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

[Paolo Abeni <pabeni@redhat.com>]

On 11/6/25 2:27 AM, Xin Long wrote:
> On Tue, Nov 4, 2025 at 6:05 AM Paolo Abeni <pabeni@redhat.com> 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.

A function would be better tacking the next_id value as an argument.
More importantly please document the goal here which is still unclear to me.

>> 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))

Uhmm... with "more de-dup opportunity below" I intended
quic_stream_get_param() and quic_stream_set_param(). I would refrain
from adding macros. I think the above idea ('struct quic_stream_limits')
would not need that?!?

/P