// SPDX-License-Identifier: GPL-2.0#include <linux/cache.h>#include <linux/sched.h>#include <linux/slab.h>#include <linux/pid_namespace.h>#include "internal.h" /* * /proc/self: */static const char *proc_self_get_link(struct dentry *dentry,				      struct inode *inode,				      struct delayed_call *done){	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);	pid_t tgid = task_tgid_nr_ns(current, ns);	char *name; 	if (!tgid)		return ERR_PTR(-ENOENT);	/* max length of unsigned int in decimal + NULL term */	name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);	if (unlikely(!name))		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);	sprintf(name, "%u", tgid);	set_delayed_call(done, kfree_link, name);	return name;} static const struct inode_operations proc_self_inode_operations = {	.get_link	= proc_self_get_link,}; static unsigned self_inum __ro_after_init; int proc_setup_self(struct super_block *s){	struct inode *root_inode = d_inode(s->s_root);	struct proc_fs_info *fs_info = proc_sb_info(s);	struct dentry *self;	int ret = -ENOMEM; 	inode_lock(root_inode);	self = d_alloc_name(s->s_root, "self");	if (self) {		struct inode *inode = new_inode(s);		if (inode) {			inode->i_ino = self_inum;			inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);			inode->i_mode = S_IFLNK | S_IRWXUGO;			inode->i_uid = GLOBAL_ROOT_UID;			inode->i_gid = GLOBAL_ROOT_GID;			inode->i_op = &proc_self_inode_operations;			d_add(self, inode);			ret = 0;		} else {			dput(self);		}	}	inode_unlock(root_inode); 	if (ret)		pr_err("proc_fill_super: can't allocate /proc/self\n");	else		fs_info->proc_self = self; 	return ret;} void __init proc_self_init(void){	proc_alloc_inum(&self_inum);}