Re: [PATCH net-next v4 06/15] quic: add stream management

[Paolo Abeni <pabeni@redhat.com>]

On 10/29/25 3:35 PM, Xin Long wrote:
+/* Create and register new streams for sending. */
> +static struct quic_stream *quic_stream_send_create(struct quic_stream_table *streams,
> +						   s64 max_stream_id, u8 is_serv)
> +{
> +	struct quic_stream *stream = NULL;
> +	s64 stream_id;
> +
> +	stream_id = streams->send.next_bidi_stream_id;
> +	if (quic_stream_id_uni(max_stream_id))
> +		stream_id = streams->send.next_uni_stream_id;
> +
> +	/* rfc9000#section-2.1: A stream ID that is used out of order results in all streams
> +	 * of that type with lower-numbered stream IDs also being opened.
> +	 */
> +	while (stream_id <= max_stream_id) {
> +		stream = kzalloc(sizeof(*stream), GFP_KERNEL_ACCOUNT);
> +		if (!stream)
> +			return NULL;
> +
> +		stream->id = stream_id;
> +		if (quic_stream_id_uni(stream_id)) {
> +			stream->send.max_bytes = streams->send.max_stream_data_uni;
> +
> +			if (streams->send.next_uni_stream_id < stream_id + QUIC_STREAM_ID_STEP)
> +				streams->send.next_uni_stream_id = stream_id + QUIC_STREAM_ID_STEP;

It's unclear to me the goal the above 2 statements. Dealing with id
wrap-arounds? If 'streams->send.next_uni_stream_id < stream_id +
QUIC_STREAM_ID_STEP' is not true the next quic_stream_send_create() will
reuse the same stream_id.

I moving the above in a separate helper with some comments would help.


> +			streams->send.streams_uni++;
> +
> +			quic_stream_add(streams, stream);
> +			stream_id += QUIC_STREAM_ID_STEP;
> +			continue;
> +		}
> +
> +		if (streams->send.next_bidi_stream_id < stream_id + QUIC_STREAM_ID_STEP)
> +			streams->send.next_bidi_stream_id = stream_id + QUIC_STREAM_ID_STEP;
> +		streams->send.streams_bidi++;
> +
> +		if (quic_stream_id_local(stream_id, is_serv)) {
> +			stream->send.max_bytes = streams->send.max_stream_data_bidi_remote;
> +			stream->recv.max_bytes = streams->recv.max_stream_data_bidi_local;
> +		} else {
> +			stream->send.max_bytes = streams->send.max_stream_data_bidi_local;
> +			stream->recv.max_bytes = streams->recv.max_stream_data_bidi_remote;
> +		}
> +		stream->recv.window = stream->recv.max_bytes;
> +
> +		quic_stream_add(streams, stream);
> +		stream_id += QUIC_STREAM_ID_STEP;
> +	}
> +	return stream;
> +}
> +
> +/* Create and register new streams for receiving. */
> +static struct quic_stream *quic_stream_recv_create(struct quic_stream_table *streams,
> +						   s64 max_stream_id, u8 is_serv)
> +{
> +	struct quic_stream *stream = NULL;
> +	s64 stream_id;
> +
> +	stream_id = streams->recv.next_bidi_stream_id;
> +	if (quic_stream_id_uni(max_stream_id))
> +		stream_id = streams->recv.next_uni_stream_id;
> +
> +	/* rfc9000#section-2.1: A stream ID that is used out of order results in all streams
> +	 * of that type with lower-numbered stream IDs also being opened.
> +	 */
> +	while (stream_id <= max_stream_id) {
> +		stream = kzalloc(sizeof(*stream), GFP_ATOMIC | __GFP_ACCOUNT);
> +		if (!stream)
> +			return NULL;
> +
> +		stream->id = stream_id;
> +		if (quic_stream_id_uni(stream_id)) {
> +			stream->recv.window = streams->recv.max_stream_data_uni;
> +			stream->recv.max_bytes = stream->recv.window;
> +
> +			if (streams->recv.next_uni_stream_id < stream_id + QUIC_STREAM_ID_STEP)
> +				streams->recv.next_uni_stream_id = stream_id + QUIC_STREAM_ID_STEP;
> +			streams->recv.streams_uni++;
> +
> +			quic_stream_add(streams, stream);
> +			stream_id += QUIC_STREAM_ID_STEP;
> +			continue;
> +		}
> +
> +		if (streams->recv.next_bidi_stream_id < stream_id + QUIC_STREAM_ID_STEP)
> +			streams->recv.next_bidi_stream_id = stream_id + QUIC_STREAM_ID_STEP;
> +		streams->recv.streams_bidi++;
> +
> +		if (quic_stream_id_local(stream_id, is_serv)) {
> +			stream->send.max_bytes = streams->send.max_stream_data_bidi_remote;
> +			stream->recv.max_bytes = streams->recv.max_stream_data_bidi_local;
> +		} else {
> +			stream->send.max_bytes = streams->send.max_stream_data_bidi_local;
> +			stream->recv.max_bytes = streams->recv.max_stream_data_bidi_remote;
> +		}
> +		stream->recv.window = stream->recv.max_bytes;
> +
> +		quic_stream_add(streams, stream);
> +		stream_id += QUIC_STREAM_ID_STEP;
> +	}
> +	return stream;
> +}

