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

[Arseny Krasnov <arseny.krasnov@kaspersky.com>]

	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.
	This patchset includes simple test for MSG_EOR.
 	Also i've added new vsock test for '-EAGAIN' receive result.

 Arseny Krasnov(7):
  virtio/vsock: add 'VIRTIO_VSOCK_SEQ_EOM' bit
  vsock: rename implementation from 'record' to 'message'
  vhost/vsock: support MSG_EOR bit processing
  virito/vsock: support MSG_EOR bit processing
  af_vsock: rename variables in receive loop
  vsock_test: update message bounds test for MSG_EOR
  vsock_test: 'SO_RCVTIMEO' test for SEQPACKET

 drivers/vhost/vsock.c                   | 28 +++++++----
 include/uapi/linux/virtio_vsock.h       |  1 +
 net/vmw_vsock/af_vsock.c                | 10 ++--
 net/vmw_vsock/virtio_transport_common.c | 23 +++++----
 tools/testing/vsock/vsock_test.c        | 57 ++++++++++++++++++++++-
 5 files changed, 96 insertions(+), 23 deletions(-)

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>

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2.25.1