On Fri, Jan 29, 2021 at 09:28:49AM +0300, Arseny Krasnov wrote:
On 28.01.2021 19:55, Stefano Garzarella wrote:
On Mon, Jan 25, 2021 at 02:12:36PM +0300, Arseny Krasnov wrote:
This adds receive loop for SEQPACKET. It looks like receive loop for
SEQPACKET, 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>
---
include/net/af_vsock.h | 5 ++
net/vmw_vsock/af_vsock.c | 102 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 106 insertions(+), 1 deletion(-)
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index b1c717286993..46073842d489 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -135,6 +135,11 @@ struct vsock_transport {
bool (*stream_is_active)(struct vsock_sock *);
bool (*stream_allow)(u32 cid, u32 port);
+ /* SEQ_PACKET. */
+ size_t (*seqpacket_seq_get_len)(struct vsock_sock *);
+ ssize_t (*seqpacket_dequeue)(struct vsock_sock *, struct msghdr *,
+ size_t len, int flags);
+
/* 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 524df8fc84cd..3b266880b7c8 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2006,7 +2006,107 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
size_t len, int flags)
{
- return -1;
+ const struct vsock_transport *transport;
+ const struct iovec *orig_iov;
+ unsigned long orig_nr_segs;
+ ssize_t dequeued_total = 0;
+ struct vsock_sock *vsk;
+ size_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->msg_flags &= ~MSG_EOR;
Maybe add a comment about why we need to clear MSG_EOR.
+ orig_nr_segs = msg->msg_iter.nr_segs;
+ orig_iov = msg->msg_iter.iov;
+
+ while (1) {
+ ssize_t dequeued;
+ s64 ready;
+
+ prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+ ready = vsock_stream_has_data(vsk);
+
+ if (ready == 0) {
+ if (vsock_wait_data(sk, &wait, timeout, NULL, 0)) {
+ /* In case of any loop break(timeout, signal
+ * interrupt or shutdown), we report user that
+ * nothing was copied.
+ */
+ dequeued_total = 0;
+ break;
+ }
+ continue;
+ }
+
+ finish_wait(sk_sleep(sk), &wait);
+
+ if (ready < 0) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ if (dequeued_total == 0) {
+ record_len =
+ transport->seqpacket_seq_get_len(vsk);
+
+ if (record_len == 0)
+ continue;
+ }
+
+ /* 'msg_iter.count' is number of unused bytes in iov.
+ * On every copy to iov iterator it is decremented at
+ * size of data.
+ */
+ dequeued = transport->seqpacket_dequeue(vsk, msg,
+ msg->msg_iter.count, flags);
^
Is this needed or 'msg' can be
used in the transport?
Yes, right
+
+ if (dequeued < 0) {
+ dequeued_total = 0;
+
+ if (dequeued == -EAGAIN) {
+ iov_iter_init(&msg->msg_iter, READ,
+ orig_iov, orig_nr_segs,
+ len);
+ msg->msg_flags &= ~MSG_EOR;
+ continue;
Why we need to reset MSG_EOR here?
Because if previous attempt to receive record was failed, but
MSG_EOR was set, so we clear it for next attempt to get record
Yes, I saw later when I looked at the implementation in the transport.
Maybe better to put a comment saying that seqpacket_dequeue() can set
that flag.
Thanks,
Stefano
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