On 11.02.2021 17:57, Stefano Garzarella wrote: > Hi Arseny, > > On Mon, Feb 08, 2021 at 09:32:59AM +0300, Arseny Krasnov wrote: >> On 07.02.2021 19:20, Michael S. Tsirkin wrote: >>> On Sun, Feb 07, 2021 at 06:12:56PM +0300, Arseny Krasnov wrote: >>>> This patchset impelements support of SOCK_SEQPACKET for virtio >>>> transport. >>>> As SOCK_SEQPACKET guarantees to save record boundaries, so to >>>> do it, two new packet operations were added: first for start of record >>>> and second to mark end of record(SEQ_BEGIN and SEQ_END later). Also, >>>> both operations carries metadata - to maintain boundaries and payload >>>> integrity. Metadata is introduced by adding special header with two >>>> fields - message count and message length: >>>> >>>> struct virtio_vsock_seq_hdr { >>>> __le32 msg_cnt; >>>> __le32 msg_len; >>>> } __attribute__((packed)); >>>> >>>> This header is transmitted as payload of SEQ_BEGIN and SEQ_END >>>> packets(buffer of second virtio descriptor in chain) in the same way as >>>> data transmitted in RW packets. Payload was chosen as buffer for this >>>> header to avoid touching first virtio buffer which carries header of >>>> packet, because someone could check that size of this buffer is equal >>>> to size of packet header. To send record, packet with start marker is >>>> sent first(it's header contains length of record and counter), then >>>> counter is incremented and all data is sent as usual 'RW' packets and >>>> finally SEQ_END is sent(it also carries counter of message, which is >>>> counter of SEQ_BEGIN + 1), also after sedning SEQ_END counter is >>>> incremented again. On receiver's side, length of record is known from >>>> packet with start record marker. To check that no packets were dropped >>>> by transport, counters of two sequential SEQ_BEGIN and SEQ_END are >>>> checked(counter of SEQ_END must be bigger that counter of SEQ_BEGIN by >>>> 1) and length of data between two markers is compared to length in >>>> SEQ_BEGIN header. >>>> Now as packets of one socket are not reordered neither on >>>> vsock nor on vhost transport layers, such markers allows to restore >>>> original record on receiver's side. If user's buffer is smaller that >>>> record length, when all out of size data is dropped. >>>> Maximum length of datagram is not limited as in stream socket, >>>> because same credit logic is used. Difference with stream socket is >>>> that user is not woken up until whole record is received or error >>>> occurred. Implementation also supports 'MSG_EOR' and 'MSG_TRUNC' flags. >>>> Tests also implemented. >>>> >>>> Arseny Krasnov (17): >>>> af_vsock: update functions for connectible socket >>>> af_vsock: separate wait data loop >>>> af_vsock: separate receive data loop >>>> af_vsock: implement SEQPACKET receive loop >>>> af_vsock: separate wait space loop >>>> af_vsock: implement send logic for SEQPACKET >>>> af_vsock: rest of SEQPACKET support >>>> af_vsock: update comments for stream sockets >>>> virtio/vsock: dequeue callback for SOCK_SEQPACKET >>>> virtio/vsock: fetch length for SEQPACKET record >>>> virtio/vsock: add SEQPACKET receive logic >>>> virtio/vsock: rest of SOCK_SEQPACKET support >>>> virtio/vsock: setup SEQPACKET ops for transport >>>> vhost/vsock: setup SEQPACKET ops for transport >>>> vsock_test: add SOCK_SEQPACKET tests >>>> loopback/vsock: setup SEQPACKET ops for transport >>>> virtio/vsock: simplify credit update function API >>>> >>>> drivers/vhost/vsock.c | 8 +- >>>> include/linux/virtio_vsock.h | 15 + >>>> include/net/af_vsock.h | 9 + >>>> include/uapi/linux/virtio_vsock.h | 16 + >>>> net/vmw_vsock/af_vsock.c | 588 +++++++++++++++------- >>>> net/vmw_vsock/virtio_transport.c | 5 + >>>> net/vmw_vsock/virtio_transport_common.c | 316 ++++++++++-- >>>> net/vmw_vsock/vsock_loopback.c | 5 + >>>> tools/testing/vsock/util.c | 32 +- >>>> tools/testing/vsock/util.h | 3 + >>>> tools/testing/vsock/vsock_test.c | 126 +++++ >>>> 11 files changed, 895 insertions(+), 228 deletions(-) >>>> >>>> TODO: >>>> - What to do, when server doesn't support SOCK_SEQPACKET. In current >>>> implementation RST is replied in the same way when listening port >>>> is not found. I think that current RST is enough,because case when >>>> server doesn't support SEQ_PACKET is same when listener missed(e.g. >>>> no listener in both cases). > I think is fine. > >>> - virtio spec patch >> Ok > Yes, please prepare a patch to discuss the VIRTIO spec changes. > > For example for 'virtio_vsock_seq_hdr', I left a comment about 'msg_cnt' > naming that should be better to discuss with virtio guys. Ok, i'll prepare it in v5. So I have to send it both LKML(as one of patches) and virtio mailing lists? (e.g. virtio-comment@xxxxxxxxxxxxxxxxxxxx) > > Anyway, I reviewed this series and I left some comments. > I think we are in a good shape :-) Great, thanks for review. I'll consider all review comments in next version. > > Thanks, > Stefano > >