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Fri, 16 Oct 2026 01:14:39 -0700 (PDT) Date: Fri, 16 Oct 2026 10:14:37 +0200 From: Stefano Garzarella To: David Carlier Cc: netdev@vger.kernel.org, bobbyeshleman@gmail.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v2 1/2] vsock: support SO_INQ on stream sockets Message-ID: References: <20261015154334.3217358-1-devnexen@gmail.com> <20261015154334.3217358-2-devnexen@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20261015154334.3217358-2-devnexen@gmail.com> On Thu, Oct 15, 2026 at 04:43:33PM +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, and accepted sockets inherit the setting from >the listener. 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 >--- > include/net/af_vsock.h | 1 + > net/vmw_vsock/af_vsock.c | 111 +++++++++++++++++++++++++++++---------- > 2 files changed, 84 insertions(+), 28 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..186ed57fd797 100644 >--- a/net/vmw_vsock/af_vsock.c >+++ b/net/vmw_vsock/af_vsock.c >@@ -984,6 +984,7 @@ static struct sock *__vsock_create(struct net *net, > vsk->buffer_size = psk->buffer_size; > vsk->buffer_min_size = psk->buffer_min_size; > vsk->buffer_max_size = psk->buffer_max_size; >+ vsk->recvmsg_inq = psk->recvmsg_inq; > security_sk_clone(parent, sk); > } else { > vsk->trusted = ns_capable_noaudit(&init_user_ns, CAP_NET_ADMIN); >@@ -2014,6 +2015,66 @@ static void vsock_update_buffer_size(struct vsock_sock *vsk, > vsk->buffer_size = val; > } > >+static bool vsock_custom_sockopt(int optname) Looking at the other function, what about vsock_sol_socket_custom()? >+{ >+ switch (optname) { >+ case SO_ZEROCOPY: >+ case SO_INQ: >+ return true; >+ default: >+ return false; >+ } >+} >+ >+static int vsock_sol_socket_setsockopt(struct sock *sk, int optname, >+ sockptr_t optval, unsigned int optlen) >+{ >+ struct vsock_sock *vsk = vsock_sk(sk); >+ int err = 0; >+ int val; >+ >+ /* Use 'int' type here, because variable to nit: why not using at least 80 columns for this comment? >+ * set these options usually has this type. >+ */ >+ if (optlen < sizeof(val)) >+ return -EINVAL; >+ >+ if (copy_from_sockptr(&val, optval, sizeof(val))) >+ return -EFAULT; >+ >+ if (val < 0 || val > 1) >+ return -EINVAL; What about adding an helper with this code, and call it after checks for each SO_, in this way using SO_INQ on sock_dgram with 2 will return -ENOPROTOOPT. Oh wait, we can use COPY_IN and duplicate the check in each place or add an helper just for that. >+ >+ lock_sock(sk); >+ >+ switch (optname) { >+ case SO_ZEROCOPY: >+ if (vsk->transport && !vsock_msgzerocopy_allow(vsk->transport)) { >+ err = -EOPNOTSUPP; >+ break; >+ } >+ >+ sock_valbool_flag(sk, SOCK_ZEROCOPY, val); >+ break; >+ >+ case SO_INQ: >+ if (sk->sk_type != SOCK_STREAM) { >+ err = -ENOPROTOOPT; >+ break; >+ } >+ >+ vsk->recvmsg_inq = val; >+ break; >+ >+ default: >+ err = -ENOPROTOOPT; >+ break; >+ } >+ >+ release_sock(sk); >+ return err; >+} Now it's much better, but we should not mix a refactoring with a new feature, so please split this patch in 2 patches, first one introducing vsock_sol_socket_setsockopt() just for SO_ZEROCOPY, second one introducing SO_INQ handling. In this way, if we have to backport a fix to SO_ZEROCOPY handling in a stable branch, we can do it easily. The rest LGTM, Stefano >+ > static int vsock_connectible_setsockopt(struct socket *sock, > int level, > int optname, >@@ -2045,36 +2106,16 @@ static int vsock_connectible_setsockopt(struct socket *sock, > sk = sock->sk; > vsk = vsock_sk(sk); > >- lock_sock(sk); >- >- transport = vsk->transport; >- > if (level == SOL_SOCKET) { >- int zerocopy; >- >- if (optname != SO_ZEROCOPY) { >- release_sock(sk); >+ if (!vsock_custom_sockopt(optname)) > return sock_setsockopt(sock, level, optname, optval, optlen); >- } >- >- /* Use 'int' type here, because variable to >- * set this option usually has this type. >- */ >- COPY_IN(zerocopy); > >- if (zerocopy < 0 || zerocopy > 1) { >- err = -EINVAL; >- goto exit; >- } >+ return vsock_sol_socket_setsockopt(sk, optname, optval, optlen); >+ } > >- if (transport && !vsock_msgzerocopy_allow(transport)) { >- err = -EOPNOTSUPP; >- goto exit; >- } >+ lock_sock(sk); > >- sock_valbool_flag(sk, SOCK_ZEROCOPY, zerocopy); >- goto exit; >- } >+ transport = vsk->transport; > > switch (optname) { > case SO_VM_SOCKETS_BUFFER_SIZE: >@@ -2581,6 +2622,7 @@ __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 +2679,26 @@ __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 && >+ 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 >