static ssize_t depth_write(struct file * file, char const * buf, size_t count, loff_t * offset)
static ssize_t depth_write(struct file * file, char const __user * buf, size_t count, loff_t * offset)
static ssize_t depth_write(struct file * file, char const * buf, size_t count, loff_t * offset){	unsigned long val;	int retval;	if (*offset)		return -EINVAL;	retval = oprofilefs_ulong_from_user(&val, buf, count);	if (retval)		return retval;	retval = oprofile_set_backtrace(val);	if (retval)		return retval;	return count;}