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

On Tue, Nov 4, 2025 at 6:05 AM Paolo Abeni <[email protected]> wrote:
>
> 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.
>
I will add a macro for this:

#define quic_stream_id_next_update(limits, type, id)    \
do {                                                    \
        if ((limits)->next_##type##_stream_id < (id) +
QUIC_STREAM_ID_STEP)     \
                (limits)->next_##type##_stream_id = (id) +
QUIC_STREAM_ID_STEP; \
        (limits)->streams_##type++;
         \
} while (0)

So that we can use it to update both next_uni_stream_id and next_bidi_stream_id.

>
> > +                     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 /() helper using an additonal
> argument for the relevant table.{send,recv}
> - replace the above 2 functions with a single invocation to such helper.
This is a very smart idea!

It will dedup not only quic_stream_recv_create(), but also
quic_stream_get_param() and quic_stream_set_param().

I will define a type named 'struct quic_stream_limits'.
Note that, since we must pass 'bool send' to quic_stream_create() for
setting the fields in a single 'stream' .

        if (quic_stream_id_uni(stream_id)) {
                if (send) {
                        stream->send.max_bytes = limits->max_stream_data_uni;
                } else {
                        stream->recv.max_bytes = limits->max_stream_data_uni;
                        stream->recv.window = stream->recv.max_bytes;
                }

I'm planning not to pass additional argument of table.{send,recv},
but do this in quic_stream_create():
        struct quic_stream_limits *limits = &streams->send;
        gfp_t gfp = GFP_KERNEL_ACCOUNT;

        if (!send) {
                limits = &streams->recv;
                gfp = GFP_ATOMIC | __GFP_ACCOUNT;
        }

>
> It looks like there are more de-dup opportunity below.
>
Yes, the difference is only the variable name _uni_ and _bidi_.
I'm planning to de-dup them with macros like:

#define quic_stream_id_below_next(streams, type, id, send)        \
    ((send) ? ((id) < (streams)->send.next_##type##_stream_id) :    \
          ((id) < (streams)->recv.next_##type##_stream_id))

/* 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))
        return quic_stream_id_below_next(streams, uni, stream_id, send);
    return quic_stream_id_below_next(streams, bidi, stream_id, send);
}

#define quic_stream_id_above_max(streams, type, id)            \
    (((id) > (streams)->send.max_##type##_stream_id) ? true :    \
        (quic_stream_id_to_streams((id) -
(streams)->send.next_##type##_stream_id) +    \
            (streams)->send.streams_##type >
(streams)->send.max_streams_##type))

/* 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)
{
    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))
        return quic_stream_id_above_max(streams, uni, stream_id);
    return quic_stream_id_above_max(streams, bidi, stream_id);
}

Do you think it's worth it?

> > +
> > +/* 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.
>
sk is not seen in this file, so I will add some comments to describe this
will also be called under the sock lock.

Thanks.