Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / utsname.c
blob8a82b4b8ea52cb3690e25bf039eaf32ff5c8c079
1 /*
2 * Copyright (C) 2004 IBM Corporation
4 * Author: Serge Hallyn <serue@us.ibm.com>
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.
12 #include <linux/module.h>
13 #include <linux/uts.h>
14 #include <linux/utsname.h>
15 #include <linux/err.h>
16 #include <linux/slab.h>
18 static struct uts_namespace *create_uts_ns(void)
20 struct uts_namespace *uts_ns;
22 uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
23 if (uts_ns)
24 kref_init(&uts_ns->kref);
25 return uts_ns;
29 * Clone a new ns copying an original utsname, setting refcount to 1
30 * @old_ns: namespace to clone
31 * Return NULL on error (failure to kmalloc), new ns otherwise
33 static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
35 struct uts_namespace *ns;
37 ns = create_uts_ns();
38 if (!ns)
39 return ERR_PTR(-ENOMEM);
41 down_read(&uts_sem);
42 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
43 up_read(&uts_sem);
44 return ns;
48 * Copy task tsk's utsname namespace, or clone it if flags
49 * specifies CLONE_NEWUTS. In latter case, changes to the
50 * utsname of this process won't be seen by parent, and vice
51 * versa.
53 struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
55 struct uts_namespace *new_ns;
57 BUG_ON(!old_ns);
58 get_uts_ns(old_ns);
60 if (!(flags & CLONE_NEWUTS))
61 return old_ns;
63 new_ns = clone_uts_ns(old_ns);
65 put_uts_ns(old_ns);
66 return new_ns;
69 void free_uts_ns(struct kref *kref)
71 struct uts_namespace *ns;
73 ns = container_of(kref, struct uts_namespace, kref);
74 kfree(ns);