ixgbe, xsk: Migrate to new MEM_TYPE_XSK_BUFF_POOL
authorBjörn Töpel <bjorn.topel@intel.com>
Wed, 20 May 2020 19:20:58 +0000 (21:20 +0200)
committerAlexei Starovoitov <ast@kernel.org>
Fri, 22 May 2020 00:31:27 +0000 (17:31 -0700)
Remove MEM_TYPE_ZERO_COPY in favor of the new MEM_TYPE_XSK_BUFF_POOL
APIs.

v1->v2: Fixed xdp_buff data_end update. (Björn)

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Link: https://lore.kernel.org/bpf/20200520192103.355233-11-bjorn.topel@gmail.com
drivers/net/ethernet/intel/ixgbe/ixgbe.h
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c

index 2833e4f..5ddfc83 100644 (file)
@@ -224,17 +224,17 @@ struct ixgbe_tx_buffer {
 };
 
 struct ixgbe_rx_buffer {
-       struct sk_buff *skb;
-       dma_addr_t dma;
        union {
                struct {
+                       struct sk_buff *skb;
+                       dma_addr_t dma;
                        struct page *page;
                        __u32 page_offset;
                        __u16 pagecnt_bias;
                };
                struct {
-                       void *addr;
-                       u64 handle;
+                       bool discard;
+                       struct xdp_buff *xdp;
                };
        };
 };
@@ -351,7 +351,6 @@ struct ixgbe_ring {
        };
        struct xdp_rxq_info xdp_rxq;
        struct xdp_umem *xsk_umem;
-       struct zero_copy_allocator zca; /* ZC allocator anchor */
        u16 ring_idx;           /* {rx,tx,xdp}_ring back reference idx */
        u16 rx_buf_len;
 } ____cacheline_internodealigned_in_smp;
index eab5934..45fc7ce 100644 (file)
@@ -35,7 +35,7 @@
 #include <net/tc_act/tc_mirred.h>
 #include <net/vxlan.h>
 #include <net/mpls.h>
-#include <net/xdp_sock.h>
+#include <net/xdp_sock_drv.h>
 #include <net/xfrm.h>
 
 #include "ixgbe.h"
@@ -3745,8 +3745,7 @@ static void ixgbe_configure_srrctl(struct ixgbe_adapter *adapter,
 
        /* configure the packet buffer length */
        if (rx_ring->xsk_umem) {
-               u32 xsk_buf_len = rx_ring->xsk_umem->chunk_size_nohr -
-                                 XDP_PACKET_HEADROOM;
+               u32 xsk_buf_len = xsk_umem_get_rx_frame_size(rx_ring->xsk_umem);
 
                /* If the MAC support setting RXDCTL.RLPML, the
                 * SRRCTL[n].BSIZEPKT is set to PAGE_SIZE and
@@ -4093,11 +4092,10 @@ void ixgbe_configure_rx_ring(struct ixgbe_adapter *adapter,
        xdp_rxq_info_unreg_mem_model(&ring->xdp_rxq);
        ring->xsk_umem = ixgbe_xsk_umem(adapter, ring);
        if (ring->xsk_umem) {
-               ring->zca.free = ixgbe_zca_free;
                WARN_ON(xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
-                                                  MEM_TYPE_ZERO_COPY,
-                                                  &ring->zca));
-
+                                                  MEM_TYPE_XSK_BUFF_POOL,
+                                                  NULL));
+               xsk_buff_set_rxq_info(ring->xsk_umem, &ring->xdp_rxq);
        } else {
                WARN_ON(xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
                                                   MEM_TYPE_PAGE_SHARED, NULL));
@@ -4153,8 +4151,7 @@ void ixgbe_configure_rx_ring(struct ixgbe_adapter *adapter,
        }
 
