]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blame - kernel/utsname.c
x86, UV: cpu_relax in uv_wait_completion
[mirror_ubuntu-bionic-kernel.git] / kernel / utsname.c
CommitLineData
4865ecf1
SH
1/*
2 * Copyright (C) 2004 IBM Corporation
3 *
4 * Author: Serge Hallyn <serue@us.ibm.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation, version 2 of the
9 * License.
10 */
11
12#include <linux/module.h>
13#include <linux/uts.h>
14#include <linux/utsname.h>
467e9f4b 15#include <linux/err.h>
1aeb272c 16#include <linux/slab.h>
4865ecf1 17
071df104
SH
18/*
19 * Clone a new ns copying an original utsname, setting refcount to 1
20 * @old_ns: namespace to clone
21 * Return NULL on error (failure to kmalloc), new ns otherwise
22 */
23static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
24{
25 struct uts_namespace *ns;
26
27 ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
467e9f4b
CLG
28 if (!ns)
29 return ERR_PTR(-ENOMEM);
30
efc63c4f 31 down_read(&uts_sem);
467e9f4b 32 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
efc63c4f 33 up_read(&uts_sem);
467e9f4b 34 kref_init(&ns->kref);
071df104
SH
35 return ns;
36}
37
4865ecf1
SH
38/*
39 * Copy task tsk's utsname namespace, or clone it if flags
40 * specifies CLONE_NEWUTS. In latter case, changes to the
41 * utsname of this process won't be seen by parent, and vice
42 * versa.
43 */
213dd266 44struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
4865ecf1 45{
071df104 46 struct uts_namespace *new_ns;
4865ecf1 47
e3222c4e 48 BUG_ON(!old_ns);
4865ecf1
SH
49 get_uts_ns(old_ns);
50
071df104 51 if (!(flags & CLONE_NEWUTS))
e3222c4e 52 return old_ns;
071df104
SH
53
54 new_ns = clone_uts_ns(old_ns);
071df104 55
071df104 56 put_uts_ns(old_ns);
e3222c4e 57 return new_ns;
4865ecf1
SH
58}
59
60void free_uts_ns(struct kref *kref)
61{
62 struct uts_namespace *ns;
63
64 ns = container_of(kref, struct uts_namespace, kref);
65 kfree(ns);
66}