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From:   Arseny Krasnov <arseny.krasnov@kaspersky.com>
To:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        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>,
        Andra Paraschiv <andraprs@amazon.com>,
        Colin Ian King <colin.king@canonical.com>,
        Norbert Slusarek <nslusarek@gmx.net>
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 v6 02/22] af_vsock: separate wait data loop
Date:   Sun, 7 Mar 2021 20:59:01 +0300
Message-ID: <20210307175905.3464610-1-arseny.krasnov@kaspersky.com>
In-Reply-To: <20210307175722.3464068-1-arseny.krasnov@kaspersky.com>
References: <20210307175722.3464068-1-arseny.krasnov@kaspersky.com>
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This moves wait loop for data to dedicated function, because later it
will be used by SEQPACKET data receive loop. While moving the code
around, let's update an old comment.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 net/vmw_vsock/af_vsock.c | 156 +++++++++++++++++++++------------------
 1 file changed, 84 insertions(+), 72 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 656370e11707..421c0303b26f 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1832,6 +1832,69 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
 	return err;
 }
 
+static int vsock_wait_data(struct sock *sk, struct wait_queue_entry *wait,
+			   long timeout,
+			   struct vsock_transport_recv_notify_data *recv_data,
+			   size_t target)
+{
+	const struct vsock_transport *transport;
+	struct vsock_sock *vsk;
+	s64 data;
+	int err;
+
+	vsk = vsock_sk(sk);
+	err = 0;
+	transport = vsk->transport;
+
+	while ((data = vsock_stream_has_data(vsk)) == 0) {
+		prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
+
+		if (sk->sk_err != 0 ||
+		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+		    (vsk->peer_shutdown & SEND_SHUTDOWN)) {
+			break;
+		}
+
+		/* Don't wait for non-blocking sockets. */
+		if (timeout == 0) {
+			err = -EAGAIN;
+			break;
+		}
+
+		if (recv_data) {
+			err = transport->notify_recv_pre_block(vsk, target, recv_data);
+			if (err < 0)
+				break;
+		}
+
+		release_sock(sk);
+		timeout = schedule_timeout(timeout);
+		lock_sock(sk);
+
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeout);
+			break;
+		} else if (timeout == 0) {
+			err = -EAGAIN;
+			break;
+		}
+	}
+
+	finish_wait(sk_sleep(sk), wait);
+
+	if (err)
+		return err;
+
+	/* Internal transport error when checking for available
+	 * data. XXX This should be changed to a connection
+	 * reset in a later change.
+	 */
+	if (data < 0)
+		return -ENOMEM;
+
+	return data;
+}
+
 static int
 vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 			  int flags)
@@ -1911,85 +1974,34 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
 
 	while (1) {
-		s64 ready;
+		ssize_t read;
 
-		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
-		ready = vsock_stream_has_data(vsk);
+		err = vsock_wait_data(sk, &wait, timeout, &recv_data, target);
+		if (err <= 0)
+			break;
 
-		if (ready == 0) {
-			if (sk->sk_err != 0 ||
-			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-			    (vsk->peer_shutdown & SEND_SHUTDOWN)) {
-				finish_wait(sk_sleep(sk), &wait);
-				break;
-			}
-			/* Don't wait for non-blocking sockets. */
-			if (timeout == 0) {
-				err = -EAGAIN;
-				finish_wait(sk_sleep(sk), &wait);
-				break;
-			}
-
-			err = transport->notify_recv_pre_block(
-					vsk, target, &recv_data);
-			if (err < 0) {
-				finish_wait(sk_sleep(sk), &wait);
-				break;
-			}
-			release_sock(sk);
-			timeout = schedule_timeout(timeout);
-			lock_sock(sk);
-
-			if (signal_pending(current)) {
-				err = sock_intr_errno(timeout);
-				finish_wait(sk_sleep(sk), &wait);
-				break;
-			} else if (timeout == 0) {
-				err = -EAGAIN;
-				finish_wait(sk_sleep(sk), &wait);
-				break;
-			}
-		} else {
-			ssize_t read;
-
-			finish_wait(sk_sleep(sk), &wait);
-
-			if (ready < 0) {
-				/* Invalid queue pair content. XXX This should
-				* be changed to a connection reset in a later
-				* change.
-				*/
-
-				err = -ENOMEM;
-				goto out;
-			}
-
-			err = transport->notify_recv_pre_dequeue(
-					vsk, target, &recv_data);
-			if (err < 0)
-				break;
+		err = transport->notify_recv_pre_dequeue(vsk, target,
+							 &recv_data);
+		if (err < 0)
+			break;
 
-			read = transport->stream_dequeue(
-					vsk, msg,
-					len - copied, flags);
-			if (read < 0) {
-				err = -ENOMEM;
-				break;
-			}
+		read = transport->stream_dequeue(vsk, msg, len - copied, flags);
+		if (read < 0) {
+			err = -ENOMEM;
+			break;
+		}
 
-			copied += read;
+		copied += read;
 
-			err = transport->notify_recv_post_dequeue(
-					vsk, target, read,
-					!(flags & MSG_PEEK), &recv_data);
-			if (err < 0)
-				goto out;
+		err = transport->notify_recv_post_dequeue(vsk, target, read,
+						!(flags & MSG_PEEK), &recv_data);
+		if (err < 0)
+			goto out;
 
-			if (read >= target || flags & MSG_PEEK)
-				break;
+		if (read >= target || flags & MSG_PEEK)
+			break;
 
-			target -= read;
-		}
+		target -= read;
 	}
 
 	if (sk->sk_err)
-- 
2.25.1