        if (ring->xsk_umem && hw->mac.type != ixgbe_mac_82599EB) {
-               u32 xsk_buf_len = ring->xsk_umem->chunk_size_nohr -
-                                 XDP_PACKET_HEADROOM;
+               u32 xsk_buf_len = xsk_umem_get_rx_frame_size(ring->xsk_umem);
 
                rxdctl &= ~(IXGBE_RXDCTL_RLPMLMASK |
                            IXGBE_RXDCTL_RLPML_EN);
index 6d01700..7887ae4 100644 (file)
@@ -35,7 +35,7 @@ int ixgbe_xsk_umem_setup(struct ixgbe_adapter *adapter, struct xdp_umem *umem,
 
 void ixgbe_zca_free(struct zero_copy_allocator *alloc, unsigned long handle);
 
-void ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count);
+bool ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count);
 int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
                          struct ixgbe_ring *rx_ring,
                          const int budget);
index 82e4eff..86add9f 100644 (file)
@@ -20,54 +20,11 @@ struct xdp_umem *ixgbe_xsk_umem(struct ixgbe_adapter *adapter,
        return xdp_get_umem_from_qid(adapter->netdev, qid);
 }
 
-static int ixgbe_xsk_umem_dma_map(struct ixgbe_adapter *adapter,
-                                 struct xdp_umem *umem)
-{
-       struct device *dev = &adapter->pdev->dev;
-       unsigned int i, j;
-       dma_addr_t dma;
-
-       for (i = 0; i < umem->npgs; i++) {
-               dma = dma_map_page_attrs(dev, umem->pgs[i], 0, PAGE_SIZE,
-                                        DMA_BIDIRECTIONAL, IXGBE_RX_DMA_ATTR);
-               if (dma_mapping_error(dev, dma))
-                       goto out_unmap;
-
-               umem->pages[i].dma = dma;
-       }
-
-       return 0;
-
-out_unmap:
-       for (j = 0; j < i; j++) {
-               dma_unmap_page_attrs(dev, umem->pages[i].dma, PAGE_SIZE,
-                                    DMA_BIDIRECTIONAL, IXGBE_RX_DMA_ATTR);
-               umem->pages[i].dma = 0;
-       }
-
-       return -1;
-}
-
-static void ixgbe_xsk_umem_dma_unmap(struct ixgbe_adapter *adapter,
-                                    struct xdp_umem *umem)
-{
-       struct device *dev = &adapter->pdev->dev;
-       unsigned int i;
-
-       for (i = 0; i < umem->npgs; i++) {
-               dma_unmap_page_attrs(dev, umem->pages[i].dma, PAGE_SIZE,
-                                    DMA_BIDIRECTIONAL, IXGBE_RX_DMA_ATTR);
-
-               umem->pages[i].dma = 0;
-       }
-}
-
 static int ixgbe_xsk_umem_enable(struct ixgbe_adapter *adapter,
                                 struct xdp_umem *umem,
                                 u16 qid)
 {
        struct net_device *netdev = adapter->netdev;
-       struct xdp_umem_fq_reuse *reuseq;
        bool if_running;
        int err;
 
@@ -78,13 +35,7 @@ static int ixgbe_xsk_umem_enable(struct ixgbe_adapter *adapter,
            qid >= netdev->real_num_tx_queues)
                return -EINVAL;
 
-       reuseq = xsk_reuseq_prepare(adapter->rx_ring[0]->count);
-       if (!reuseq)
-               return -ENOMEM;
-
-       xsk_reuseq_free(xsk_reuseq_swap(umem, reuseq));
-
-       err = ixgbe_xsk_umem_dma_map(adapter, umem);
+       err = xsk_buff_dma_map(umem, &adapter->pdev->dev, IXGBE_RX_DMA_ATTR);
        if (err)
                return err;
 
