From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1731-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 1DF6F986428 for ; Wed, 3 Mar 2021 16:52:59 +0000 (UTC) Date: Wed, 3 Mar 2021 11:52:43 -0500 From: "Michael S. Tsirkin" Message-ID: <20210303114831-mutt-send-email-mst@kernel.org> References: <20210218060715.1075547-1-arseny.krasnov@kaspersky.com> <20210218060827.1075863-1-arseny.krasnov@kaspersky.com> <20210224093200.tpflaqgoap4fe5ax@steredhat> <20210303130843.6b457503.cohuck@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210303130843.6b457503.cohuck@redhat.com> Subject: Re: [virtio-comment] [RFC PATCH v1 1/1] virtio-vsock: add SOCK_SEQPACKET description Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: Cornelia Huck Cc: Stefano Garzarella , Arseny Krasnov , virtio-comment@lists.oasis-open.org, Stefan Hajnoczi , Jason Wang , "David S. Miller" , Jakub Kicinski , Jorgen Hansen , Andra Paraschiv , Norbert Slusarek , Colin Ian King , virtualization@lists.linux-foundation.org, oxffffaa@gmail.com List-ID: On Wed, Mar 03, 2021 at 01:08:43PM +0100, Cornelia Huck wrote: > On Wed, 24 Feb 2021 10:32:00 +0100 > Stefano Garzarella wrote: > > > On Thu, Feb 18, 2021 at 09:08:23AM +0300, Arseny Krasnov wrote: > > >Signed-off-by: Arseny Krasnov > > >--- > > > virtio-vsock.tex | 40 +++++++++++++++++++++++++++++++++++++--- > > > 1 file changed, 37 insertions(+), 3 deletions(-) > > > > > >diff --git a/virtio-vsock.tex b/virtio-vsock.tex > > >index da7e641..1ee8f99 100644 > > >--- a/virtio-vsock.tex > > >+++ b/virtio-vsock.tex > > >@@ -102,6 +102,11 @@ \subsection{Device Operation}\label{sec:Device Types / Socket Device / Device Op > > > VIRTIO_VSOCK_OP_CREDIT_UPDATE = 6, > > > /* Request the peer to send the credit info to us */ > > > VIRTIO_VSOCK_OP_CREDIT_REQUEST = 7, > > >+ > > >+ /* Message begin for SOCK_SEQPACKET */ > > >+ VIRTIO_VSOCK_OP_SEQ_BEGIN = 8, > > >+ /* Message end for SOCK_SEQPACKET */ > > >+ VIRTIO_VSOCK_OP_SEQ_END = 9, > > > }; > > > \end{lstlisting} > > > > > >@@ -140,11 +145,11 @@ \subsubsection{Addressing}\label{sec:Device Types / Socket Device / Device Opera > > > consists of a (cid, port number) tuple. The header fields used for this are > > > \field{src_cid}, \field{src_port}, \field{dst_cid}, and \field{dst_port}. > > > > > >-Currently only stream sockets are supported. \field{type} is 1 for stream > > >-socket types. > > >+Currently stream and seqpacket sockets are supported. \field{type} is 1 for > > >+stream socket types. \field{type} is 2 for seqpacket socket types. > > > > > > Stream sockets provide in-order, guaranteed, connection-oriented delivery > > >-without message boundaries. > > >+without message boundaries. Seqpacket sockets also provide message boundaries. > > > > > > \subsubsection{Buffer Space Management}\label{sec:Device Types / Socket Device / Device Operation / Buffer Space Management} > > > \field{buf_alloc} and \field{fwd_cnt} are used for buffer space management of > > >@@ -240,6 +245,35 @@ \subsubsection{Stream Sockets}\label{sec:Device Types / Socket Device / Device O > > > destination) address tuple for a new connection while the other peer is still > > > processing the old connection. > > > > > >+\subsubsection{Seqpacket Sockets}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets} > > >+ > > >+Seqpacket sockets differ from stream sockets only in data transmission way: in > > >+stream sockets all data is sent using only VIRTIO_VSOCK_OP_RW packets. In > > >+seqpacket sockets, to provide message boundaries, every sequence of > > >+VIRTIO_VSOCK_OP_RW packets of each message is headed with > > ^ > > Since this is a spec, I think we should use MUST when something must be > > respected by the peer, for example here we can say "MUST be headed" > > > > >+VIRTIO_VSOCK_OP_SEQ_BEGIN and tailed with VIRTIO_VSOCK_OP_SEQ_END packets. > > >+Both VIRTIO_VSOCK_OP_SEQ_BEGIN and VIRTIO_VSOCK_OP_SEQ_END packets carry > > ^ > > Same here "MUST carry" and in the rest of the patch. > > Actually, MUST and friends are really for normative sections; I'd > advise to have a description of how this feature works and then some > device/driver normative clauses with MUST statements (like "the device > MUST reject " or so). I agree we do want normative sections but please don't add MUST etc elsewhere. Also vague text saying "malformed" isn't all that helpful if it's a MUST. How does driver know for sure it's malformed? easy to miss some requirement. Therefore easiest thing it just to do some copy-pasting. E.g. You start with above and add a normative section saying: Driver MUST use XYZ in VIRTIO_VSOCK_OP_SEQ_END packets. We typically don't specify behaviour when out of spec, if we should here then please make a separate chapter for this explaining the how and the why. -- MST This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. 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