fs/sysfs/sysfs.h

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