| Message ID | 20210810113901.1214116-1-arseny.krasnov@kaspersky.com |
|---|---|
| Headers | show |
| Series | virtio/vsock: introduce MSG_EOR flag for SEQPACKET | expand |
On Tue, Aug 10, 2021 at 02:40:15PM +0300, Arseny Krasnov wrote: >It works in the same way as 'end-of-message' bit: if packet has >'EOM' bit, also check for 'EOR' bit. Please describe all changes, e.g. the new variable to accumulate flags to restore. > >Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com> >--- > drivers/vhost/vsock.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > >diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c >index feaf650affbe..06fc132b13c8 100644 >--- a/drivers/vhost/vsock.c >+++ b/drivers/vhost/vsock.c >@@ -114,7 +114,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock, > size_t nbytes; > size_t iov_len, payload_len; > int head; >- bool restore_flag = false; >+ uint32_t flags_to_restore = 0; > > spin_lock_bh(&vsock->send_pkt_list_lock); > if (list_empty(&vsock->send_pkt_list)) { >@@ -187,7 +187,12 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock, > */ > if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) { > pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM); >- restore_flag = true; >+ flags_to_restore |= le32_to_cpu(VIRTIO_VSOCK_SEQ_EOM); >+ >+ if (le32_to_cpu(pkt->hdr.flags & VIRTIO_VSOCK_SEQ_EOR)) { >+ pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR); >+ flags_to_restore |= le32_to_cpu(VIRTIO_VSOCK_SEQ_EOR); ^ I'm not sure this is needed, VIRTIO_VSOCK_SEQ_EOR is represented in the cpu endianess. I think here you can simpy do `flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR` then use `pkt->hdr.flags |= cpu_to_le32(flags_to_restore);` as you already do. >+ } > } > } > >@@ -224,8 +229,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock, > * to send it with the next available buffer. > */ > if (pkt->off < pkt->len) { >- if (restore_flag) >- pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM); >+ pkt->hdr.flags |= cpu_to_le32(flags_to_restore); > > /* We are queueing the same virtio_vsock_pkt to handle > * the remaining bytes, and we want to deliver it >-- >2.25.1 >
On Tue, Aug 10, 2021 at 02:41:00PM +0300, Arseny Krasnov wrote: >Record is supported via MSG_EOR flag, while current logic operates >with message, so rename variables from 'record' to 'message'. > >Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com> >--- > net/vmw_vsock/af_vsock.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > >diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c >index 3e02cc3b24f8..e2c0cfb334d2 100644 >--- a/net/vmw_vsock/af_vsock.c >+++ b/net/vmw_vsock/af_vsock.c >@@ -2014,7 +2014,7 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg, > { > const struct vsock_transport *transport; > struct vsock_sock *vsk; >- ssize_t record_len; >+ ssize_t msg_len; > long timeout; > int err = 0; > DEFINE_WAIT(wait); >@@ -2028,9 +2028,9 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg, > if (err <= 0) > goto out; > >- record_len = transport->seqpacket_dequeue(vsk, msg, flags); >+ msg_len = transport->seqpacket_dequeue(vsk, msg, flags); > >- if (record_len < 0) { >+ if (msg_len < 0) { > err = -ENOMEM; > goto out; > } >@@ -2044,14 +2044,14 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg, > * packet. > */ > if (flags & MSG_TRUNC) >- err = record_len; >+ err = msg_len; > else > err = len - msg_data_left(msg); > > /* Always set MSG_TRUNC if real length of packet is > * bigger than user's buffer. > */ >- if (record_len > len) >+ if (msg_len > len) > msg->msg_flags |= MSG_TRUNC; > } > >-- >2.25.1 > Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
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 messages, 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. Arseny Krasnov(5): virtio/vsock: add 'VIRTIO_VSOCK_SEQ_EOM' bit 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 drivers/vhost/vsock.c | 22 +++++++++++++--------- include/uapi/linux/virtio_vsock.h | 3 ++- net/vmw_vsock/af_vsock.c | 10 +++++----- net/vmw_vsock/virtio_transport_common.c | 23 +++++++++++++++-------- tools/testing/vsock/vsock_test.c | 8 +++++++- 5 files changed, 42 insertions(+), 24 deletions(-) v1 -> v2: - 'VIRTIO_VSOCK_SEQ_EOR' is renamed to 'VIRTIO_VSOCK_SEQ_EOM', to support backward compatibility. - use bitmask of flags to restore in vhost.c, instead of separated bool variable for each flag. - test for EAGAIN removed, as logically it is not part of this patchset(will be sent separately). - cover letter updated(added part with POSIX description). Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>