Message-ID: <CADvbK_cJxGaam4gLCBg0EpNRWfAVyOTLZmD09LB=okWKr3prew@mail.gmail.com>
Date: Thu, 6 Nov 2025 11:22:28 -0500
From: Xin Long <lucien.xin@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: network dev <netdev@...r.kernel.org>, quic@...ts.linux.dev, davem@...emloft.net, 
	kuba@...nel.org, Eric Dumazet <edumazet@...gle.com>, Simon Horman <horms@...nel.org>, 
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	Paulo Alcantara <pc@...guebit.com>, Tom Talpey <tom@...pey.com>, kernel-tls-handshake@...ts.linux.dev, 
	Chuck Lever <chuck.lever@...cle.com>, Jeff Layton <jlayton@...nel.org>, 
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	Andy Gospodarek <andrew.gospodarek@...adcom.com>
Subject: Re: [PATCH net-next v4 06/15] quic: add stream management

On Thu, Nov 6, 2025 at 3:52 AM Paolo Abeni <pabeni@...hat.com> wrote:
>
> On 11/6/25 2:27 AM, Xin Long wrote:
> > On Tue, Nov 4, 2025 at 6:05 AM Paolo Abeni <pabeni@...hat.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 if check may not be needed, I will double confirm:
if (limits->next_uni_stream_id < stream_id + QUIC_STREAM_ID_STEP)

If it's just one line below, maybe I just add a comment like in here?

/* Streams must be opened sequentially. Update the next stream ID so the
 * correct starting point is known if an out-of-order open is requested.
 */
limits->next_uni_stream_id = stream_id + QUIC_STREAM_ID_STEP;

> >> 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?!?
>
Ah okay, that makes sense now, I don't like such macros either.
The above idea won't involve any new macros.

Thanks.

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