On Sat, May 08, 2021 at 07:33:14PM +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@xxxxxxxxxxxxx>
---
v8 -> v9:
1) 'tmp_record_len' renamed to 'fragment_len'.
2) MSG_TRUNC handled in af_vsock.c instead of transport.
3) 'flags' still passed to transport for MSG_PEEK support.
Ah, right I see, sorry for the wrong suggestion to remove it.
include/net/af_vsock.h | 4 +++
net/vmw_vsock/af_vsock.c | 72 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 75 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..78b9af545ca8 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1974,6 +1974,73 @@ 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 fragment_len;
+
+ 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;
+ }
+
+ fragment_len = transport->seqpacket_dequeue(vsk, msg, flags, &msg_ready);
+
So, IIUC, seqpacket_dequeue() must return the real length,
and not the bytes copied, right?
I'm not sure virtio_transport_seqpacket_do_dequeue() is doing that.
I'll post a comment on that patch.
+ if (fragment_len < 0) {
+ err = -ENOMEM;
+ break;
+ }
+
+ record_len += fragment_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) {
+ /* User sets MSG_TRUNC, so return real length of
+ * packet.
+ */
+ if (flags & MSG_TRUNC)
+ err = record_len;
+ else
+ err = len - msg->msg_iter.count;
I think is better to use msg_data_left(msg) instead of accessing fields.
+
+ /* Always set MSG_TRUNC if real length of packet is
+ * bigger than user's buffer.
+ */
+ 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 +2096,10 @@ 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
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