@@ -124,7 +75,7 @@ static int ixgbe_xsk_umem_disable(struct ixgbe_adapter *adapter, u16 qid)
                ixgbe_txrx_ring_disable(adapter, qid);
 
        clear_bit(qid, adapter->af_xdp_zc_qps);
-       ixgbe_xsk_umem_dma_unmap(adapter, umem);
+       xsk_buff_dma_unmap(umem, IXGBE_RX_DMA_ATTR);
 
        if (if_running)
                ixgbe_txrx_ring_enable(adapter, qid);
@@ -143,19 +94,14 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
                            struct ixgbe_ring *rx_ring,
                            struct xdp_buff *xdp)
 {
-       struct xdp_umem *umem = rx_ring->xsk_umem;
        int err, result = IXGBE_XDP_PASS;
        struct bpf_prog *xdp_prog;
        struct xdp_frame *xdpf;
-       u64 offset;
        u32 act;
 
        rcu_read_lock();
        xdp_prog = READ_ONCE(rx_ring->xdp_prog);
        act = bpf_prog_run_xdp(xdp_prog, xdp);
-       offset = xdp->data - xdp->data_hard_start;
-
-       xdp->handle = xsk_umem_adjust_offset(umem, xdp->handle, offset);
 
        switch (act) {
        case XDP_PASS:
@@ -186,140 +132,16 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
        return result;
 }
 
-static struct
-ixgbe_rx_buffer *ixgbe_get_rx_buffer_zc(struct ixgbe_ring *rx_ring,
-                                       unsigned int size)
-{
-       struct ixgbe_rx_buffer *bi;
-
-       bi = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
-
-       /* we are reusing so sync this buffer for CPU use */
-       dma_sync_single_range_for_cpu(rx_ring->dev,
-                                     bi->dma, 0,
-                                     size,
-                                     DMA_BIDIRECTIONAL);
-
-       return bi;
-}
-
-static void ixgbe_reuse_rx_buffer_zc(struct ixgbe_ring *rx_ring,
-                                    struct ixgbe_rx_buffer *obi)
-{
-       u16 nta = rx_ring->next_to_alloc;
-       struct ixgbe_rx_buffer *nbi;
-
-       nbi = &rx_ring->rx_buffer_info[rx_ring->next_to_alloc];
-       /* update, and store next to alloc */
-       nta++;
-       rx_ring->next_to_alloc = (nta < rx_ring->count) ? nta : 0;
-
-       /* transfer page from old buffer to new buffer */
-       nbi->dma = obi->dma;
-       nbi->addr = obi->addr;
-       nbi->handle = obi->handle;
-
-       obi->addr = NULL;
-       obi->skb = NULL;
-}
-
-void ixgbe_zca_free(struct zero_copy_allocator *alloc, unsigned long handle)
-{
-       struct ixgbe_rx_buffer *bi;
-       struct ixgbe_ring *rx_ring;
-       u64 hr, mask;
-       u16 nta;
-
-       rx_ring = container_of(alloc, struct ixgbe_ring, zca);
-       hr = rx_ring->xsk_umem->headroom + XDP_PACKET_HEADROOM;
-       mask = rx_ring->xsk_umem->chunk_mask;
-
-       nta = rx_ring->next_to_alloc;
-       bi = rx_ring->rx_buffer_info;
-
-       nta++;
-       rx_ring->next_to_alloc = (nta < rx_ring->count) ? nta : 0;
-
-       handle &= mask;
-
-       bi->dma = xdp_umem_get_dma(rx_ring->xsk_umem, handle);
-       bi->dma += hr;
-
-       bi->addr = xdp_umem_get_data(rx_ring->xsk_umem, handle);
-       bi->addr += hr;
-
-       bi->handle = xsk_umem_adjust_offset(rx_ring->xsk_umem, (u64)handle,
-                                           rx_ring->xsk_umem->headroom);
-}
-
-static bool ixgbe_alloc_buffer_zc(struct ixgbe_ring *rx_ring,
-                                 struct ixgbe_rx_buffer *bi)
-{
-       struct xdp_umem *umem = rx_ring->xsk_umem;
-       void *addr = bi->addr;
-       u64 handle, hr;
-
-       if (addr)
-               return true;
-
-       if (!xsk_umem_peek_addr(umem, &handle)) {
-               rx_ring->rx_stats.alloc_rx_page_failed++;
-               return false;
-       }
-
-       hr = umem->headroom + XDP_PACKET_HEADROOM;
-
-       bi->dma = xdp_umem_get_dma(umem, handle);
-       bi->dma += hr;
-
-       bi->addr = xdp_umem_get_data(umem, handle);
-       bi->addr += hr;
-
-       bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
-
-       xsk_umem_release_addr(umem);
-       return true;
-}
-
-static bool ixgbe_alloc_buffer_slow_zc(struct ixgbe_ring *rx_ring,
-                                      struct ixgbe_rx_buffer *bi)
-{
-       struct xdp_umem *umem = rx_ring->xsk_umem;
-       u64 handle, hr;
-
-       if (!xsk_umem_peek_addr_rq(umem, &handle)) {
-               rx_ring->rx_stats.alloc_rx_page_failed++;
-               return false;
-       }
-
-       handle &= rx_ring->xsk_umem->chunk_mask;
-
-       hr = umem->headroom + XDP_PACKET_HEADROOM;
-
-       bi->dma = xdp_umem_get_dma(umem, handle);
-       bi->dma += hr;
-
-       bi->addr = xdp_umem_get_data(umem, handle);
-       bi->addr += hr;
-
-       bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
-
-       xsk_umem_release_addr_rq(umem);
-       return true;
-}
-
-static __always_inline bool
-__ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count,
-                           bool alloc(struct ixgbe_ring *rx_ring,
-                                      struct ixgbe_rx_buffer *bi))
+bool ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 count)
 {
        union ixgbe_adv_rx_desc *rx_desc;
        struct ixgbe_rx_buffer *bi;
        u16 i = rx_ring->next_to_use;
+       dma_addr_t dma;
        bool ok = true;
 
