[RFC PATCH v3 02/13] af_vsock: prepare 'vsock_connectible_recvmsg()'

Arseny Krasnov
2021-01-25T13:39:23Z

This prepares 'vsock_connectible_recvmg()' to call SEQPACKET receive
loop:
1) Some shared check left in this function, then socket type
specific receive loop is called.
2) Stream receive loop is moved to separate function.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
net/vmw_vsock/af_vsock.c | 242 ++++++++++++++++++++++-----------------
1 file changed, 138 insertions(+), 104 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index c9ce57db9554..524df8fc84cd 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1858,65 +1858,69 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
return vsock_connectible_sendmsg(sock, msg, len);
}

-
-static int
-vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
- int flags)
+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)
{
- struct sock *sk;
+ int err = 0;
struct vsock_sock *vsk;
const struct vsock_transport *transport;
- int err;
- size_t target;
- ssize_t copied;
- long timeout;
- struct vsock_transport_recv_notify_data recv_data;
-
- DEFINE_WAIT(wait);

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

+ if (sk->sk_err != 0 ||
+ (sk->sk_shutdown & RCV_SHUTDOWN) ||
+ (vsk->peer_shutdown & SEND_SHUTDOWN)) {
+ err = -1;
goto out;
}
-
- if (flags & MSG_OOB) {
- err = -EOPNOTSUPP;
+ /* Don't wait for non-blocking sockets. */
+ if (timeout == 0) {
+ err = -EAGAIN;
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;
+ if (recv_data) {
+ err = transport->notify_recv_pre_block(vsk, target, recv_data);
+ if (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;
+ release_sock(sk);
+ timeout = schedule_timeout(timeout);
+ lock_sock(sk);
+
+ if (signal_pending(current)) {
+ err = sock_intr_errno(timeout);
+ goto out;
+ } else if (timeout == 0) {
+ err = -EAGAIN;
goto out;
}

+out:
+ finish_wait(sk_sleep(sk), wait);
+ return err;
+}
+
+static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int flags)
+{
+ struct vsock_transport_recv_notify_data recv_data;
+ const struct vsock_transport *transport;
+ struct vsock_sock *vsk;
+ ssize_t copied;
+ size_t target;
+ long timeout;
+ int err;
+
+ DEFINE_WAIT(wait);
+
+ vsk = vsock_sk(sk);
+ transport = vsk->transport;
+
/* 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
@@ -1937,85 +1941,53 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,

while (1) {
+ ssize_t read;
s64 ready;

prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
ready = vsock_stream_has_data(vsk);

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);
+ if (vsock_wait_data(sk, &wait, timeout, &recv_data, target))
break;
- }
- } else {
- ssize_t read;
+ continue;
+ }

- finish_wait(sk_sleep(sk), &wait);
+ 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.
- */
+ 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 = -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);

- read = transport->stream_dequeue(
- vsk, msg,
- len - copied, flags);
- if (read < 0) {
- err = -ENOMEM;
- break;
- }
+ if (read < 0) {
+ err = -ENOMEM;
+ break;
+ }

- copied += read;
+ copied += read;

- err = transport->notify_recv_post_dequeue(
- vsk, target, read,
+ err = transport->notify_recv_post_dequeue(vsk,
+ target, read,
!(flags & MSG_PEEK), &recv_data);
- if (err < 0)
- goto out;
+ 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)
@@ -2031,6 +2003,68 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
return err;
}

+static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int flags)
+{
+ return -1;
+}
+
+static int
+vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+ int flags)
+{
+ const struct vsock_transport *transport;
+ struct vsock_sock *vsk;
+ struct sock *sk;
+ int err = 0;
+
+ sk = sock->sk;
+
+ lock_sock(sk);
+
+ vsk = vsock_sk(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 = -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)
+ 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)
+ goto out;
+
+ 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);
+ return err;
+}
+
static int
vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
--
2.25.1