Netdev Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Stefano Garzarella <sgarzare@redhat.com>
To: Arseny Krasnov <arseny.krasnov@kaspersky.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Colin Ian King <colin.king@canonical.com>,
	Andra Paraschiv <andraprs@amazon.com>,
	Norbert Slusarek <nslusarek@gmx.net>,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	oxffffaa@gmail.com
Subject: Re: [RFC PATCH v1 0/7] virtio/vsock: introduce MSG_EOR flag for SEQPACKET
Date: Wed, 4 Aug 2021 14:57:37 +0200	[thread overview]
Message-ID: <20210804125737.kbgc6mg2v5lw25wu@steredhat> (raw)
In-Reply-To: <20210726163137.2589102-1-arseny.krasnov@kaspersky.com>

Hi Arseny,

On Mon, Jul 26, 2021 at 07:31:33PM +0300, Arseny Krasnov wrote:
>	This patchset implements support of MSG_EOR bit for SEQPACKET
>AF_VSOCK sockets over virtio transport.
>	Idea is to distinguish concepts of 'messages' and 'records'.
>Message is result of sending calls: 'write()', 'send()', 'sendmsg()'
>etc. It has fixed maximum length, and it bounds are visible using
>return from receive calls: 'read()', 'recv()', 'recvmsg()' etc.
>Current implementation based on message definition above.

Okay, so the implementation we merged is wrong right?
Should we disable the feature bit in stable kernels that contain it? Or 
maybe we can backport the fixes...

>	Record has unlimited length, it consists of multiple message,
>and bounds of record are visible via MSG_EOR flag returned from
>'recvmsg()' call. Sender passes MSG_EOR to sending system call and
>receiver will see MSG_EOR when corresponding message will be processed.
>	To support MSG_EOR new bit was added along with existing
>'VIRTIO_VSOCK_SEQ_EOR': 'VIRTIO_VSOCK_SEQ_EOM'(end-of-message) - now it
>works in the same way as 'VIRTIO_VSOCK_SEQ_EOR'. But 'VIRTIO_VSOCK_SEQ_EOR'
>is used to mark 'MSG_EOR' bit passed from userspace.

I understand that it makes sense to remap VIRTIO_VSOCK_SEQ_EOR to 
MSG_EOR to make the user understand the boundaries, but why do we need 
EOM as well?

Why do we care about the boundaries of a message within a record?
I mean, if the sender makes 3 calls:
     send(A1,0)
     send(A2,0)
     send(A3, MSG_EOR);

IIUC it should be fine if the receiver for example receives all in one 
single recv() calll with MSG_EOR set, so why do we need EOM?

Thanks,
Stefano


  parent reply	other threads:[~2021-08-04 12:57 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 16:31 Arseny Krasnov
2021-07-26 16:33 ` [RFC PATCH v1 1/7] virtio/vsock: add 'VIRTIO_VSOCK_SEQ_EOM' bit Arseny Krasnov
2021-08-06  7:18   ` Stefano Garzarella
2021-07-26 16:33 ` [RFC PATCH v1 2/7] vsock: rename implementation from 'record' to 'message' Arseny Krasnov
2021-08-06  7:20   ` Stefano Garzarella
2021-07-26 16:33 ` [RFC PATCH v1 3/7] vhost/vsock: support MSG_EOR bit processing Arseny Krasnov
2021-08-06  7:28   ` Stefano Garzarella
2021-08-06  8:40     ` Arseny Krasnov
2021-08-06  8:47       ` Stefano Garzarella
2021-07-26 16:33 ` [RFC PATCH v1 4/7] virito/vsock: " Arseny Krasnov
2021-07-26 16:34 ` [RFC PATCH v1 5/7] af_vsock: rename variables in receive loop Arseny Krasnov
2021-07-26 16:34 ` [RFC PATCH v1 6/7] vsock_test: update message bounds test for MSG_EOR Arseny Krasnov
2021-07-26 16:34 ` [RFC PATCH v1 7/7] vsock_test: 'SO_RCVTIMEO' test for SEQPACKET Arseny Krasnov
2021-07-27  7:59 ` [RFC PATCH v1 0/7] virtio/vsock: introduce MSG_EOR flag " Stefano Garzarella
2021-07-27  9:34   ` [MASSMAIL KLMS] " Arseny Krasnov
2021-07-27  9:58     ` Stefano Garzarella
2021-07-27 12:35       ` [MASSMAIL KLMS] " Arseny Krasnov
2021-08-04 12:57 ` Stefano Garzarella [this message]
2021-08-05  8:33   ` Arseny Krasnov
2021-08-05  9:06     ` Stefano Garzarella
2021-08-05  9:21       ` [!!Mass Mail KSE][MASSMAIL KLMS] " Arseny Krasnov
2021-08-06  7:16         ` Stefano Garzarella

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210804125737.kbgc6mg2v5lw25wu@steredhat \
    --to=sgarzare@redhat.com \
    --cc=andraprs@amazon.com \
    --cc=arseny.krasnov@kaspersky.com \
    --cc=colin.king@canonical.com \
    --cc=davem@davemloft.net \
    --cc=jasowang@redhat.com \
    --cc=kuba@kernel.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mst@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=nslusarek@gmx.net \
    --cc=oxffffaa@gmail.com \
    --cc=stefanha@redhat.com \
    --cc=virtualization@lists.linux-foundation.org \
    --subject='Re: [RFC PATCH v1 0/7] virtio/vsock: introduce MSG_EOR flag for SEQPACKET' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).