        /* nothing to do */
-       if (!cleaned_count)
+       if (!count)
                return true;
 
        rx_desc = IXGBE_RX_DESC(rx_ring, i);
@@ -327,21 +149,18 @@ __ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count,
        i -= rx_ring->count;
 
        do {
-               if (!alloc(rx_ring, bi)) {
+               bi->xdp = xsk_buff_alloc(rx_ring->xsk_umem);
+               if (!bi->xdp) {
                        ok = false;
                        break;
                }
 
-               /* sync the buffer for use by the device */
-               dma_sync_single_range_for_device(rx_ring->dev, bi->dma,
-                                                bi->page_offset,
-                                                rx_ring->rx_buf_len,
-                                                DMA_BIDIRECTIONAL);
+               dma = xsk_buff_xdp_get_dma(bi->xdp);
 
                /* Refresh the desc even if buffer_addrs didn't change
                 * because each write-back erases this info.
                 */
-               rx_desc->read.pkt_addr = cpu_to_le64(bi->dma);
+               rx_desc->read.pkt_addr = cpu_to_le64(dma);
 
                rx_desc++;
                bi++;
@@ -355,17 +174,14 @@ __ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count,
                /* clear the length for the next_to_use descriptor */
                rx_desc->wb.upper.length = 0;
 
-               cleaned_count--;
-       } while (cleaned_count);
+               count--;
+       } while (count);
 
        i += rx_ring->count;
 
        if (rx_ring->next_to_use != i) {
                rx_ring->next_to_use = i;
 
-               /* update next to alloc since we have filled the ring */
-               rx_ring->next_to_alloc = i;
-
                /* Force memory writes to complete before letting h/w
                 * know there are new descriptors to fetch.  (Only
                 * applicable for weak-ordered memory model archs,
@@ -378,40 +194,27 @@ __ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 cleaned_count,
        return ok;
 }
 
