On Tue, Oct 13, 2026 at 12:55:23AM +0100, David Carlier wrote:
SO_INQ makes recvmsg() return the bytes left in the receive queue in an
SCM_INQ cmsg, saving a SIOCINQ call per receive. AF_UNIX stream sockets
support it, AF_VSOCK fails with ENOPROTOOPT.
Add it for SOCK_STREAM, reusing the hint already computed for io_uring.
As with TCP_INQ, 1 is reported once the stream is finished so the caller
reads again and sees EOF. No cmsg is sent when the transport cannot
report the queue length.
SOCK_SEQPACKET is refused, as on AF_UNIX: its transport callback counts
messages, not bytes.
Signed-off-by: David Carlier <[email protected]>
---
include/net/af_vsock.h | 1 +
net/vmw_vsock/af_vsock.c | 41 +++++++++++++++++++++++++++++++---------
2 files changed, 33 insertions(+), 9 deletions(-)
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 5549298c1ec6..e8481f12312e 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -68,6 +68,7 @@ struct vsock_sock {
u64 buffer_size;
u64 buffer_min_size;
u64 buffer_max_size;
+ bool recvmsg_inq;
/* Private to transport. */
void *trans;
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 1c2d1cea67f4..874dc1545a35 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2050,29 +2050,38 @@ static int vsock_connectible_setsockopt(struct socket
*sock,
transport = vsk->transport;
if (level == SOL_SOCKET) {
- int zerocopy;
+ int v;
Please use a variable with a better name.
- if (optname != SO_ZEROCOPY) {
+ if (optname != SO_ZEROCOPY && optname != SO_INQ) {
Can we add something like unix_custom_sockopt()?
release_sock(sk);
return sock_setsockopt(sock, level, optname, optval,
optlen);
}
/* Use 'int' type here, because variable to
- * set this option usually has this type.
+ * set these options usually has this type.
*/
- COPY_IN(zerocopy);
+ COPY_IN(v);
- if (zerocopy < 0 || zerocopy > 1) {
+ if (v < 0 || v > 1) {
err = -EINVAL;
goto exit;
}
+ if (optname == SO_INQ) {
+ if (sk->sk_type != SOCK_STREAM) {
+ err = -ENOPROTOOPT;
+ goto exit;
+ }
+ vsk->recvmsg_inq = v;
Should child sockets inherit this from a listener socket?
+ goto exit;
+ }
Please add a switch to handle SO_INQ and SO_ZEROCOPY clearly.
+
if (transport && !vsock_msgzerocopy_allow(transport)) {
err = -EOPNOTSUPP;
goto exit;
}
- sock_valbool_flag(sk, SOCK_ZEROCOPY, zerocopy);
+ sock_valbool_flag(sk, SOCK_ZEROCOPY, v);
goto exit;
}
Maybe we can add a new function to handle SOL_SOCKET level, but I don't
have a strong opinion on that.
@@ -2581,6 +2590,7 @@ __vsock_connectible_recvmsg(struct socket *sock, struct
msghdr *msg, size_t len,
struct sock *sk;
struct vsock_sock *vsk;
const struct vsock_transport *transport;
+ bool do_cmsg = false;
int err;
sk = sock->sk;
@@ -2637,13 +2647,26 @@ __vsock_connectible_recvmsg(struct socket *sock, struct
msghdr *msg, size_t len,
err = __vsock_seqpacket_recvmsg(sk, msg, len, flags);
out:
- /* Seqpacket has_data counts messages, while io_uring treats msg_inq as
- * a byte length when sizing retries, so only streams report a hint.
+ /* Seqpacket has_data counts messages, while SCM_INQ reports bytes and
+ * io_uring treats msg_inq as a byte length when sizing retries, so
+ * only streams report it.
*/
- if (msg->msg_get_inq && err >= 0 && sk->sk_type == SOCK_STREAM)
+ if ((vsk->recvmsg_inq | msg->msg_get_inq) && err >= 0 &&
Is the bitwise or what we want here?
Thanks,
Stefano
+ sk->sk_type == SOCK_STREAM) {
msg->msg_inq = vsock_stream_inq_hint(sk);
+ /* A negative hint means the transport could not tell. SCM_INQ
+ * has no encoding for that, so report nothing.
+ */
+ do_cmsg = vsk->recvmsg_inq && msg->msg_inq >= 0;
+ }
+
release_sock(sk);
+
+ if (do_cmsg)
+ put_cmsg(msg, SOL_SOCKET, SCM_INQ, sizeof(msg->msg_inq),
+ &msg->msg_inq);
+
return err;
}
--
2.55.0
