Re: [PATCH 2/6] vsock: return errors other than -ENOMEM to socket

Bobby Eshleman
2022-09-26T21:31:01Z

On Mon, Sep 26, 2022 at 03:21:45PM +0200, Stefano Garzarella wrote:
> On Mon, Aug 15, 2022 at 10:56:05AM -0700, Bobby Eshleman wrote:
> > This commit allows vsock implementations to return errors
> > to the socket layer other than -ENOMEM. One immediate effect
> > of this is that upon the sk_sndbuf threshold being reached -EAGAIN
> > will be returned and userspace may throttle appropriately.
> >
> > Resultingly, a known issue with uperf is resolved[1].
> >
> > Additionally, to preserve legacy behavior for non-virtio
> > implementations, hyperv/vmci force errors to be -ENOMEM so that behavior
> > is unchanged.
> >
> > [1]: https://gitlab.com/vsock/vsock/-/issues/1
> >
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
> > ---
> > include/linux/virtio_vsock.h | 3 +++
> > net/vmw_vsock/af_vsock.c | 3 ++-
> > net/vmw_vsock/hyperv_transport.c | 2 +-
> > net/vmw_vsock/virtio_transport_common.c | 3 ---
> > net/vmw_vsock/vmci_transport.c | 9 ++++++++-
> > 5 files changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> > index 17ed01466875..9a37eddbb87a 100644
> > --- a/include/linux/virtio_vsock.h
> > +++ b/include/linux/virtio_vsock.h
> > @@ -8,6 +8,9 @@
> > #include <net/sock.h>
> > #include <net/af_vsock.h>
> >
> > +/* Threshold for detecting small packets to copy */
> > +#define GOOD_COPY_LEN 128
> > +
>
> This change seems unrelated.
>
> Please move it in the patch where you need this.
> Maybe it's better to add a prefix if we move it in an header file (e.g.
> VIRTIO_VSOCK_...).
>
> Thanks,
> Stefano
>

Oh yes, definitely.

Thanks,
Bobby

> > enum virtio_vsock_metadata_flags {
> > VIRTIO_VSOCK_METADATA_FLAGS_REPLY = BIT(0),
> > VIRTIO_VSOCK_METADATA_FLAGS_TAP_DELIVERED = BIT(1),
> > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > index e348b2d09eac..1893f8aafa48 100644
> > --- a/net/vmw_vsock/af_vsock.c
> > +++ b/net/vmw_vsock/af_vsock.c
> > @@ -1844,8 +1844,9 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> > written = transport->stream_enqueue(vsk,
> > msg, len - total_written);
> > }
> > +
> > if (written < 0) {
> > - err = -ENOMEM;
> > + err = written;
> > goto out_err;
> > }
> >
> > diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> > index fd98229e3db3..e99aea571f6f 100644
> > --- a/net/vmw_vsock/hyperv_transport.c
> > +++ b/net/vmw_vsock/hyperv_transport.c
> > @@ -687,7 +687,7 @@ static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
> > if (bytes_written)
> > ret = bytes_written;
> > kfree(send_buf);
> > - return ret;
> > + return ret < 0 ? -ENOMEM : ret;
> > }
> >
> > static s64 hvs_stream_has_data(struct vsock_sock *vsk)
> > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> > index 920578597bb9..d5780599fe93 100644
> > --- a/net/vmw_vsock/virtio_transport_common.c
> > +++ b/net/vmw_vsock/virtio_transport_common.c
> > @@ -23,9 +23,6 @@
> > /* How long to wait for graceful shutdown of a connection */
> > #define VSOCK_CLOSE_TIMEOUT (8 * HZ)
> >
> > -/* Threshold for detecting small packets to copy */
> > -#define GOOD_COPY_LEN 128
> > -
> > static const struct virtio_transport *
> > virtio_transport_get_ops(struct vsock_sock *vsk)
> > {
> > diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> > index b14f0ed7427b..c927a90dc859 100644
> > --- a/net/vmw_vsock/vmci_transport.c
> > +++ b/net/vmw_vsock/vmci_transport.c
> > @@ -1838,7 +1838,14 @@ static ssize_t vmci_transport_stream_enqueue(
> > struct msghdr *msg,
> > size_t len)
> > {
> > - return vmci_qpair_enquev(vmci_trans(vsk)->qpair, msg, len, 0);
> > + int err;
> > +
> > + err = vmci_qpair_enquev(vmci_trans(vsk)->qpair, msg, len, 0);
> > +
> > + if (err < 0)
> > + err = -ENOMEM;
> > +
> > + return err;
> > }
> >
> > static s64 vmci_transport_stream_has_data(struct vsock_sock *vsk)
> > --
> > 2.35.1
> >
>
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