Stefano Garzarella
2021-Mar-15 11:40 UTC
[RFC PATCH v6 00/22] virtio/vsock: introduce SOCK_SEQPACKET support
Hi Arseny, On Sun, Mar 07, 2021 at 08:57:19PM +0300, Arseny Krasnov wrote:> This patchset implements 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 id and message length: > > struct virtio_vsock_seq_hdr { > __le32 msg_id; > __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 carries length of record and id),then all data >is sent as usual 'RW' packets and finally SEQ_END is sent(it carries >id of message, which is equal to id of SEQ_BEGIN), also after sending >SEQ_END id is incremented. On receiver's side,size of record is known >from packet with start record marker. To check that no packets were >dropped by transport, 'msg_id's of two sequential SEQ_BEGIN and SEQ_END >are checked to be equal and length of data between two markers is >compared to then 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. > > Thanks to stsp2 at yandex.ru for encouragements and initial design >recommendations. > > Arseny Krasnov (22): > 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: set packet's type in virtio_transport_send_pkt_info() > virtio/vsock: simplify credit update function API > 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: SEQPACKET feature bit > vhost/vsock: SEQPACKET feature bit support > virtio/vsock: SEQPACKET feature bit support > virtio/vsock: setup SEQPACKET ops for transport > vhost/vsock: setup SEQPACKET ops for transport > vsock/loopback: setup SEQPACKET ops for transport > vsock_test: add SOCK_SEQPACKET tests > virtio/vsock: update trace event for SEQPACKET > > drivers/vhost/vsock.c | 22 +- > include/linux/virtio_vsock.h | 22 + > include/net/af_vsock.h | 10 + > .../events/vsock_virtio_transport_common.h | 48 +- > include/uapi/linux/virtio_vsock.h | 19 + > net/vmw_vsock/af_vsock.c | 589 +++++++++++------ > net/vmw_vsock/virtio_transport.c | 18 + > net/vmw_vsock/virtio_transport_common.c | 364 ++++++++-- > net/vmw_vsock/vsock_loopback.c | 13 + > tools/testing/vsock/util.c | 32 +- > tools/testing/vsock/util.h | 3 + > tools/testing/vsock/vsock_test.c | 126 ++++ > 12 files changed, 1013 insertions(+), 253 deletions(-) > > v5 -> v6: > General changelog: > - virtio transport specific callbacks which send SEQ_BEGIN or > SEQ_END now hidden inside virtio transport. Only enqueue, > dequeue and record length callbacks are provided by transport. > > - virtio feature bit for SEQPACKET socket support introduced: > VIRTIO_VSOCK_F_SEQPACKET. > > - 'msg_cnt' field in 'struct virtio_vsock_seq_hdr' renamed to > 'msg_id' and used as id. > > Per patch changelog: > - 'af_vsock: separate wait data loop': > 1) Commit message updated. > 2) 'prepare_to_wait()' moved inside while loop(thanks to > Jorgen Hansen). > Marked 'Reviewed-by' with 1), but as 2) I removed R-b. > > - 'af_vsock: separate receive data loop': commit message > updated. > Marked 'Reviewed-by' with that fix. > > - 'af_vsock: implement SEQPACKET receive loop': style fixes. > > - 'af_vsock: rest of SEQPACKET support': > 1) 'module_put()' added when transport callback check failed. > 2) Now only 'seqpacket_allow()' callback called to check > support of SEQPACKET by transport. > > - 'af_vsock: update comments for stream sockets': commit message > updated. > Marked 'Reviewed-by' with that fix. > > - 'virtio/vsock: set packet's type in send': > 1) Commit message updated. > 2) Parameter 'type' from 'virtio_transport_send_credit_update()' > also removed in this patch instead of in next. > > - 'virtio/vsock: dequeue callback for SOCK_SEQPACKET': SEQPACKET > related state wrapped to special struct. > > - 'virtio/vsock: update trace event for SEQPACKET': format strings > now not broken by new lines.I left a bunch of comments in the patches, I hope they are easy to fix :-) Thanks for the changelogs. About 'per patch changelog', it is very useful! Just a suggestion, I think is better to include them in each patch after the '---' to simplify the review. You can use git-notes(1) or you can simply edit the format-patch and add the changelog after the 3 dashes, so that they are ignored when the patch is applied. Thanks, Stefano