-/* Sysfs attribute files are pollable. The idea is that you read
- * the content and then you use 'poll' or 'select' to wait for
- * the content to change. When the content changes (assuming the
- * manager for the kobject supports notification), poll will
- * return POLLERR|POLLPRI, and select will return the fd whether
- * it is waiting for read, write, or exceptions.
- * Once poll/select indicates that the value has changed, you
- * need to close and re-open the file, as simply seeking and reading
- * again will not get new data, or reset the state of 'poll'.
- * Reminder: this only works for attributes which actively support
- * it, and it is not possible to test an attribute from userspace
- * to see if it supports poll (Nether 'poll' or 'select' return
- * an appropriate error code). When in doubt, set a suitable timeout value.
- */
-static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
-{
- struct sysfs_buffer * buffer = filp->private_data;
- struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
- struct sysfs_dirent * sd = filp->f_dentry->d_fsdata;
- int res = 0;
-
- poll_wait(filp, &kobj->poll, wait);
-
- if (buffer->event != atomic_read(&sd->s_event)) {
- res = POLLERR|POLLPRI;
- buffer->needs_read_fill = 1;
- }
-
- return res;
-}
-
-
-static struct dentry *step_down(struct dentry *dir, const char * name)
-{
- struct dentry * de;
-
- if (dir == NULL || dir->d_inode == NULL)
- return NULL;
-
- mutex_lock(&dir->d_inode->i_mutex);
- de = lookup_one_len(name, dir, strlen(name));
- mutex_unlock(&dir->d_inode->i_mutex);
- dput(dir);
- if (IS_ERR(de))
- return NULL;
- if (de->d_inode == NULL) {
- dput(de);
- return NULL;
- }
- return de;
-}
-
-void sysfs_notify(struct kobject * k, char *dir, char *attr)
-{
- struct dentry *de = k->dentry;
- if (de)
- dget(de);
- if (de && dir)
- de = step_down(de, dir);
- if (de && attr)
- de = step_down(de, attr);
- if (de) {
- struct sysfs_dirent * sd = de->d_fsdata;
- if (sd)
- atomic_inc(&sd->s_event);
- wake_up_interruptible(&k->poll);
- dput(de);
- }
-}
-EXPORT_SYMBOL_GPL(sysfs_notify);
-
-const struct file_operations sysfs_file_operations = {