netdev - Re: [PATCH 00/16] virtio-net: split virtio-net.c

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Message-ID: <CACGkMEt2M3zaytjOmhTuSx6wnerZBrVoQxgbUuAv0WmUu50Hiw@mail.gmail.com>
Date:   Fri, 31 Mar 2023 15:35:14 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        virtualization@...ts.linux-foundation.org, bpf@...r.kernel.org
Subject: Re: [PATCH 00/16] virtio-net: split virtio-net.c

On Fri, Mar 31, 2023 at 3:31 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> On Thu, 30 Mar 2023 02:17:43 -0400, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > On Tue, Mar 28, 2023 at 05:28:31PM +0800, Xuan Zhuo wrote:
> > > Considering the complexity of virtio-net.c and the new features we want
> > > to add, it is time to split virtio-net.c into multiple independent
> > > module files.
> > >
> > > This is beneficial to the maintenance and adding new functions.
> > >
> > > And AF_XDP support will be added later, then a separate xsk.c file will
> > > be added.
> > >
> > > This patchset split virtio-net.c into these parts:
> > >
> > > * virtnet.c:         virtio net device ops (napi, tx, rx, device ops, ...)
> > > * virtnet_common.c:  virtio net common code
> > > * virtnet_ethtool.c: virtio net ethtool callbacks
> > > * virtnet_ctrl.c:    virtio net ctrl queue command APIs
> > > * virtnet_virtio.c:  virtio net virtio callbacks/ops (driver register, virtio probe, virtio free, ...)
> > >
> > > Please review.
> > >
> > > Thanks.
> >
> >
> > I don't feel this is an improvement as presented, will need more work
> > to make code placement more logical.
>
> Yes, this does need some time and energy. But I think this always need to do,
> just when to do it. I think it is currently an opportunity.
>
>
> >
> > For example where do I find code to update rq stats?
> > Rx data path should be virtnet.c?
> > No it's in virtnet_ethtool.c because rq stats can be
> > accessed by ethtool.
>
> That's what I do.
>
> > A bunch of stuff seems to be in headers just because of technicalities.
> > virtio common seems to be a dumping ground with no guiding principle at
> > all.
>
> Yes, I agree, with the development of time, common will indeed become a dumping
> group. This is something we should pay attention to after this.
>
>
> > drivers/net/virtio/virtnet_virtio.c is weird with
> > virt repeated three times in the path.
>
> Any good idea.
>
> >
> > These things only get murkier with time, at the point of reorg
> > I would expect very logical placement, since
> > without clear guiding rule finding where something is becomes harder but
> > more importantly we'll now get endless heartburn about where does each new
> > function go.
> >
> >
> > The reorg is unfortunately not free - for example git log --follow will
> > no longer easily match virtio because --follow works with exactly one
> > path.
>
> One day we will face this problem.
>
> > It's now also extra work to keep headers self-consistent.
>
> Can we make it simpler, first complete the split.
>
>
> > So it better be a big improvement to be worth it.
>
>
> Or about split, do you have any better thoughts? Or do you think we have always
> been like this and make Virtio-Net more and more complicated?

My feeling is that maybe it's worth it to start using a separate file
for xsk support.

Thanks

>
>
> Thanks.
>
> >
> >
> >
> >
> > > Xuan Zhuo (16):
> > >   virtio_net: add a separate directory for virtio-net
> > >   virtio_net: move struct to header file
> > >   virtio_net: add prefix to the struct inside header file
> > >   virtio_net: separating cpu-related funs
> > >   virtio_net: separate virtnet_ctrl_set_queues()
> > >   virtio_net: separate virtnet_ctrl_set_mac_address()
> > >   virtio_net: remove lock from virtnet_ack_link_announce()
> > >   virtio_net: separating the APIs of cq
> > >   virtio_net: introduce virtnet_rq_update_stats()
> > >   virtio_net: separating the funcs of ethtool
> > >   virtio_net: introduce virtnet_dev_rx_queue_group()
> > >   virtio_net: introduce virtnet_get_netdev()
> > >   virtio_net: prepare for virtio
> > >   virtio_net: move virtnet_[en/dis]able_delayed_refill to header file
> > >   virtio_net: add APIs to register/unregister virtio driver
> > >   virtio_net: separating the virtio code
> > >
> > >  MAINTAINERS                                   |    2 +-
> > >  drivers/net/Kconfig                           |    8 +-
> > >  drivers/net/Makefile                          |    2 +-
> > >  drivers/net/virtio/Kconfig                    |   11 +
> > >  drivers/net/virtio/Makefile                   |   10 +
> > >  .../net/{virtio_net.c => virtio/virtnet.c}    | 2368 ++---------------
> > >  drivers/net/virtio/virtnet.h                  |  213 ++
> > >  drivers/net/virtio/virtnet_common.c           |  138 +
> > >  drivers/net/virtio/virtnet_common.h           |   14 +
> > >  drivers/net/virtio/virtnet_ctrl.c             |  272 ++
> > >  drivers/net/virtio/virtnet_ctrl.h             |   45 +
> > >  drivers/net/virtio/virtnet_ethtool.c          |  578 ++++
> > >  drivers/net/virtio/virtnet_ethtool.h          |    8 +
> > >  drivers/net/virtio/virtnet_virtio.c           |  880 ++++++
> > >  drivers/net/virtio/virtnet_virtio.h           |    8 +
> > >  15 files changed, 2366 insertions(+), 2191 deletions(-)
> > >  create mode 100644 drivers/net/virtio/Kconfig
> > >  create mode 100644 drivers/net/virtio/Makefile
> > >  rename drivers/net/{virtio_net.c => virtio/virtnet.c} (50%)
> > >  create mode 100644 drivers/net/virtio/virtnet.h
> > >  create mode 100644 drivers/net/virtio/virtnet_common.c
> > >  create mode 100644 drivers/net/virtio/virtnet_common.h
> > >  create mode 100644 drivers/net/virtio/virtnet_ctrl.c
> > >  create mode 100644 drivers/net/virtio/virtnet_ctrl.h
> > >  create mode 100644 drivers/net/virtio/virtnet_ethtool.c
> > >  create mode 100644 drivers/net/virtio/virtnet_ethtool.h
> > >  create mode 100644 drivers/net/virtio/virtnet_virtio.c
> > >  create mode 100644 drivers/net/virtio/virtnet_virtio.h
> > >
> > > --
> > > 2.32.0.3.g01195cf9f
> >
>