net: bnxt: Use dma_unmap_len for TX completion unmapping

Store the DMA mapping length in each TX buffer descriptor via
dma_unmap_len_set at submit time, and use dma_unmap_len at completion
time.

This is a no-op for normal packets but prepares for software USO,
where header BDs set dma_unmap_len to 0 because the header buffer
is unmapped collectively rather than per-segment.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20260408230607.2019402-5-joe@dama.to
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index d1f0969b781c3387f290fdf7051c6e6b9b95cb5e..bc2dac2f137d30923792e4ee1515f3292c8de6f7 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -656,6 +656,7 @@ normal_tx:
                goto tx_free;
 
        dma_unmap_addr_set(tx_buf, mapping, mapping);
+       dma_unmap_len_set(tx_buf, len, len);
        flags = (len << TX_BD_LEN_SHIFT) | TX_BD_TYPE_LONG_TX_BD |
                TX_BD_CNT(last_frag + 2);
 
@@ -720,6 +721,7 @@ normal_tx:
                tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)];
                netmem_dma_unmap_addr_set(skb_frag_netmem(frag), tx_buf,
                                          mapping, mapping);
+               dma_unmap_len_set(tx_buf, len, len);
 
                txbd->tx_bd_haddr = cpu_to_le64(mapping);
 
@@ -809,7 +811,8 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
        u16 hw_cons = txr->tx_hw_cons;
        unsigned int tx_bytes = 0;
        u16 cons = txr->tx_cons;
-       skb_frag_t *frag;
+       unsigned int dma_len;
+       dma_addr_t dma_addr;
        int tx_pkts = 0;
        bool rc = false;
 
@@ -844,19 +847,27 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
                        goto next_tx_int;
                }
 
-               dma_unmap_single(&pdev->dev, dma_unmap_addr(tx_buf, mapping),
-                                skb_headlen(skb), DMA_TO_DEVICE);
+               if (dma_unmap_len(tx_buf, len)) {
+                       dma_addr = dma_unmap_addr(tx_buf, mapping);
+                       dma_len = dma_unmap_len(tx_buf, len);
+
+                       dma_unmap_single(&pdev->dev, dma_addr, dma_len,
+                                        DMA_TO_DEVICE);
+               }
+
                last = tx_buf->nr_frags;
 
                for (j = 0; j < last; j++) {
-                       frag = &skb_shinfo(skb)->frags[j];
                        cons = NEXT_TX(cons);
                        tx_buf = &txr->tx_buf_ring[RING_TX(bp, cons)];
-                       netmem_dma_unmap_page_attrs(&pdev->dev,
-                                                   dma_unmap_addr(tx_buf,
-                                                                  mapping),
-                                                   skb_frag_size(frag),
-                                                   DMA_TO_DEVICE, 0);
+                       if (dma_unmap_len(tx_buf, len)) {
+                               dma_addr = dma_unmap_addr(tx_buf, mapping);
+                               dma_len = dma_unmap_len(tx_buf, len);
+
+                               netmem_dma_unmap_page_attrs(&pdev->dev,
+                                                           dma_addr, dma_len,
+                                                           DMA_TO_DEVICE, 0);
+                       }
                }
                if (unlikely(is_ts_pkt)) {
                        if (BNXT_CHIP_P5(bp)) {
@@ -3394,6 +3405,8 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
 {
        int i, max_idx;
        struct pci_dev *pdev = bp->pdev;
+       unsigned int dma_len;
+       dma_addr_t dma_addr;
 
        max_idx = bp->tx_nr_pages * TX_DESC_CNT;
 
@@ -3404,9 +3417,10 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
 
                if (idx  < bp->tx_nr_rings_xdp &&
                    tx_buf->action == XDP_REDIRECT) {
-                       dma_unmap_single(&pdev->dev,
-                                        dma_unmap_addr(tx_buf, mapping),
-                                        dma_unmap_len(tx_buf, len),
+                       dma_addr = dma_unmap_addr(tx_buf, mapping);
+                       dma_len = dma_unmap_len(tx_buf, len);
+
+                       dma_unmap_single(&pdev->dev, dma_addr, dma_len,
                                         DMA_TO_DEVICE);
                        xdp_return_frame(tx_buf->xdpf);
                        tx_buf->action = 0;
@@ -3429,23 +3443,28 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
                        continue;
                }
 
-               dma_unmap_single(&pdev->dev,
-                                dma_unmap_addr(tx_buf, mapping),
-                                skb_headlen(skb),
-                                DMA_TO_DEVICE);
+               if (dma_unmap_len(tx_buf, len)) {
+                       dma_addr = dma_unmap_addr(tx_buf, mapping);
+                       dma_len = dma_unmap_len(tx_buf, len);
+
+                       dma_unmap_single(&pdev->dev, dma_addr, dma_len,
+                                        DMA_TO_DEVICE);
+               }
 
                last = tx_buf->nr_frags;
                i += 2;
                for (j = 0; j < last; j++, i++) {
                        int ring_idx = i & bp->tx_ring_mask;
-                       skb_frag_t *frag = &skb_shinfo(skb)->frags[j];
 
                        tx_buf = &txr->tx_buf_ring[ring_idx];
-                       netmem_dma_unmap_page_attrs(&pdev->dev,
-                                                   dma_unmap_addr(tx_buf,
-                                                                  mapping),
-                                                   skb_frag_size(frag),
-                                                   DMA_TO_DEVICE, 0);
+                       if (dma_unmap_len(tx_buf, len)) {
+                               dma_addr = dma_unmap_addr(tx_buf, mapping);
+                               dma_len = dma_unmap_len(tx_buf, len);
+
+                               netmem_dma_unmap_page_attrs(&pdev->dev,
+                                                           dma_addr, dma_len,
+                                                           DMA_TO_DEVICE, 0);
+                       }
                }
                dev_kfree_skb(skb);
        }