-void ixgbe_alloc_rx_buffers_zc(struct ixgbe_ring *rx_ring, u16 count)
-{
-       __ixgbe_alloc_rx_buffers_zc(rx_ring, count,
-                                   ixgbe_alloc_buffer_slow_zc);
-}
-
-static bool ixgbe_alloc_rx_buffers_fast_zc(struct ixgbe_ring *rx_ring,
-                                          u16 count)
-{
-       return __ixgbe_alloc_rx_buffers_zc(rx_ring, count,
-                                          ixgbe_alloc_buffer_zc);
-}
-
 static struct sk_buff *ixgbe_construct_skb_zc(struct ixgbe_ring *rx_ring,
-                                             struct ixgbe_rx_buffer *bi,
-                                             struct xdp_buff *xdp)
+                                             struct ixgbe_rx_buffer *bi)
 {
-       unsigned int metasize = xdp->data - xdp->data_meta;
-       unsigned int datasize = xdp->data_end - xdp->data;
+       unsigned int metasize = bi->xdp->data - bi->xdp->data_meta;
+       unsigned int datasize = bi->xdp->data_end - bi->xdp->data;
        struct sk_buff *skb;
 
        /* allocate a skb to store the frags */
        skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
-                              xdp->data_end - xdp->data_hard_start,
+                              bi->xdp->data_end - bi->xdp->data_hard_start,
                               GFP_ATOMIC | __GFP_NOWARN);
        if (unlikely(!skb))
                return NULL;
 
-       skb_reserve(skb, xdp->data - xdp->data_hard_start);
-       memcpy(__skb_put(skb, datasize), xdp->data, datasize);
+       skb_reserve(skb, bi->xdp->data - bi->xdp->data_hard_start);
+       memcpy(__skb_put(skb, datasize), bi->xdp->data, datasize);
        if (metasize)
                skb_metadata_set(skb, metasize);
 
-       ixgbe_reuse_rx_buffer_zc(rx_ring, bi);
+       xsk_buff_free(bi->xdp);
+       bi->xdp = NULL;
        return skb;
 }
 
@@ -431,14 +234,9 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
        unsigned int total_rx_bytes = 0, total_rx_packets = 0;
        struct ixgbe_adapter *adapter = q_vector->adapter;
        u16 cleaned_count = ixgbe_desc_unused(rx_ring);
-       struct xdp_umem *umem = rx_ring->xsk_umem;
        unsigned int xdp_res, xdp_xmit = 0;
        bool failure = false;
        struct sk_buff *skb;
-       struct xdp_buff xdp;
-
-       xdp.rxq = &rx_ring->xdp_rxq;
-       xdp.frame_sz = xsk_umem_xdp_frame_sz(umem);
 
        while (likely(total_rx_packets < budget)) {
                union ixgbe_adv_rx_desc *rx_desc;
@@ -448,8 +246,8 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
                /* return some buffers to hardware, one at a time is too slow */
                if (cleaned_count >= IXGBE_RX_BUFFER_WRITE) {
                        failure = failure ||
-                                 !ixgbe_alloc_rx_buffers_fast_zc(rx_ring,
-                                                                cleaned_count);
+                                 !ixgbe_alloc_rx_buffers_zc(rx_ring,
+                                                            cleaned_count);
                        cleaned_count = 0;
                }
 
@@ -464,42 +262,40 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
                 */
                dma_rmb();
 
-               bi = ixgbe_get_rx_buffer_zc(rx_ring, size);
+               bi = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
 
                if (unlikely(!ixgbe_test_staterr(rx_desc,
                                                 IXGBE_RXD_STAT_EOP))) {
                        struct ixgbe_rx_buffer *next_bi;
 
-                       ixgbe_reuse_rx_buffer_zc(rx_ring, bi);
+                       xsk_buff_free(bi->xdp);
+                       bi->xdp = NULL;
                        ixgbe_inc_ntc(rx_ring);
                        next_bi =
                               &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
-                       next_bi->skb = ERR_PTR(-EINVAL);
+                       next_bi->discard = true;
                        continue;
                }
 
