On Sun, Sep 05, 2021 at 04:18:52PM -0400, Michael S. Tsirkin wrote:
On Sun, Sep 05, 2021 at 07:21:10PM +0300, Arseny Krasnov wrote:
On 05.09.2021 19:19, Michael S. Tsirkin wrote:
> On Sun, Sep 05, 2021 at 07:02:44PM +0300, Arseny Krasnov wrote:
>> On 05.09.2021 18:55, Michael S. Tsirkin wrote:
>>> On Fri, Sep 03, 2021 at 03:30:13PM +0300, Arseny Krasnov wrote:
>>>> This patchset implements support of MSG_EOR bit for SEQPACKET
>>>> AF_VSOCK sockets over virtio transport.
>>>> First we need to define 'messages' and 'records' like this:
>>>> 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.
>>>> Idea of patchset comes from POSIX: it says that SEQPACKET
>>>> supports record boundaries which are visible for receiver using
>>>> MSG_EOR bit. So, it looks like MSG_EOR is enough thing for SEQPACKET
>>>> and we don't need to maintain boundaries of corresponding send -
>>>> receive system calls. But, for 'sendXXX()' and 'recXXX()' POSIX says,
>>>> that all these calls operates with messages, e.g. 'sendXXX()' sends
>>>> message, while 'recXXX()' reads messages and for SEQPACKET, 'recXXX()'
>>>> must read one entire message from socket, dropping all out of size
>>>> bytes. Thus, both message boundaries and MSG_EOR bit must be supported
>>>> to follow POSIX rules.
>>>> 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.
>>>> This patchset includes simple test for MSG_EOR.
>>> I'm prepared to merge this for this window,
>>> but I'm not sure who's supposed to ack the net/vmw_vsock/af_vsock.c
>>> bits. It's a harmless variable renaming so maybe it does not matter.
>>>
>>> The rest is virtio stuff so I guess my tree is ok.
>>>
>>> Objections, anyone?
>> https://lkml.org/lkml/2021/9/3/76 this is v4. It is same as v5 in af_vsock.c changes.
>>
>> It has Reviewed by from Stefano Garzarella.
> Is Stefano the maintainer for af_vsock then?
> I wasn't sure.
I'm maintaining virtio-vsock stuff, but I'm reviewing most of the
af_vsock patches. We don't have an entry for it in MAINTAINERS, maybe we
should.
Ack, let's wait for maintainer's comment
The specific patch is a trivial variable renaming so
I parked this in my tree for now, will merge unless I
hear any objections in the next couple of days.
I agree, I think your tree is fine, since this series is mostly about
virtio-vsock.
Thanks,
Stefano
