Re: [PATCH RFC net-next v4 1/8] vsock/dgram: generalize recvmsg and drop transport->dgram_dequeue
From: Stefano Garzarella
Date: Fri Jun 23 2023 - 04:15:31 EST
On Thu, Jun 22, 2023 at 11:37:42PM +0000, Bobby Eshleman wrote:
On Thu, Jun 22, 2023 at 04:51:41PM +0200, Stefano Garzarella wrote:
On Sun, Jun 11, 2023 at 11:43:15PM +0300, Arseniy Krasnov wrote:
> Hello Bobby! Thanks for this patchset! Small comment below:
>
> On 10.06.2023 03:58, Bobby Eshleman wrote:
> > This commit drops the transport->dgram_dequeue callback and makes
> > vsock_dgram_recvmsg() generic. It also adds additional transport
> > callbacks for use by the generic vsock_dgram_recvmsg(), such as for
> > parsing skbs for CID/port which vary in format per transport.
> >
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
> > ---
> > drivers/vhost/vsock.c | 4 +-
> > include/linux/virtio_vsock.h | 3 ++
> > include/net/af_vsock.h | 13 ++++++-
> > net/vmw_vsock/af_vsock.c | 51 ++++++++++++++++++++++++-
> > net/vmw_vsock/hyperv_transport.c | 17 +++++++--
> > net/vmw_vsock/virtio_transport.c | 4 +-
> > net/vmw_vsock/virtio_transport_common.c | 18 +++++++++
> > net/vmw_vsock/vmci_transport.c | 68 +++++++++++++--------------------
> > net/vmw_vsock/vsock_loopback.c | 4 +-
> > 9 files changed, 132 insertions(+), 50 deletions(-)
> >
> > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > index 6578db78f0ae..c8201c070b4b 100644
> > --- a/drivers/vhost/vsock.c
> > +++ b/drivers/vhost/vsock.c
> > @@ -410,9 +410,11 @@ static struct virtio_transport vhost_transport = {
> > .cancel_pkt = vhost_transport_cancel_pkt,
> >
> > .dgram_enqueue = virtio_transport_dgram_enqueue,
> > - .dgram_dequeue = virtio_transport_dgram_dequeue,
> > .dgram_bind = virtio_transport_dgram_bind,
> > .dgram_allow = virtio_transport_dgram_allow,
> > + .dgram_get_cid = virtio_transport_dgram_get_cid,
> > + .dgram_get_port = virtio_transport_dgram_get_port,
> > + .dgram_get_length = virtio_transport_dgram_get_length,
> >
> > .stream_enqueue = virtio_transport_stream_enqueue,
> > .stream_dequeue = virtio_transport_stream_dequeue,
> > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> > index c58453699ee9..23521a318cf0 100644
> > --- a/include/linux/virtio_vsock.h
> > +++ b/include/linux/virtio_vsock.h
> > @@ -219,6 +219,9 @@ bool virtio_transport_stream_allow(u32 cid, u32 port);
> > int virtio_transport_dgram_bind(struct vsock_sock *vsk,
> > struct sockaddr_vm *addr);
> > bool virtio_transport_dgram_allow(u32 cid, u32 port);
> > +int virtio_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid);
> > +int virtio_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port);
> > +int virtio_transport_dgram_get_length(struct sk_buff *skb, size_t *len);
> >
> > int virtio_transport_connect(struct vsock_sock *vsk);
> >
> > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> > index 0e7504a42925..7bedb9ee7e3e 100644
> > --- a/include/net/af_vsock.h
> > +++ b/include/net/af_vsock.h
> > @@ -120,11 +120,20 @@ struct vsock_transport {
> >
> > /* DGRAM. */
> > int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *);
> > - int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
> > - size_t len, int flags);
> > int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
> > struct msghdr *, size_t len);
> > bool (*dgram_allow)(u32 cid, u32 port);
> > + int (*dgram_get_cid)(struct sk_buff *skb, unsigned int *cid);
> > + int (*dgram_get_port)(struct sk_buff *skb, unsigned int *port);
> > + int (*dgram_get_length)(struct sk_buff *skb, size_t *length);
> > +
> > + /* The number of bytes into the buffer at which the payload starts, as
> > + * first seen by the receiving socket layer. For example, if the
> > + * transport presets the skb pointers using skb_pull(sizeof(header))
> > + * than this would be zero, otherwise it would be the size of the
> > + * header.
> > + */
> > + const size_t dgram_payload_offset;
> >
> > /* STREAM. */
> > /* TODO: stream_bind() */
> > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > index efb8a0937a13..ffb4dd8b6ea7 100644
> > --- a/net/vmw_vsock/af_vsock.c
> > +++ b/net/vmw_vsock/af_vsock.c
> > @@ -1271,11 +1271,15 @@ static int vsock_dgram_connect(struct socket *sock,
> > int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> > size_t len, int flags)
> > {
> > + const struct vsock_transport *transport;
> > #ifdef CONFIG_BPF_SYSCALL
> > const struct proto *prot;
> > #endif
> > struct vsock_sock *vsk;
> > + struct sk_buff *skb;
> > + size_t payload_len;
> > struct sock *sk;
> > + int err;
> >
> > sk = sock->sk;
> > vsk = vsock_sk(sk);
> > @@ -1286,7 +1290,52 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> > return prot->recvmsg(sk, msg, len, flags, NULL);
> > #endif
> >
> > - return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
> > + if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
> > + return -EOPNOTSUPP;
> > +
> > + transport = vsk->transport;
> > +
> > + /* Retrieve the head sk_buff from the socket's receive queue. */
> > + err = 0;
> > + skb = skb_recv_datagram(sk_vsock(vsk), flags, &err);
> > + if (!skb)
> > + return err;
> > +
> > + err = transport->dgram_get_length(skb, &payload_len);
What about ssize_t return value here?
Or maybe a single callback that return both length and offset?
.dgram_get_payload_info(skb, &payload_len, &payload_off)
What are your thoughts on Arseniy's idea of using skb->len and adding a
skb_pull() just before vmci adds the skb to the sk receive queue?
Yep, I agree on that!
Thanks,
Stefano