参照元

説明

引数

返り値

参考

実装

/*
 * Lightweight file lookup - no refcnt increment if fd table isn't shared. 
 * You can use this only if it is guranteed that the current task already 
 * holds a refcnt to that file. That check has to be done at fget() only
 * and a flag is returned to be passed to the corresponding fput_light().
 * There must not be a cloning between an fget_light/fput_light pair.
 */
struct file *fget_light(unsigned int fd, int *fput_needed)
{
	struct file *file;
	struct files_struct *files = current->files;
	*fput_needed = 0;
	if (likely((atomic_read(&files->count) == 1))) {
		file = fcheck_files(files, fd);
	} else {
		rcu_read_lock();
		file = fcheck_files(files, fd);
		if (file) {
			if (atomic_long_inc_not_zero(&file->f_count))
				*fput_needed = 1;
			else
				/* Didn't get the reference, someone's freed */
				file = NULL;
		}
		rcu_read_unlock();
	}

	return file;
}

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Last-modified: 2014-09-13 (土) 08:26:41