Re: [RFC PATCH v4 03/17] af_vsock: separate receive data loop

From: Stefano Garzarella
Date: Thu Feb 11 2021 - 06:58:34 EST


On Sun, Feb 07, 2021 at 06:15:05PM +0300, Arseny Krasnov wrote:
This moves STREAM specific data receive logic to dedicated function:
'__vsock_stream_recvmsg()', while checks that will be same for both
types of socket are in shared function: 'vsock_connectible_recvmsg()'.

Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
---
net/vmw_vsock/af_vsock.c | 117 +++++++++++++++++++++++----------------
1 file changed, 68 insertions(+), 49 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 38927695786f..66c8a932f49b 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1898,65 +1898,22 @@ static int vsock_wait_data(struct sock *sk, struct wait_queue_entry *wait,
return err;
}

-static int
-vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
- int flags)
+static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int flags)
{
- struct sock *sk;
- struct vsock_sock *vsk;
+ struct vsock_transport_recv_notify_data recv_data;
const struct vsock_transport *transport;
- int err;
- size_t target;
+ struct vsock_sock *vsk;
ssize_t copied;
+ size_t target;
long timeout;
- struct vsock_transport_recv_notify_data recv_data;
+ int err;

DEFINE_WAIT(wait);

- sk = sock->sk;
vsk = vsock_sk(sk);
- err = 0;
-
- lock_sock(sk);
-
transport = vsk->transport;

- if (!transport || sk->sk_state != TCP_ESTABLISHED) {
- /* Recvmsg is supposed to return 0 if a peer performs an
- * orderly shutdown. Differentiate between that case and when a
- * peer has not connected or a local shutdown occured with the
- * SOCK_DONE flag.
- */
- if (sock_flag(sk, SOCK_DONE))
- err = 0;
- else
- err = -ENOTCONN;
-
- goto out;
- }
-
- if (flags & MSG_OOB) {
- err = -EOPNOTSUPP;
- goto out;
- }
-
- /* We don't check peer_shutdown flag here since peer may actually shut
- * down, but there can be data in the queue that a local socket can
- * receive.
- */
- if (sk->sk_shutdown & RCV_SHUTDOWN) {
- err = 0;
- goto out;
- }
-
- /* It is valid on Linux to pass in a zero-length receive buffer. This
- * is not an error. We may as well bail out now.
- */
- if (!len) {
- err = 0;
- goto out;
- }
-
/* We must not copy less than target bytes into the user's buffer
* before returning successfully, so we wait for the consume queue to
* have that much data to consume before dequeueing. Note that this

At the end of __vsock_stream_recvmsg() you are calling release_sock(sk) and it's wrong since we are releasing it in vsock_connectible_recvmsg().

Please fix it.

@@ -2020,6 +1977,68 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
return err;
}

+static int
+vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+ int flags)
+{
+ struct sock *sk;
+ struct vsock_sock *vsk;
+ const struct vsock_transport *transport;
+ int err;
+
+ DEFINE_WAIT(wait);
+
+ sk = sock->sk;
+ vsk = vsock_sk(sk);
+ err = 0;
+
+ lock_sock(sk);
+
+ transport = vsk->transport;
+
+ if (!transport || sk->sk_state != TCP_ESTABLISHED) {
+ /* Recvmsg is supposed to return 0 if a peer performs an
+ * orderly shutdown. Differentiate between that case and when a
+ * peer has not connected or a local shutdown occurred with the
+ * SOCK_DONE flag.
+ */
+ if (sock_flag(sk, SOCK_DONE))
+ err = 0;
+ else
+ err = -ENOTCONN;
+
+ goto out;
+ }
+
+ if (flags & MSG_OOB) {
+ err = -EOPNOTSUPP;
+ goto out;
+ }
+
+ /* We don't check peer_shutdown flag here since peer may actually shut
+ * down, but there can be data in the queue that a local socket can
+ * receive.
+ */
+ if (sk->sk_shutdown & RCV_SHUTDOWN) {
+ err = 0;
+ goto out;
+ }
+
+ /* It is valid on Linux to pass in a zero-length receive buffer. This
+ * is not an error. We may as well bail out now.
+ */
+ if (!len) {
+ err = 0;
+ goto out;
+ }
+
+ err = __vsock_stream_recvmsg(sk, msg, len, flags);
+
+out:
+ release_sock(sk);
+ return err;
+}
+

The rest of the patch LGTM.

Stefano