netdev - [RFC PATCH v1 08/16] af_vsock: change SEQPACKET receive loop

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Message-ID: <20210628100331.571056-1-arseny.krasnov@kaspersky.com>
Date:   Mon, 28 Jun 2021 13:03:28 +0300
From:   Arseny Krasnov <arseny.krasnov@...persky.com>
To:     Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Arseny Krasnov <arseny.krasnov@...persky.com>,
        Jorgen Hansen <jhansen@...are.com>,
        Andra Paraschiv <andraprs@...zon.com>,
        Colin Ian King <colin.king@...onical.com>,
        Norbert Slusarek <nslusarek@....net>
CC:     <kvm@...r.kernel.org>, <virtualization@...ts.linux-foundation.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <oxffffaa@...il.com>
Subject: [RFC PATCH v1 08/16] af_vsock: change SEQPACKET receive loop

Receive "loop" now really loop: it reads fragments one by
one, sleeping if queue is empty.

NOTE: 'msg_ready' pointer is not passed to 'seqpacket_dequeue()'
here - it change callback interface, so it is moved to next patch.

Signed-off-by: Arseny Krasnov <arseny.krasnov@...persky.com>
---
 net/vmw_vsock/af_vsock.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 59ce35da2e5b..9552f05119f2 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2003,6 +2003,7 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
 				     size_t len, int flags)
 {
 	const struct vsock_transport *transport;
+	bool msg_ready;
 	struct vsock_sock *vsk;
 	ssize_t record_len;
 	long timeout;
@@ -2013,23 +2014,36 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
 	transport = vsk->transport;
 
 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+	msg_ready = false;
+	record_len = 0;
 
-	err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
-	if (err <= 0)
-		goto out;
+	while (!msg_ready) {
+		ssize_t fragment_len;
+		int intr_err;
 
-	record_len = transport->seqpacket_dequeue(vsk, msg, flags);
+		intr_err = vsock_connectible_wait_data(sk, &wait, timeout, NULL, 0);
+		if (intr_err <= 0) {
+			err = intr_err;
+			break;
+		}
 
-	if (record_len < 0) {
-		err = -ENOMEM;
-		goto out;
+		fragment_len = transport->seqpacket_dequeue(vsk, msg, flags);
+
+		if (fragment_len < 0) {
+			err = -ENOMEM;
+			break;
+		}
+
+		record_len += fragment_len;
 	}
 
 	if (sk->sk_err) {
 		err = -sk->sk_err;
 	} else if (sk->sk_shutdown & RCV_SHUTDOWN) {
 		err = 0;
-	} else {
+	}
+
+	if (msg_ready && !err) {
 		/* User sets MSG_TRUNC, so return real length of
 		 * packet.
 		 */
@@ -2045,7 +2059,6 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
 			msg->msg_flags |= MSG_TRUNC;
 	}
 
-out:
 	return err;
 }
 
-- 
2.25.1