linux/fs/sysfs/sysfs.h
Eric W. Biederman 932ea2e374 sysfs: Introduce sysfs_rename_mutex
Looking carefully at the rename code we have a subtle dependency
that the structure of sysfs not change while we are performing
a rename.  If the parent directory of the object we are renaming
changes while the rename is being performed nasty things could
happen when we go to release our locks.

So introduce a sysfs_rename_mutex to prevent this highly
unlikely theoretical issue.

In addition hold sysfs_rename_mutex over all calls to
sysfs_get_dentry. Allowing sysfs_get_dentry to be simplified
in the future.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:51:08 -07:00

120 lines
3.6 KiB
C

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;
atomic_t s_active;
struct sysfs_dirent * s_parent;
struct sysfs_dirent * s_sibling;
struct sysfs_dirent * 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;
unsigned int s_flags;
umode_t s_mode;
ino_t s_ino;
struct dentry * s_dentry;
struct iattr * s_iattr;
atomic_t s_event;
};
#define SD_DEACTIVATED_BIAS INT_MIN
struct sysfs_addrm_cxt {
struct sysfs_dirent *parent_sd;
struct inode *parent_inode;
struct sysfs_dirent *removed;
int cnt;
};
extern struct sysfs_dirent sysfs_root;
extern struct kmem_cache *sysfs_dir_cachep;
extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
extern struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
extern void sysfs_put_active(struct sysfs_dirent *sd);
extern struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
extern void sysfs_put_active_two(struct sysfs_dirent *sd);
extern void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *parent_sd);
extern int sysfs_add_one(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd);
extern void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *sd);
extern void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
extern struct inode * sysfs_get_inode(struct sysfs_dirent *sd);
extern void release_sysfs_dirent(struct sysfs_dirent * sd);
extern struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
extern struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
int type);
extern int sysfs_add_file(struct sysfs_dirent *dir_sd,
const struct attribute *attr, int type);
extern int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name);
extern int sysfs_create_subdir(struct kobject *kobj, const char *name,
struct sysfs_dirent **p_sd);
extern void sysfs_remove_subdir(struct sysfs_dirent *sd);
extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
extern spinlock_t sysfs_assoc_lock;
extern struct mutex sysfs_mutex;
extern struct mutex sysfs_rename_mutex;
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 unsigned int sysfs_type(struct sysfs_dirent *sd)
{
return sd->s_flags & SYSFS_TYPE_MASK;
}
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);
}