The above 2 functions has a lot of code in common. I think you could
deduplicate it by:
- defining a named type for quic_stream_table.{send,recv}
- define a generic quic_stream_create() helper using an additonal
argument for the relevant table.{send,recv}
- replace the above 2 functions with a single invocation to such helper.

It looks like there are more de-dup opportunity below.

> +
> +/* Check if a send or receive stream ID is already closed. */
> +static bool quic_stream_id_closed(struct quic_stream_table *streams, s64 stream_id, bool send)
> +{
> +	if (quic_stream_id_uni(stream_id)) {
> +		if (send)
> +			return stream_id < streams->send.next_uni_stream_id;
> +		return stream_id < streams->recv.next_uni_stream_id;
> +	}
> +	if (send)
> +		return stream_id < streams->send.next_bidi_stream_id;
> +	return stream_id < streams->recv.next_bidi_stream_id;
> +}
> +
> +/* Check if a stream ID would exceed local (recv) or peer (send) limits. */
> +bool quic_stream_id_exceeds(struct quic_stream_table *streams, s64 stream_id, bool send)
> +{
> +	u64 nstreams;
> +
> +	if (!send) {
> +		if (quic_stream_id_uni(stream_id))
> +			return stream_id > streams->recv.max_uni_stream_id;
> +		return stream_id > streams->recv.max_bidi_stream_id;
> +	}
> +
> +	if (quic_stream_id_uni(stream_id)) {
> +		if (stream_id > streams->send.max_uni_stream_id)
> +			return true;
> +		stream_id -= streams->send.next_uni_stream_id;
> +		nstreams = quic_stream_id_to_streams(stream_id);
> +		return nstreams + streams->send.streams_uni > streams->send.max_streams_uni;
> +	}
> +
> +	if (stream_id > streams->send.max_bidi_stream_id)
> +		return true;
> +	stream_id -= streams->send.next_bidi_stream_id;
> +	nstreams = quic_stream_id_to_streams(stream_id);
> +	return nstreams + streams->send.streams_bidi > streams->send.max_streams_bidi;
> +}
> +
> +/* Get or create a send stream by ID. */
> +struct quic_stream *quic_stream_send_get(struct quic_stream_table *streams, s64 stream_id,
> +					 u32 flags, bool is_serv)
> +{
> +	struct quic_stream *stream;
> +
> +	if (!quic_stream_id_valid(stream_id, is_serv, true))
> +		return ERR_PTR(-EINVAL);
> +
> +	stream = quic_stream_find(streams, stream_id);
> +	if (stream) {

You should add some comments and possibly lockdep annotation/static
check about the expected locking for the whole stream lifecycle.

/P