Re: [RFC net-next 5/9] ice: apply XDP offloading fixup when building skb

On Fri, Jun 21, 2024 at 4:22 AM Alexander Lobakin
[off-list ref] wrote:

From: Yan Zhai <redacted>
Date: Thu, 20 Jun 2024 15:19:22 -0700

quoted

Add a common point to transfer offloading info from XDP context to skb.

Signed-off-by: Yan Zhai <redacted>
Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
---
 drivers/net/ethernet/intel/ice/ice_txrx.c | 2 ++
 drivers/net/ethernet/intel/ice/ice_xsk.c  | 6 +++++-
 include/net/xdp_sock_drv.h                | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
index 8bb743f78fcb..a247306837ed 100644
--- a/drivers/net/ethernet/intel/ice/ice_txrx.c
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -1222,6 +1222,7 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)

                      hard_start = page_address(rx_buf->page) + rx_buf->page_offset -
                                   offset;
+                     xdp_init_buff_minimal(xdp);

Two lines below, you have this:

        xdp_buff_clear_frags_flag(xdp);

Which clears frags bit in xdp->flags. I.e. since you always clear flags
here, this call becomes redundant.
But I'd say that `xdp->flags = 0` really wants to be moved from
xdp_init_buff() to xdp_prepare_buff().

You are right, there is some redundancy here. I will fix it if people
feel good about the use case in general :)

quoted

                      xdp_prepare_buff(xdp, hard_start, offset, size, !!offset);
 #if (PAGE_SIZE > 4096)
                      /* At larger PAGE_SIZE, frame_sz depend on len size */

@@ -1287,6 +1288,7 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)

              /* populate checksum, VLAN, and protocol */
              ice_process_skb_fields(rx_ring, rx_desc, skb);
+             xdp_buff_fixup_skb_offloading(xdp, skb);

              ice_trace(clean_rx_irq_indicate, rx_ring, rx_desc, skb);
              /* send completed skb up the stack */

diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index a65955eb23c0..367658acaab8 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c

@@ -845,8 +845,10 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
      xdp_prog = READ_ONCE(rx_ring->xdp_prog);
      xdp_ring = rx_ring->xdp_ring;

-     if (ntc != rx_ring->first_desc)
+     if (ntc != rx_ring->first_desc) {
              first = *ice_xdp_buf(rx_ring, rx_ring->first_desc);
+             xdp_init_buff_minimal(first);

xdp_buff_set_size() always clears flags, this is redundant.

quoted

+     }

      while (likely(total_rx_packets < (unsigned int)budget)) {
              union ice_32b_rx_flex_desc *rx_desc;

@@ -920,6 +922,7 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
                      break;
              }

+             xdp = first;
              first = NULL;
              rx_ring->first_desc = ntc;

@@ -934,6 +937,7 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
              vlan_tci = ice_get_vlan_tci(rx_desc);

              ice_process_skb_fields(rx_ring, rx_desc, skb);
+             xdp_buff_fixup_skb_offloading(xdp, skb);
              ice_receive_skb(rx_ring, skb, vlan_tci);
      }

diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index 0a5dca2b2b3f..02243dc064c2 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h

@@ -181,7 +181,7 @@ static inline void xsk_buff_set_size(struct xdp_buff *xdp, u32 size)
      xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM;
      xdp->data_meta = xdp->data;
      xdp->data_end = xdp->data + size;
-     xdp->flags = 0;
+     xdp_init_buff_minimal(xdp);

Why is this done in the patch prefixed with "ice:"?

Good catch, this should be moved to the previous patch.

thanks
Yan

quoted

 }

 static inline dma_addr_t xsk_buff_raw_get_dma(struct xsk_buff_pool *pool,

Thanks,
Olek