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From: Stefano Garzarella <sgarzare@redhat.com>
To: Arseny Krasnov <arseny.krasnov@kaspersky.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Jorgen Hansen <jhansen@vmware.com>,
	Andra Paraschiv <andraprs@amazon.com>,
	Colin Ian King <colin.king@canonical.com>,
	Norbert Slusarek <nslusarek@gmx.net>,
	Alexander Popov <alex.popov@linux.com>,
	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: Re: [RFC PATCH v8 04/19] af_vsock: implement SEQPACKET receive loop
Date: Wed, 21 Apr 2021 10:37:32 +0200	[thread overview]
Message-ID: <20210421083732.hxlilatddifcokjx@steredhat> (raw)
In-Reply-To: <20210413124250.3400313-1-arseny.krasnov@kaspersky.com>

On Tue, Apr 13, 2021 at 03:42:47PM +0300, Arseny Krasnov wrote:
>This adds receive loop for SEQPACKET. It looks like receive loop for
>STREAM, but there is a little bit difference:
>1) It doesn't call notify callbacks.
>2) It doesn't care about 'SO_SNDLOWAT' and 'SO_RCVLOWAT' values, because
>   there is no sense for these values in SEQPACKET case.
>3) It waits until whole record is received or error is found during
>   receiving.
>4) It processes and sets 'MSG_TRUNC' flag.
>
>So to avoid extra conditions for two types of socket inside one loop, two
>independent functions were created.
>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
>v7 -> v8:
> - Length of message is now not returned by callback, it returns only
>   length of data read by each call.
> - Previous case, when EAGAIN is return and dequeue loop restarted now
>   removed(in this simplified version we consider that message could not
>   be corrupted).
> - MSG_TRUNC in input flags is now handled by callback.
>
> include/net/af_vsock.h   |  4 +++
> net/vmw_vsock/af_vsock.c | 66 +++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 69 insertions(+), 1 deletion(-)
>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index b1c717286993..5175f5a52ce1 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -135,6 +135,10 @@ struct vsock_transport {
> 	bool (*stream_is_active)(struct vsock_sock *);
> 	bool (*stream_allow)(u32 cid, u32 port);
>
>+	/* SEQ_PACKET. */
>+	ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
>+				     int flags, bool *msg_ready);
>+
> 	/* Notification. */
> 	int (*notify_poll_in)(struct vsock_sock *, size_t, bool *);
> 	int (*notify_poll_out)(struct vsock_sock *, size_t, bool *);
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index c4f6bfa1e381..d9fb4f9a3063 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1974,6 +1974,67 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
> 	return err;
> }
>
>+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;
>+	int err = 0;
>+	DEFINE_WAIT(wait);
>+
>+	vsk = vsock_sk(sk);
>+	transport = vsk->transport;
>+
>+	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
>+	msg_ready = false;
>+	record_len = 0;
>+
>+	while (1) {
>+		ssize_t tmp_record_len;

Maybe better a name like `partial_len`, `fragment_len`, or just `read`.

>+
>+		if (vsock_wait_data(sk, &wait, timeout, NULL, 0) <= 0) {
>+			/* In case of any loop break(timeout, signal
>+			 * interrupt or shutdown), we report user that
>+			 * nothing was copied.
>+			 */
>+			err = 0;
>+			break;
>+		}
>+
>+		tmp_record_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready);

I think we can avoid to pass 'flags' down to the transports.

We can require that seqpacket_dequeue() should always return the real 
size of the packet received, and then check below if 'MSG_TRUNC' was 
set...

>+
>+		if (tmp_record_len < 0) {
>+			err = -ENOMEM;
>+			break;
>+		}
>+
>+		record_len += tmp_record_len;
>+
>+		if (msg_ready)
>+			break;
>+	}
>+
>+	if (sk->sk_err)
>+		err = -sk->sk_err;
>+	else if (sk->sk_shutdown & RCV_SHUTDOWN)
>+		err = 0;
>+
>+	if (msg_ready && err == 0) {
>+		err = record_len;
>+
>+		/* Always set MSG_TRUNC if real length of packet is
>+		 * bigger than user's buffer.
>+		 */

...here:
		if (flags & MSG_TRUNC && record_len > len)

