Re: [PATCH 19/33] virtio_net: introduce virtnet_tx_reset()

From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Petr Machata" <petrm@nvidia.com>,
	"Menglong Dong" <imagedong@tencent.com>,
	"Maciej Fijalkowski" <maciej.fijalkowski@intel.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	netdev@vger.kernel.org,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Eric Dumazet" <edumazet@google.com>,
	"Kuniyuki Iwashima" <kuniyu@amazon.com>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
	"Jonathan Lemon" <jonathan.lemon@gmail.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	bpf@vger.kernel.org, "Paolo Abeni" <pabeni@redhat.com>,
	virtualization@lists.linux-foundation.org,
	"David S. Miller" <davem@davemloft.net>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>
Subject: Re: [PATCH 19/33] virtio_net: introduce virtnet_tx_reset()
Date: Fri, 3 Feb 2023 12:35:32 +0800	[thread overview]
Message-ID: <1675398932.095303-3-xuanzhuo@linux.alibaba.com> (raw)
In-Reply-To: <20230202121745-mutt-send-email-mst@kernel.org>

On Thu, 2 Feb 2023 12:23:56 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Thu, Feb 02, 2023 at 07:00:44PM +0800, Xuan Zhuo wrote:
> > Introduce virtnet_tx_reset() to release the buffers inside virtio ring.
> >
> > This is needed for xsk disable. When disable xsk, we need to relese the
>
> typo
>
> > buffer from xsk, so this function is needed.
> >
> > This patch reuse the virtnet_tx_resize.
>
> reuses
>
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
>
>
> > ---
> >  drivers/net/virtio/main.c       | 21 ++++++++++++++++++---
> >  drivers/net/virtio/virtio_net.h |  1 +
> >  2 files changed, 19 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> > index fb82035a0b7f..049a3bb9d88d 100644
> > --- a/drivers/net/virtio/main.c
> > +++ b/drivers/net/virtio/main.c
> > @@ -1806,8 +1806,8 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
> >  	return err;
> >  }
> >
> > -static int virtnet_tx_resize(struct virtnet_info *vi,
> > -			     struct send_queue *sq, u32 ring_num)
> > +static int __virtnet_tx_reset(struct virtnet_info *vi,
> > +			      struct send_queue *sq, u32 ring_num)
> >  {
> >  	bool running = netif_running(vi->dev);
> >  	struct netdev_queue *txq;
> > @@ -1833,7 +1833,11 @@ static int virtnet_tx_resize(struct virtnet_info *vi,
> >
> >  	__netif_tx_unlock_bh(txq);
> >
> > -	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
> > +	if (ring_num)
> > +		err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
> > +	else
> > +		err = virtqueue_reset(sq->vq, virtnet_sq_free_unused_buf);
> > +
> >  	if (err)
> >  		netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", qindex, err);
> >
>
> This __virtnet_tx_reset is a really weird API.
>
> Suggest just splitting the common parts:
>
> __virtnet_tx_pause
> __virtnet_tx_resume
>
> we can then implement virtnet_tx_resize and virtnet_tx_reset
> using these two.

Good idea.

Thanks.

>
>
> > @@ -1847,6 +1851,17 @@ static int virtnet_tx_resize(struct virtnet_info *vi,
> >  	return err;
> >  }
> >
> > +static int virtnet_tx_resize(struct virtnet_info *vi,
> > +			     struct send_queue *sq, u32 ring_num)
> > +{
> > +	return __virtnet_tx_reset(vi, sq, ring_num);
> > +}
> > +
> > +int virtnet_tx_reset(struct virtnet_info *vi, struct send_queue *sq)
> > +{
> > +	return __virtnet_tx_reset(vi, sq, 0);
> > +}
> > +
> >  /*
> >   * Send command via the control virtqueue and check status.  Commands
> >   * supported by the hypervisor, as indicated by feature bits, should
> > diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
> > index af3e7e817f9e..b46f083a630a 100644
> > --- a/drivers/net/virtio/virtio_net.h
> > +++ b/drivers/net/virtio/virtio_net.h
> > @@ -273,4 +273,5 @@ int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
> >  			struct net_device *dev,
> >  			unsigned int *xdp_xmit,
> >  			struct virtnet_rq_stats *stats);
> > +int virtnet_tx_reset(struct virtnet_info *vi, struct send_queue *sq);
> >  #endif
> > --
> > 2.32.0.3.g01195cf9f
>
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