,
21				dentry ? GFP_KERNEL : GFP_ATOMIC);
22	if (unlikely(!name))
23		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
24	sprintf(name, "%d/task/%d", tgid, pid);
25	set_delayed_call(done, kfree_link, name);
26	return name;
27}
28
29static const struct inode_operations proc_thread_self_inode_operations = {
30	.get_link	= proc_thread_self_get_link,
31};
32
33static unsigned thread_self_inum;
34
35int proc_setup_thread_self(struct super_block *s)
36{
37	struct inode *root_inode = d_inode(s->s_root);
38	struct pid_namespace *ns = s->s_fs_info;
39	struct dentry *thread_self;
40
41	inode_lock(root_inode);
42	thread_self = d_alloc_name(s->s_root, "thread-self");
43	if (thread_self) {
44		struct inode *inode = new_inode_pseudo(s);
45		if (inode) {
46			inode->i_ino = thread_self_inum;
47			inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
48			inode->i_mode = S_IFLNK | S_IRWXUGO;
49			inode->i_uid = GLOBAL_ROOT_UID;
50			inode->i_gid = GLOBAL_ROOT_GID;
51			inode->i_op = &proc_thread_self_inode_operations;
52			d_add(thread_self, inode);
53		} else {
54			dput(thread_self);
55			thread_self = ERR_PTR(-ENOMEM);
56		}
57	} else {
58		thread_self = ERR_PTR(-ENOMEM);
59	}
60	inode_unlock(root_inode);
61	if (IS_ERR(thread_self)) {
62		pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
63		return PTR_ERR(thread_self);
64	}
65	ns->proc_thread_self = thread_self;
66	return 0;
67}
68
69void __init proc_thread_self_init(void)
70{
71	proc_alloc_inum(&thread_self_inum);
72}