>+		if (record_len > len)
>+			msg->msg_flags |= MSG_TRUNC;
>+	}
>+
>+	return err;
>+}
>+
> static int
> vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> 			  int flags)
>@@ -2029,7 +2090,10 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> 		goto out;
> 	}
>
>-	err = __vsock_stream_recvmsg(sk, msg, len, flags);
>+	if (sk->sk_type == SOCK_STREAM)
>+		err = __vsock_stream_recvmsg(sk, msg, len, flags);
>+	else
>+		err = __vsock_seqpacket_recvmsg(sk, msg, len, flags);
>
> out:
> 	release_sock(sk);
>-- )
>2.25.1
>


  reply	other threads:[~2021-04-21  8:37 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 12:39 [RFC PATCH v8 00/19] virtio/vsock: introduce SOCK_SEQPACKET support Arseny Krasnov
2021-04-13 12:41 ` [RFC PATCH v8 01/19] af_vsock: update functions for connectible socket Arseny Krasnov
2021-04-13 12:42 ` [RFC PATCH v8 02/19] af_vsock: separate wait data loop Arseny Krasnov
2021-04-13 12:42 ` [RFC PATCH v8 03/19] af_vsock: separate receive " Arseny Krasnov
2021-04-13 12:42 ` [RFC PATCH v8 04/19] af_vsock: implement SEQPACKET receive loop Arseny Krasnov
2021-04-21  8:37   ` Stefano Garzarella [this message]
2021-04-21 14:47     ` Arseny Krasnov
2021-04-13 12:43 ` [RFC PATCH v8 05/19] af_vsock: implement send logic for SEQPACKET Arseny Krasnov
2021-04-13 12:43 ` [RFC PATCH v8 06/19] af_vsock: rest of SEQPACKET support Arseny Krasnov
2021-04-13 12:43 ` [RFC PATCH v8 07/19] af_vsock: update comments for stream sockets Arseny Krasnov
2021-04-13 12:43 ` [RFC PATCH v8 08/19] virtio/vsock: set packet's type in virtio_transport_send_pkt_info() Arseny Krasnov
2021-04-13 12:44 ` [RFC PATCH v8 09/19] virtio/vsock: simplify credit update function API Arseny Krasnov
2021-04-13 12:44 ` [RFC PATCH v8 10/19] virtio/vsock: defines and constants for SEQPACKET Arseny Krasnov
2021-04-13 12:44 ` [RFC PATCH v8 11/19] virtio/vsock: dequeue callback for SOCK_SEQPACKET Arseny Krasnov
2021-04-14  5:21   ` Arseny Krasnov
2021-04-21  8:56   ` Stefano Garzarella
2021-04-21 14:49     ` Arseny Krasnov
2021-04-13 12:45 ` [RFC PATCH v8 12/19] virtio/vsock: add SEQPACKET receive logic Arseny Krasnov
2021-04-13 12:45 ` [RFC PATCH v8 13/19] virtio/vsock: rest of SOCK_SEQPACKET support Arseny Krasnov
2021-04-21  9:12   ` Stefano Garzarella
2021-04-21 14:50     ` Arseny Krasnov
2021-04-13 12:45 ` [RFC PATCH v8 14/19] virtio/vsock: enable SEQPACKET for transport Arseny Krasnov
2021-04-21  9:22   ` Stefano Garzarella
2021-04-13 12:46 ` [RFC PATCH v8 15/19] vhost/vsock: " Arseny Krasnov
2021-04-21  9:31   ` Stefano Garzarella
2021-04-13 12:46 ` [RFC PATCH v8 16/19] vsock/loopback: " Arseny Krasnov
2021-04-21  9:34   ` Stefano Garzarella
2021-04-13 12:46 ` [RFC PATCH v8 17/19] vsock_test: add SOCK_SEQPACKET tests Arseny Krasnov
2021-04-21  9:35   ` Stefano Garzarella
2021-04-21 15:00     ` Arseny Krasnov
2021-04-13 12:47 ` [RFC PATCH v8 18/19] virtio/vsock: update trace event for SEQPACKET Arseny Krasnov
2021-04-13 12:47 ` [RFC PATCH v8 19/19] af_vsock: serialize writes to shared socket Arseny Krasnov
2021-04-14 10:51   ` Arseny Krasnov
2021-04-21  9:38     ` Stefano Garzarella
2021-04-21 15:02       ` Arseny Krasnov
2021-04-21  9:52 ` [RFC PATCH v8 00/19] virtio/vsock: introduce SOCK_SEQPACKET support Stefano Garzarella
2021-04-21 15:06   ` Arseny Krasnov
2021-04-22  8:46     ` Stefano Garzarella
2021-04-22  9:40       ` Arseny Krasnov
2021-04-22 10:02         ` Stefano Garzarella
2021-04-22 10:29           ` Arseny Krasnov
2021-04-22 10:48             ` Stefano Garzarella
2021-04-22 11:41               ` Arseny Krasnov

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