netdev - Re: [PATCH net-next v2 14/21] virtio_net: xsk: tx: virtnet_free_old

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Message-ID: <20231109065912-mutt-send-email-mst@kernel.org>
Date: Thu, 9 Nov 2023 06:59:48 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: 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>,
	Jason Wang <jasowang@...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 net-next v2 14/21] virtio_net: xsk: tx:
 virtnet_free_old_xmit() distinguishes xsk buffer

On Thu, Nov 09, 2023 at 07:16:08PM +0800, Xuan Zhuo wrote:
> On Thu, 9 Nov 2023 06:11:49 -0500, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > On Tue, Nov 07, 2023 at 11:12:20AM +0800, Xuan Zhuo wrote:
> > > virtnet_free_old_xmit distinguishes three type ptr(skb, xdp frame, xsk
> > > buffer) by the last bits of the pointer.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> > > ---
> > >  drivers/net/virtio/virtio_net.h | 18 ++++++++++++++++--
> > >  drivers/net/virtio/xsk.h        |  5 +++++
> > >  2 files changed, 21 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
> > > index a431a2c1ee47..a13d6d301fdb 100644
> > > --- a/drivers/net/virtio/virtio_net.h
> > > +++ b/drivers/net/virtio/virtio_net.h
> > > @@ -225,6 +225,11 @@ struct virtnet_info {
> > >  	struct failover *failover;
> > >  };
> > >
> > > +static inline bool virtnet_is_skb_ptr(void *ptr)
> > > +{
> > > +	return !((unsigned long)ptr & VIRTIO_XMIT_DATA_MASK);
> > > +}
> > > +
> > >  static inline bool virtnet_is_xdp_frame(void *ptr)
> > >  {
> > >  	return (unsigned long)ptr & VIRTIO_XDP_FLAG;
> > > @@ -235,6 +240,8 @@ static inline struct xdp_frame *virtnet_ptr_to_xdp(void *ptr)
> > >  	return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
> > >  }
> > >
> > > +static inline u32 virtnet_ptr_to_xsk(void *ptr);
> > > +
> >
> > I don't understand why you need this here.
> 
> The below function virtnet_free_old_xmit needs this.
> 
> Thanks.

I don't understand why is virtnet_free_old_xmit inline, either.

> >
> >
> > >  static inline void *virtnet_sq_unmap(struct virtnet_sq *sq, void *data)
> > >  {
> > >  	struct virtnet_sq_dma *next, *head;
> > > @@ -261,11 +268,12 @@ static inline void *virtnet_sq_unmap(struct virtnet_sq *sq, void *data)
> > >  static inline void virtnet_free_old_xmit(struct virtnet_sq *sq, bool in_napi,
> > >  					 u64 *bytes, u64 *packets)
> > >  {
> > > +	unsigned int xsknum = 0;
> > >  	unsigned int len;
> > >  	void *ptr;
> > >
> > >  	while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> > > -		if (!virtnet_is_xdp_frame(ptr)) {
> > > +		if (virtnet_is_skb_ptr(ptr)) {
> > >  			struct sk_buff *skb;
> > >
> > >  			if (sq->do_dma)
> > > @@ -277,7 +285,7 @@ static inline void virtnet_free_old_xmit(struct virtnet_sq *sq, bool in_napi,
> > >
> > >  			*bytes += skb->len;
> > >  			napi_consume_skb(skb, in_napi);
> > > -		} else {
> > > +		} else if (virtnet_is_xdp_frame(ptr)) {
> > >  			struct xdp_frame *frame;
> > >
> > >  			if (sq->do_dma)
> > > @@ -287,9 +295,15 @@ static inline void virtnet_free_old_xmit(struct virtnet_sq *sq, bool in_napi,
> > >
> > >  			*bytes += xdp_get_frame_len(frame);
> > >  			xdp_return_frame(frame);
> > > +		} else {
> > > +			*bytes += virtnet_ptr_to_xsk(ptr);
> > > +			++xsknum;
> > >  		}
> > >  		(*packets)++;
> > >  	}
> > > +
> > > +	if (xsknum)
> > > +		xsk_tx_completed(sq->xsk.pool, xsknum);
> > >  }
> > >
> > >  static inline bool virtnet_is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
> > > diff --git a/drivers/net/virtio/xsk.h b/drivers/net/virtio/xsk.h
> > > index 1bd19dcda649..7ebc9bda7aee 100644
> > > --- a/drivers/net/virtio/xsk.h
> > > +++ b/drivers/net/virtio/xsk.h
> > > @@ -14,6 +14,11 @@ static inline void *virtnet_xsk_to_ptr(u32 len)
> > >  	return (void *)(p | VIRTIO_XSK_FLAG);
> > >  }
> > >
> > > +static inline u32 virtnet_ptr_to_xsk(void *ptr)
> > > +{
> > > +	return ((unsigned long)ptr) >> VIRTIO_XSK_FLAG_OFFSET;
> > > +}
> > > +
> > >  int virtnet_xsk_pool_setup(struct net_device *dev, struct netdev_bpf *xdp);
> > >  bool virtnet_xsk_xmit(struct virtnet_sq *sq, struct xsk_buff_pool *pool,
> > >  		      int budget);
> > > --
> > > 2.32.0.3.g01195cf9f
> >
> >