Re: [RFC PATCH v2 5/9] vsock: SO_RCVLOWAT transport set callback
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2022-07-27 12:24:34
Also in:
kvm, linux-hyperv, lkml, virtualization
On Mon, Jul 25, 2022 at 08:05:28AM +0000, Arseniy Krasnov wrote:
quoted hunk ↗ jump to hunk
This adds transport specific callback for SO_RCVLOWAT, because in some transports it may be difficult to know current available number of bytes ready to read. Thus, when SO_RCVLOWAT is set, transport may reject it. Signed-off-by: Arseniy Krasnov <redacted> --- include/net/af_vsock.h | 1 + net/vmw_vsock/af_vsock.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+)diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h index f742e50207fb..eae5874bae35 100644 --- a/include/net/af_vsock.h +++ b/include/net/af_vsock.h@@ -134,6 +134,7 @@ struct vsock_transport {u64 (*stream_rcvhiwat)(struct vsock_sock *); bool (*stream_is_active)(struct vsock_sock *); bool (*stream_allow)(u32 cid, u32 port); + int (*set_rcvlowat)(struct vsock_sock *, int); /* SEQ_PACKET. */ ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 63a13fa2686a..b7a286db4af1 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c@@ -2130,6 +2130,24 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,return err; } +static int vsock_set_rcvlowat(struct sock *sk, int val) +{ + const struct vsock_transport *transport; + struct vsock_sock *vsk; + int err = 0; + + vsk = vsock_sk(sk); + transport = vsk->transport;
`transport` can be NULL if the user call SO_RCVLOWAT before we assign
it, so we should check it.
I think if the transport implements `set_rcvlowat`, maybe we should set
there sk->sk_rcvlowat, so I would do something like that:
if (transport && transport->set_rcvlowat)
err = transport->set_rcvlowat(vsk, val);
else
WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
return err;
In addition I think we should check that val does not exceed
vsk->buffer_size, something similar of what tcp_set_rcvlowat() does.
Thanks,
Stefano