Re: [PATCH 3/8] man/man7/unix.7: SIOCINQ: Document behavior for SOCK_SEQPACKET

[Kuniyuki Iwashima <kuniyu@google.com>]

On Wed, 21 Oct 2026 23:07:55 +0200, Günther Noack wrote:
> Document the SIOCINQ behavior for SOCK_SEQPACKET,
> which sums up the lengths of all messages in the receive queue.
> 
> Restructure sentence order, so that socket type differences are
> discussed in on paragraph, and commonalities in the next.
> 
> For reference, the SIOCINQ lookup is implemented in
> unix_inq_len() in linux.git net/unix/af_unix.c.
> 
> This function first rejects SIOCINQ for listening sockets with
> -EINVAL, then does a case analysis for the three types of Unix Domain
> Sockets:
> 
> For SOCK_STREAM, the result is:
> 
> 	return READ_ONCE(unix_sk(sk)->inq_len);
> 
> For SOCK_SEQPACKET, the result is calculated using:
> 
> 	skb_queue_walk(&sk->sk_receive_queue, skb)
>         	amount += unix_skb_len(skb);
> 
> For SOCK_DGRAM, the result is:
> 
> 	skb = skb_peek(&sk->sk_receive_queue);
> 	if (skb)
> 		amount = skb->len;
> 
> Cc: Kuniyuki Iwashima <kuniyu@google.com>
> Assisted-by: LLM
> Signed-off-by: Günther Noack <gnoack3000@gmail.com>
> ---
> 
> Notes:
>     I double checked this all in the code, and quoted the code.  Both the
>     commit message and commit body were substantially edited based on the
>     initial LLM-based version.  (Nevertheless, I would have likely missed
>     the inaccuracy if the LLM hadn't found it.)
>     
>     The LLM initially just slapped an additional sentence into the
>     paragraph, but that was mixing the socket-type-specific concerns with
>     the general description -- I split that paragraph apart so that we
>     have one paragraph for the three socket types and one for the
>     socket-type-independent description.
> 
>  man/man7/unix.7 | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/man/man7/unix.7 b/man/man7/unix.7
> index d0c1765dfd79..4c46b54206a5 100644
> --- a/man/man7/unix.7
> +++ b/man/man7/unix.7
> @@ -606,6 +606,19 @@ can be:
>  For
>  .B SOCK_STREAM

and SOCK_SEQPACKET

>  sockets, this call returns the number of unread bytes in the receive buffer.
> +For
> +.B SOCK_DGRAM
> +sockets,
> +the returned value is the same as
> +for Internet domain datagram sockets;
> +see
> +.BR udp (7).

Simply say it's the length of the first datagram.
so that we don't need to jump to udp doc.


> +For
> +.B SOCK_SEQPACKET
> +sockets,
> +this call returns the total number of bytes
> +in all messages queued in the receive buffer.
> +.IP
>  The socket must not be in LISTEN state, otherwise an error
>  .RB ( EINVAL )
>  is returned.
> @@ -625,13 +638,6 @@ defined in
>  .\" That number is normally larger than the number of bytes of pending
>  .\" output.  Since this info is, from userland's point of view, imprecise,
>  .\" and it may well change, probably best not to document this now.
> -For
> -.B SOCK_DGRAM
> -sockets,
> -the returned value is the same as
> -for Internet domain datagram sockets;
> -see
> -.BR udp (7).
>  .SH ERRORS
>  .TP
>  .B EADDRINUSE
> -- 
> 2.56.0
>