Subject: Re: [PATCH net-next v2 14/18] xsk: make xsk_buff_add_frag really add a frag via __xdp_buff_add_frag()

From: Maciej Fijalkowski <[email-masked]>
Date: Thu, 17 Oct 2024 15:04:25 +0200

On Tue, Oct 15, 2024 at 04:53:46PM +0200, Alexander Lobakin wrote:
> Currently, xsk_buff_add_frag() only adds a frag to the pool linked list,
> not doing anything with the &xdp_buff. The drivers do that manually and
> the logic is the same.
> Make it really add an skb frag, just like xdp_buff_add_frag() does that,
> and freeing frags on error if needed. This allows to remove repeating
> code from i40e and ice and not add the same code again and again.
> 
> Signed-off-by: Alexander Lobakin <[email-masked]>

Acked-by: Maciej Fijalkowski <[email-masked]>

Me gusta.

> ---
>  include/net/xdp_sock_drv.h                 | 18 ++++++++++--
>  drivers/net/ethernet/intel/i40e/i40e_xsk.c | 30 ++------------------
>  drivers/net/ethernet/intel/ice/ice_xsk.c   | 32 ++--------------------
>  3 files changed, 20 insertions(+), 60 deletions(-)
> 
> diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
> index f3175a5d28f7..6aae95b83645 100644
> --- a/include/net/xdp_sock_drv.h
> +++ b/include/net/xdp_sock_drv.h
> @@ -136,11 +136,21 @@ static inline void xsk_buff_free(struct xdp_buff *xdp)
>  	xp_free(xskb);
>  }
>  
> -static inline void xsk_buff_add_frag(struct xdp_buff *xdp)
> +static inline bool xsk_buff_add_frag(struct xdp_buff *head,
> +				     struct xdp_buff *xdp)
>  {
> -	struct xdp_buff_xsk *frag = container_of(xdp, struct xdp_buff_xsk, xdp);
> +	const void *data = xdp->data;
> +	struct xdp_buff_xsk *frag;
> +
> +	if (!__xdp_buff_add_frag(head, virt_to_page(data),
> +				 offset_in_page(data), xdp->data_end - data,
> +				 xdp->frame_sz, false))
> +		return false;
>  
> +	frag = container_of(xdp, struct xdp_buff_xsk, xdp);
>  	list_add_tail(&frag->list_node, &frag->pool->xskb_list);
> +
> +	return true;
>  }
>  
>  static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
> @@ -357,8 +367,10 @@ static inline void xsk_buff_free(struct xdp_buff *xdp)
>  {
>  }
>  
> -static inline void xsk_buff_add_frag(struct xdp_buff *xdp)
> +static inline bool xsk_buff_add_frag(struct xdp_buff *head,
> +				     struct xdp_buff *xdp)
>  {
> +	return false;
>  }
>  
>  static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> index 4e885df789ef..e28f1905a4a0 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> @@ -395,32 +395,6 @@ static void i40e_handle_xdp_result_zc(struct i40e_ring *rx_ring,
>  	WARN_ON_ONCE(1);
>  }
>  
> -static int
> -i40e_add_xsk_frag(struct i40e_ring *rx_ring, struct xdp_buff *first,
> -		  struct xdp_buff *xdp, const unsigned int size)
> -{
> -	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(first);
> -
> -	if (!xdp_buff_has_frags(first)) {
> -		sinfo->nr_frags = 0;
> -		sinfo->xdp_frags_size = 0;
> -		xdp_buff_set_frags_flag(first);
> -	}
> -
> -	if (unlikely(sinfo->nr_frags == MAX_SKB_FRAGS)) {
> -		xsk_buff_free(first);
> -		return -ENOMEM;
> -	}
> -
> -	__skb_fill_page_desc_noacc(sinfo, sinfo->nr_frags++,
> -				   virt_to_page(xdp->data_hard_start),
> -				   XDP_PACKET_HEADROOM, size);
> -	sinfo->xdp_frags_size += size;
> -	xsk_buff_add_frag(xdp);
> -
> -	return 0;
> -}
> -
>  /**
>   * i40e_clean_rx_irq_zc - Consumes Rx packets from the hardware ring
>   * @rx_ring: Rx ring
> @@ -486,8 +460,10 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget)
>  
>  		if (!first)
>  			first = bi;
> -		else if (i40e_add_xsk_frag(rx_ring, first, bi, size))
> +		else if (!xsk_buff_add_frag(first, bi)) {
> +			xsk_buff_free(first);
>  			break;
> +		}
>  
>  		if (++next_to_process == count)
>  			next_to_process = 0;
> diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
> index 334ae945d640..8975d2971bc3 100644
> --- a/drivers/net/ethernet/intel/ice/ice_xsk.c
> +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
> @@ -801,35 +801,6 @@ ice_run_xdp_zc(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
>  	return result;
>  }
>  
> -static int
> -ice_add_xsk_frag(struct ice_rx_ring *rx_ring, struct xdp_buff *first,
> -		 struct xdp_buff *xdp, const unsigned int size)
> -{
> -	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(first);
> -
> -	if (!size)
> -		return 0;
> -
> -	if (!xdp_buff_has_frags(first)) {
> -		sinfo->nr_frags = 0;
> -		sinfo->xdp_frags_size = 0;
> -		xdp_buff_set_frags_flag(first);
> -	}
> -
> -	if (unlikely(sinfo->nr_frags == MAX_SKB_FRAGS)) {
> -		xsk_buff_free(first);
> -		return -ENOMEM;
> -	}
> -
> -	__skb_fill_page_desc_noacc(sinfo, sinfo->nr_frags++,
> -				   virt_to_page(xdp->data_hard_start),
> -				   XDP_PACKET_HEADROOM, size);
> -	sinfo->xdp_frags_size += size;
> -	xsk_buff_add_frag(xdp);
> -
> -	return 0;
> -}
> -
>  /**
>   * ice_clean_rx_irq_zc - consumes packets from the hardware ring
>   * @rx_ring: AF_XDP Rx ring
> @@ -895,7 +866,8 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring,
>  
>  		if (!first) {
>  			first = xdp;
> -		} else if (ice_add_xsk_frag(rx_ring, first, xdp, size)) {
> +		} else if (likely(size) && !xsk_buff_add_frag(first, xdp)) {
> +			xsk_buff_free(first);
>  			break;
>  		}
>  
> -- 
> 2.46.2
>