Driver core: fix race in sysfs between sysfs_remove_file() and read()/write()
[linux-2.6.git] / fs / sysfs / group.c
1 /*
2  * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
3  *
4  * Copyright (c) 2003 Patrick Mochel
5  * Copyright (c) 2003 Open Source Development Lab
6  *
7  * This file is released undert the GPL v2. 
8  *
9  */
10
11 #include <linux/kobject.h>
12 #include <linux/module.h>
13 #include <linux/dcache.h>
14 #include <linux/namei.h>
15 #include <linux/err.h>
16 #include <asm/semaphore.h>
17 #include "sysfs.h"
18
19
20 static void remove_files(struct dentry * dir, 
21                          const struct attribute_group * grp)
22 {
23         struct attribute *const* attr;
24
25         for (attr = grp->attrs; *attr; attr++)
26                 sysfs_hash_and_remove(dir,(*attr)->name);
27 }
28
29 static int create_files(struct dentry * dir,
30                         const struct attribute_group * grp)
31 {
32         struct attribute *const* attr;
33         int error = 0;
34
35         for (attr = grp->attrs; *attr && !error; attr++) {
36                 error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
37         }
38         if (error)
39                 remove_files(dir,grp);
40         return error;
41 }
42
43
44 int sysfs_create_group(struct kobject * kobj, 
45                        const struct attribute_group * grp)
46 {
47         struct dentry * dir;
48         int error;
49
50         BUG_ON(!kobj || !kobj->dentry);
51
52         if (grp->name) {
53                 error = sysfs_create_subdir(kobj,grp->name,&dir);
54                 if (error)
55                         return error;
56         } else
57                 dir = kobj->dentry;
58         dir = dget(dir);
59         if ((error = create_files(dir,grp))) {
60                 if (grp->name)
61                         sysfs_remove_subdir(dir);
62         }
63         dput(dir);
64         return error;
65 }
66
67 void sysfs_remove_group(struct kobject * kobj, 
68                         const struct attribute_group * grp)
69 {
70         struct dentry * dir;
71
72         if (grp->name)
73                 dir = lookup_one_len(grp->name, kobj->dentry,
74                                 strlen(grp->name));
75         else
76                 dir = dget(kobj->dentry);
77
78         remove_files(dir,grp);
79         if (grp->name)
80                 sysfs_remove_subdir(dir);
81         /* release the ref. taken in this routine */
82         dput(dir);
83 }
84
85
86 EXPORT_SYMBOL_GPL(sysfs_create_group);
87 EXPORT_SYMBOL_GPL(sysfs_remove_group);