Re: [RFC PATCH v1 1/2] vsock: return errors other than -ENOMEM to socket

[Stefano Garzarella]

On Tue, Mar 28, 2023 at 01:42:19PM +0300, Arseniy Krasnov wrote:
> On 28.03.2023 12:42, Stefano Garzarella wrote:
> > I pressed send too early...
> >
> > CCing Bryan, Vishnu, and pv-drivers@xxxxxxxxxx
> >
> > On Tue, Mar 28, 2023 at 11:39 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > > On Sun, Mar 26, 2023 at 01:13:11AM +0300, Arseniy Krasnov wrote:
> > > > This removes behaviour, where error code returned from any transport
> > > > was always switched to ENOMEM. This works in the same way as:
> > > > commit
> > > > c43170b7e157 ("vsock: return errors other than -ENOMEM to socket"),
> > > > but for receive calls.
> > > >
> > > > Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> > > > ---
> > > > net/vmw_vsock/af_vsock.c | 4 ++--
> > > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > > > index 19aea7cba26e..9262e0b77d47 100644
> > > > --- a/net/vmw_vsock/af_vsock.c
> > > > +++ b/net/vmw_vsock/af_vsock.c
> > > > @@ -2007,7 +2007,7 @@ static int __vsock_stream_recvmsg(struct sock *sk, struct msghdr *msg,
> > > >
> > > >               read = transport->stream_dequeue(vsk, msg, len - copied, flags);
> > >
> > > In vmci_transport_stream_dequeue() vmci_qpair_peekv() and
> > > vmci_qpair_dequev() return VMCI_ERROR_* in case of errors.
> > >
> > > Maybe we should return -ENOMEM in vmci_transport_stream_dequeue() if
> > > those functions fail to keep the same behavior.
>
> Yes, seems i missed it, because several months ago we had similar question for send
> logic:
> https://www.spinics.net/lists/kernel/msg4611091.html
> And it was ok to not handle VMCI send path in this way. So i think current implementation
> for tx is a little bit buggy, because VMCI specific error from 'vmci_qpair_enquev()' is
> returned to af_vsock.c. I think error conversion must be added to VMCI transport for tx
> also.

Good point!

These are negative values, so there are no big problems, but I don't
know what the user expects in this case.

@Vishnu Do we want to return an errno to the user or a VMCI_ERROR_*?

In both cases I think we should do the same for both enqueue and
dequeue.

> Good thing is that Hyper-V uses general error codes.

Yeah!

Thanks,
Stefano

> Thanks, Arseniy
> > > CCing Bryan, Vishnu, and pv-drivers@xxxxxxxxxx
> > >
> > > The other transports seem okay to me.
> > >
> > > Thanks,
> > > Stefano
> > >
> > > >               if (read < 0) {
> > > > -                      err = -ENOMEM;
> > > > +                      err = read;
> > > >                       break;
> > > >               }
> > > >
> > > > @@ -2058,7 +2058,7 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
> > > >       msg_len = transport->seqpacket_dequeue(vsk, msg, flags);
> > > >
> > > >       if (msg_len < 0) {
> > > > -              err = -ENOMEM;
> > > > +              err = msg_len;
> > > >               goto out;
> > > >       }
> > > >
> > > > --
> > > > 2.25.1