-               if (unlikely(bi->skb)) {
-                       ixgbe_reuse_rx_buffer_zc(rx_ring, bi);
+               if (unlikely(bi->discard)) {
+                       xsk_buff_free(bi->xdp);
+                       bi->xdp = NULL;
+                       bi->discard = false;
                        ixgbe_inc_ntc(rx_ring);
                        continue;
                }
 
-               xdp.data = bi->addr;
-               xdp.data_meta = xdp.data;
-               xdp.data_hard_start = xdp.data - XDP_PACKET_HEADROOM;
-               xdp.data_end = xdp.data + size;
-               xdp.handle = bi->handle;
-
-               xdp_res = ixgbe_run_xdp_zc(adapter, rx_ring, &xdp);
+               bi->xdp->data_end = bi->xdp->data + size;
+               xsk_buff_dma_sync_for_cpu(bi->xdp);
+               xdp_res = ixgbe_run_xdp_zc(adapter, rx_ring, bi->xdp);
 
                if (xdp_res) {
-                       if (xdp_res & (IXGBE_XDP_TX | IXGBE_XDP_REDIR)) {
+                       if (xdp_res & (IXGBE_XDP_TX | IXGBE_XDP_REDIR))
                                xdp_xmit |= xdp_res;
-                               bi->addr = NULL;
-                               bi->skb = NULL;
-                       } else {
-                               ixgbe_reuse_rx_buffer_zc(rx_ring, bi);
-                       }
+                       else
+                               xsk_buff_free(bi->xdp);
+
+                       bi->xdp = NULL;
                        total_rx_packets++;
                        total_rx_bytes += size;
 
@@ -509,7 +305,7 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
                }
 
                /* XDP_PASS path */
-               skb = ixgbe_construct_skb_zc(rx_ring, bi, &xdp);
+               skb = ixgbe_construct_skb_zc(rx_ring, bi);
                if (!skb) {
                        rx_ring->rx_stats.alloc_rx_buff_failed++;
                        break;
@@ -561,17 +357,17 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
 
 void ixgbe_xsk_clean_rx_ring(struct ixgbe_ring *rx_ring)
 {
-       u16 i = rx_ring->next_to_clean;
-       struct ixgbe_rx_buffer *bi = &rx_ring->rx_buffer_info[i];
+       struct ixgbe_rx_buffer *bi;
+       u16 i;
 
-       while (i != rx_ring->next_to_alloc) {
-               xsk_umem_fq_reuse(rx_ring->xsk_umem, bi->handle);
-               i++;
-               bi++;
-               if (i == rx_ring->count) {
-                       i = 0;
-                       bi = rx_ring->rx_buffer_info;
-               }
+       for (i = 0; i < rx_ring->count; i++) {
+               bi = &rx_ring->rx_buffer_info[i];
+
+               if (!bi->xdp)
+                       continue;
+
+               xsk_buff_free(bi->xdp);
+               bi->xdp = NULL;
        }
 }
 
@@ -594,10 +390,9 @@ static bool ixgbe_xmit_zc(struct ixgbe_ring *xdp_ring, unsigned int budget)
                if (!xsk_umem_consume_tx(xdp_ring->xsk_umem, &desc))
                        break;
 
-               dma = xdp_umem_get_dma(xdp_ring->xsk_umem, desc.addr);
-
-               dma_sync_single_for_device(xdp_ring->dev, dma, desc.len,
-                                          DMA_BIDIRECTIONAL);
+               dma = xsk_buff_raw_get_dma(xdp_ring->xsk_umem, desc.addr);
+               xsk_buff_raw_dma_sync_for_device(xdp_ring->xsk_umem, dma,
+                                                desc.len);
 
                tx_bi = &xdp_ring->tx_buffer_info[xdp_ring->next_to_use];
                tx_bi->bytecount = desc.len;