Re: [RFC PATCH v7 05/22] af_vsock: separate wait space loop

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>,
	Colin Ian King <colin.king@canonical.com>,
	Andra Paraschiv <andraprs@amazon.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 v7 05/22] af_vsock: separate wait space loop
Date: Thu, 25 Mar 2021 10:37:36 +0100	[thread overview]
Message-ID: <20210325093736.h43s47ylrxcjd2qd@steredhat> (raw)
In-Reply-To: <20210323131026.2460194-1-arseny.krasnov@kaspersky.com>

On Tue, Mar 23, 2021 at 04:10:23PM +0300, Arseny Krasnov wrote:
>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 | 99 +++++++++++++++++++++++++---------------
> 2 files changed, 63 insertions(+), 38 deletions(-)

I had already reviewed this one as well and it doesn't seem to have 
changed :-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index 74ac8a4c4168..7232f6c42a36 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -204,6 +204,8 @@ 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 fa0c37f97330..617ffe42693d 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1692,6 +1692,65 @@ 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)
> {
>@@ -1699,10 +1758,8 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 	struct vsock_sock *vsk;
> 	const struct vsock_transport *transport;
> 	ssize_t total_written;
>-	long timeout;
> 	int err;
> 	struct vsock_transport_send_notify_data send_data;
>-	DEFINE_WAIT_FUNC(wait, woken_wake_function);
>
> 	sk = sock->sk;
> 	vsk = vsock_sk(sk);
>@@ -1740,9 +1797,6 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 		goto out;
> 	}
>
>-	/* Wait for room in the produce queue to enqueue our user's data. */
>-	timeout = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
>-
> 	err = transport->notify_send_init(vsk, &send_data);
> 	if (err < 0)
> 		goto out;
>@@ -1750,39 +1804,8 @@ 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
>