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

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Message-ID: <20231109061056-mutt-send-email-mst@kernel.org>
Date: Thu, 9 Nov 2023 06:11:49 -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 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.


>  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