static int snd_compr_write_data(struct snd_compr_stream *stream,
	       const char __user *buf, size_t count)
{
	void *dstn;
	size_t copy;
	struct snd_compr_runtime *runtime = stream->runtime;
	/* 64-bit Modulus */
	u64 app_pointer = div64_u64(runtime->total_bytes_available,
				    runtime->buffer_size);
	app_pointer = runtime->total_bytes_available -
		      (app_pointer * runtime->buffer_size);

	dstn = runtime->buffer + app_pointer;
	pr_debug("copying %ld at %lld\n",
			(unsigned long)count, app_pointer);
	if (count < runtime->buffer_size - app_pointer) {
		if (copy_from_user(dstn, buf, count))
			return -EFAULT;
	} else {
		copy = runtime->buffer_size - app_pointer;
		if (copy_from_user(dstn, buf, copy))
			return -EFAULT;
		if (copy_from_user(runtime->buffer, buf + copy, count - copy))
			return -EFAULT;
	}
	/* if DSP cares, let it know data has been written */
	if (stream->ops->ack)
		stream->ops->ack(stream, count);
	return count;
}

Unknown