1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
struct sysfs_elem_dir {
struct kobject * kobj;
};
struct sysfs_elem_symlink {
struct sysfs_dirent * target_sd;
};
struct sysfs_elem_attr {
struct attribute * attr;
};
struct sysfs_elem_bin_attr {
struct bin_attribute * bin_attr;
};
/*
* As long as s_count reference is held, the sysfs_dirent itself is
* accessible. Dereferencing s_elem or any other outer entity
* requires s_active reference.
*/
struct sysfs_dirent {
atomic_t s_count;
struct rw_semaphore s_active;
struct sysfs_dirent * s_parent;
struct list_head s_sibling;
struct list_head s_children;
const char * s_name;
union {
struct sysfs_elem_dir dir;
struct sysfs_elem_symlink symlink;
struct sysfs_elem_attr attr;
struct sysfs_elem_bin_attr bin_attr;
} s_elem;
int s_type;
umode_t s_mode;
ino_t s_ino;
struct dentry * s_dentry;
struct iattr * s_iattr;
atomic_t s_event;
};
/*
* A sysfs file which deletes another file when written to need to
* write lock the s_active of the victim while its s_active is read
* locked for the write operation. Tell lockdep that this is okay.
*/
enum sysfs_s_active_class
{
SYSFS_S_ACTIVE_NORMAL, /* file r/w access, etc - default */
SYSFS_S_ACTIVE_DEACTIVATE, /* file deactivation */
};
extern struct vfsmount * sysfs_mount;
extern struct kmem_cache *sysfs_dir_cachep;
extern void sysfs_delete_inode(struct inode *inode);
extern void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode);
extern struct inode * sysfs_new_inode(struct sysfs_dirent *sd);
extern void sysfs_instantiate(struct dentry *dentry, struct inode *inode);
extern void release_sysfs_dirent(struct sysfs_dirent * sd);
extern int sysfs_dirent_exist(struct sysfs_dirent *, const unsigned char *);
extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
int type);
extern void sysfs_attach_dirent(struct sysfs_dirent *sd,
struct sysfs_dirent *parent_sd,
struct dentry *dentry);
extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
extern int sysfs_hash_and_remove(struct dentry * dir, const char * name);
extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name);
extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);
extern void sysfs_remove_subdir(struct dentry *);
extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
extern spinlock_t sysfs_lock;
extern spinlock_t kobj_sysfs_assoc_lock;
extern struct rw_semaphore sysfs_rename_sem;
extern struct super_block * sysfs_sb;
extern const struct file_operations sysfs_dir_operations;
extern const struct file_operations sysfs_file_operations;
extern const struct file_operations bin_fops;
extern const struct inode_operations sysfs_dir_inode_operations;
extern const struct inode_operations sysfs_symlink_inode_operations;
static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
{
if (sd) {
WARN_ON(!atomic_read(&sd->s_count));
atomic_inc(&sd->s_count);
}
return sd;
}
static inline void sysfs_put(struct sysfs_dirent * sd)
{
if (sd && atomic_dec_and_test(&sd->s_count))
release_sysfs_dirent(sd);
}
/**
* sysfs_get_active - get an active reference to sysfs_dirent
* @sd: sysfs_dirent to get an active reference to
*
* Get an active reference of @sd. This function is noop if @sd
* is NULL.
*
* RETURNS:
* Pointer to @sd on success, NULL on failure.
*/
static inline struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
{
if (sd) {
if (unlikely(!down_read_trylock(&sd->s_active)))
sd = NULL;
}
return sd;
}
/**
* sysfs_put_active - put an active reference to sysfs_dirent
* @sd: sysfs_dirent to put an active reference to
*
* Put an active reference to @sd. This function is noop if @sd
* is NULL.
*/
static inline void sysfs_put_active(struct sysfs_dirent *sd)
{
if (sd)
up_read(&sd->s_active);
}
/**
* sysfs_get_active_two - get active references to sysfs_dirent and parent
* @sd: sysfs_dirent of interest
*
* Get active reference to @sd and its parent. Parent's active
* reference is grabbed first. This function is noop if @sd is
* NULL.
*
* RETURNS:
* Pointer to @sd on success, NULL on failure.
*/
static inline struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
{
if (sd) {
if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
return NULL;
if (unlikely(!sysfs_get_active(sd))) {
sysfs_put_active(sd->s_parent);
return NULL;
}
}
return sd;
}
/**
* sysfs_put_active_two - put active references to sysfs_dirent and parent
* @sd: sysfs_dirent of interest
*
* Put active references to @sd and its parent. This function is
* noop if @sd is NULL.
*/
static inline void sysfs_put_active_two(struct sysfs_dirent *sd)
{
if (sd) {
sysfs_put_active(sd);
sysfs_put_active(sd->s_parent);
}
}
/**
* sysfs_deactivate - deactivate sysfs_dirent
* @sd: sysfs_dirent to deactivate
*
* Deny new active references and drain existing ones. s_active
* will be unlocked when the sysfs_dirent is released.
*/
static inline void sysfs_deactivate(struct sysfs_dirent *sd)
{
down_write_nested(&sd->s_active, SYSFS_S_ACTIVE_DEACTIVATE);
/* s_active will be unlocked by the thread doing the final put
* on @sd. Lie to lockdep.
*/
rwsem_release(&sd->s_active.dep_map, 1, _RET_IP_);
}
static inline int sysfs_is_shadowed_inode(struct inode *inode)
{
return S_ISDIR(inode->i_mode) && inode->i_op->follow_link;
}
|
