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From:   Arseny Krasnov <arseny.krasnov@kaspersky.com>
To:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
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        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Arseny Krasnov <arseny.krasnov@kaspersky.com>,
        Jorgen Hansen <jhansen@vmware.com>,
        Colin Ian King <colin.king@canonical.com>,
        Andra Paraschiv <andraprs@amazon.com>,
        Jeff Vander Stoep <jeffv@google.com>
CC:     <kvm@vger.kernel.org>, <virtualization@lists.linux-foundation.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <stsp2@yandex.ru>, <oxffffaa@gmail.com>
Subject: [RFC PATCH v4 05/17] af_vsock: separate wait space loop
Date:   Sun, 7 Feb 2021 18:15:41 +0300
Message-ID: <20210207151545.804889-1-arseny.krasnov@kaspersky.com>
In-Reply-To: <20210207151259.803917-1-arseny.krasnov@kaspersky.com>
References: <20210207151259.803917-1-arseny.krasnov@kaspersky.com>
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This moves loop that waits for space on send to separate function,
because it will be used for SEQ_BEGIN/SEQ_END sending before and
after data transmission. Waiting for SEQ_BEGIN/SEQ_END is needed
because such packets carries SEQPACKET header that couldn't be
fragmented by credit mechanism, so to avoid it, sender waits until
enough space will be ready.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 include/net/af_vsock.h   |  2 +
 net/vmw_vsock/af_vsock.c | 93 ++++++++++++++++++++++++++--------------
 2 files changed, 62 insertions(+), 33 deletions(-)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index bb6a0e52be86..19f6f22821ec 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -205,6 +205,8 @@ void vsock_remove_sock(struct vsock_sock *vsk);
 void vsock_for_each_connected_socket(void (*fn)(struct sock *sk));
 int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk);
 bool vsock_find_cid(unsigned int cid);
+int vsock_wait_space(struct sock *sk, size_t space, int flags,
+		     struct vsock_transport_send_notify_data *send_data);
 
 /**** TAP ****/
 
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 3d8af987216a..ea99261e88ac 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1693,6 +1693,64 @@ static int vsock_connectible_getsockopt(struct socket *sock,
 	return 0;
 }
 
+int vsock_wait_space(struct sock *sk, size_t space, int flags,
+		     struct vsock_transport_send_notify_data *send_data)
+{
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	long timeout;
+	int err;
+
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+	vsk = vsock_sk(sk);
+	transport = vsk->transport;
+	timeout = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+	err = 0;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+
+	while (vsock_stream_has_space(vsk) < space &&
+	       sk->sk_err == 0 &&
+	       !(sk->sk_shutdown & SEND_SHUTDOWN) &&
+	       !(vsk->peer_shutdown & RCV_SHUTDOWN)) {
+		/* Don't wait for non-blocking sockets. */
+		if (timeout == 0) {
+			err = -EAGAIN;
+			goto out_err;
+		}
+
+		if (send_data) {
+			err = transport->notify_send_pre_block(vsk, send_data);
+			if (err < 0)
+				goto out_err;
+		}
+
+		release_sock(sk);
+		timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout);
+		lock_sock(sk);
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeout);
+			goto out_err;
+		} else if (timeout == 0) {
+			err = -EAGAIN;
+			goto out_err;
+		}
+	}
+
+	if (sk->sk_err) {
+		err = -sk->sk_err;
+	} else if ((sk->sk_shutdown & SEND_SHUTDOWN) ||
+		   (vsk->peer_shutdown & RCV_SHUTDOWN)) {
+		err = -EPIPE;
+	}
+
+out_err:
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return err;
+}
+EXPORT_SYMBOL_GPL(vsock_wait_space);
+
 static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
 				     size_t len)
 {
@@ -1751,39 +1809,8 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
 	while (total_written < len) {
 		ssize_t written;
 
-		add_wait_queue(sk_sleep(sk), &wait);
-		while (vsock_stream_has_space(vsk) == 0 &&
-		       sk->sk_err == 0 &&
-		       !(sk->sk_shutdown & SEND_SHUTDOWN) &&
-		       !(vsk->peer_shutdown & RCV_SHUTDOWN)) {
-
-			/* Don't wait for non-blocking sockets. */
-			if (timeout == 0) {
-				err = -EAGAIN;
-				remove_wait_queue(sk_sleep(sk), &wait);
-				goto out_err;
-			}
-
-			err = transport->notify_send_pre_block(vsk, &send_data);
-			if (err < 0) {
-				remove_wait_queue(sk_sleep(sk), &wait);
-				goto out_err;
-			}
-
-			release_sock(sk);
-			timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout);
-			lock_sock(sk);
-			if (signal_pending(current)) {
-				err = sock_intr_errno(timeout);
-				remove_wait_queue(sk_sleep(sk), &wait);
-				goto out_err;
-			} else if (timeout == 0) {
-				err = -EAGAIN;
-				remove_wait_queue(sk_sleep(sk), &wait);
-				goto out_err;
-			}
-		}
-		remove_wait_queue(sk_sleep(sk), &wait);
+		if (vsock_wait_space(sk, 1, msg->msg_flags, &send_data))
+			goto out_err;
 
 		/* These checks occur both as part of and after the loop
 		 * conditional since we need to check before and after
-- 
2.25.1