Re: [MASSMAIL KLMS] Re: [MASSMAIL KLMS] Re: [RFC PATCH v1 0/7] virtio/vsock: introduce MSG_EOR flag for SEQPACKET

[Arseny Krasnov]

On 27.07.2021 12:58, Stefano Garzarella wrote:
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> On Tue, Jul 27, 2021 at 12:34:36PM +0300, Arseny Krasnov wrote:
>> On 27.07.2021 10:59, Stefano Garzarella wrote:
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>>> 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.
>>>>       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.
>>> At this point it's probably better to rename the old flag, so we stay
>>> compatible.
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>>> What happens if one of the two peers does not support MSG_EOR handling,
>>> while the other does?
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>>> I'll do a closer review in the next few days.
>> Thank You, also i think MSG_EOR support must be described in spec
> Yep, sure!
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> What do you think about the concerns above?
I think you are right, i'll rename EOR -> EOM, and EOR will be added by patch
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> Stefano
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