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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2aae33faf4sm173417566b.3.2026.09.23.11.40.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 11:40:11 -0700 (PDT) From: David Carlier To: netdev@vger.kernel.org Cc: sgarzare@redhat.com, bobbyeshleman@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, David Carlier Subject: [PATCH net-next v2 1/2] vsock: report pending receive data to io_uring Date: Wed, 23 Sep 2026 19:40:07 +0100 Message-ID: <20260923184008.153541-2-devnexen@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260923184008.153541-1-devnexen@gmail.com> References: <20260923184008.153541-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit AF_VSOCK stream receives never fill msghdr.msg_inq, so io_uring cannot set IORING_CQE_F_SOCK_NONEMPTY and retries a multishot receive even after the queue has been drained. Fill the hint at the common receive exit using the transport callback that SIOCINQ already uses, and report 1 once the connection is finished so the caller performs the receive which observes EOF, as TCP does after a FIN. A vsock loopback ping-pong with io_uring multishot receive drops entries into __vsock_connectible_recvmsg from 1.97 to 1.00 per delivered message, and receiver CPU time by about 3% (25 runs of 50000 messages, p=0.006). Signed-off-by: David Carlier --- net/vmw_vsock/af_vsock.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index f840498b58af..20d6f9ca6a96 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -2543,6 +2543,35 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg, return err; } +/* Bytes a following receive can consume, 1 if it would only see EOF, or -1 + * if the transport cannot tell. + * + * Called under the socket lock after a nonnegative stream receive, so a NULL + * transport implies SOCK_DONE. + */ +static int vsock_stream_inq_hint(struct sock *sk) +{ + struct vsock_sock *vsk = vsock_sk(sk); + s64 data; + + if ((sk->sk_shutdown & RCV_SHUTDOWN) || !vsk->transport || + (sock_flag(sk, SOCK_DONE) && sk->sk_state != TCP_ESTABLISHED)) + return 1; + + data = vsock_stream_has_data(vsk); + if (data < 0) + return -1; + if (data > 0) + return min_t(s64, data, INT_MAX); + + /* Empty but finished: keep the caller reading so it sees EOF. */ + if (sock_flag(sk, SOCK_DONE) || + (READ_ONCE(vsk->peer_shutdown) & SEND_SHUTDOWN)) + return 1; + + return 0; +} + int __vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, int flags) @@ -2606,6 +2635,12 @@ __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. + */ + if (msg->msg_get_inq && err >= 0 && sk->sk_type == SOCK_STREAM) + msg->msg_inq = vsock_stream_inq_hint(sk); + release_sock(sk); return err; } -- 2.55.0