net: airoha: dma map xmit frags with skb_frag_dma_map()

Map xmit skb fragments using skb_frag_dma_map() instead of
dma_map_single(skb_frag_address()). skb_frag_address() relies on
page_address() to obtain a kernel virtual address, which is not
guaranteed to work for all page types (e.g. highmem pages or
user-pinned pages from MSG_ZEROCOPY).
skb_frag_dma_map() maps the fragment directly via its struct page and
offset through dma_map_page(), avoiding the need for a kernel virtual
address entirely.
Introduce an enum airoha_dma_map_type to track how each queue entry was
mapped (single vs page), so that the matching unmap function is called
on completion and in error paths.

Fixes: 23020f049327 ("net: airoha: Introduce ethernet support for EN7581 SoC")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Link: https://patch.msgid.link/20260625-airoha-eth-skb_frag_dma_map-v1-1-31d9e460aae6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 932b3a3df2e577b15e901b8c29507afe48bdfe4f..1caf6766f2c02e11bb7f62bd245f2f4277f51b7d 100644 (file)
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -944,6 +944,25 @@ static void airoha_qdma_wake_netdev_txqs(struct airoha_queue *q)
        q->txq_stopped = false;
 }
 
+static void airoha_unmap_xmit_buf(struct airoha_eth *eth,
+                                 struct airoha_queue_entry *e)
+{
+       switch (e->dma_type) {
+       case AIROHA_DMA_MAP_PAGE:
+               dma_unmap_page(eth->dev, e->dma_addr, e->dma_len,
+                              DMA_TO_DEVICE);
+               break;
+       case AIROHA_DMA_MAP_SINGLE:
+               dma_unmap_single(eth->dev, e->dma_addr, e->dma_len,
+                                DMA_TO_DEVICE);
+               break;
+       case AIROHA_DMA_UNMAPPED:
+       default:
+               break;
+       }
+       e->dma_type = AIROHA_DMA_UNMAPPED;
+}
+
 static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
 {
        struct airoha_tx_irq_queue *irq_q;
@@ -1006,9 +1025,7 @@ static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
                skb = e->skb;
                e->skb = NULL;
 
-               dma_unmap_single(eth->dev, e->dma_addr, e->dma_len,
-                                DMA_TO_DEVICE);
-               e->dma_addr = 0;
+               airoha_unmap_xmit_buf(eth, e);
                list_add_tail(&e->list, &q->tx_list);
 
                WRITE_ONCE(desc->msg0, 0);
@@ -1177,12 +1194,10 @@ static void airoha_qdma_tx_cleanup(struct airoha_qdma *qdma)
                        struct airoha_qdma_desc *desc = &q->desc[j];
                        struct sk_buff *skb = e->skb;
 
-                       if (!e->dma_addr)
+                       if (e->dma_type == AIROHA_DMA_UNMAPPED)
                                continue;
 
-                       dma_unmap_single(qdma->eth->dev, e->dma_addr,
-                                        e->dma_len, DMA_TO_DEVICE);
-                       e->dma_addr = 0;
+                       airoha_unmap_xmit_buf(qdma->eth, e);
                        list_add_tail(&e->list, &q->tx_list);
 
                        WRITE_ONCE(desc->ctrl, 0);
@@ -2193,8 +2208,8 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
        struct netdev_queue *txq;
        struct airoha_queue *q;
        LIST_HEAD(tx_list);
+       dma_addr_t addr;
        int i = 0, qid;
-       void *data;
        u16 index;
        u8 fport;
 
@@ -2250,24 +2265,22 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
                return NETDEV_TX_BUSY;
        }
 
-       len = skb_headlen(skb);
-       data = skb->data;
-
        e = list_first_entry(&q->tx_list, struct airoha_queue_entry,
                             list);
+       len = skb_headlen(skb);
+       addr = dma_map_single(netdev->dev.parent, skb->data, len,
+                             DMA_TO_DEVICE);
+       if (unlikely(dma_mapping_error(netdev->dev.parent, addr)))
+               goto error_unlock;
+
+       e->dma_type = AIROHA_DMA_MAP_SINGLE;
        index = e - q->entry;
 
        while (true) {
                struct airoha_qdma_desc *desc = &q->desc[index];
                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
-               dma_addr_t addr;
                u32 val;
 
-               addr = dma_map_single(netdev->dev.parent, data, len,
-                                     DMA_TO_DEVICE);
-               if (unlikely(dma_mapping_error(netdev->dev.parent, addr)))
-                       goto error_unmap;
-
                list_move_tail(&e->list, &tx_list);
                e->skb = i == nr_frags - 1 ? skb : NULL;
                e->dma_addr = addr;
@@ -2291,8 +2304,13 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
                if (++i == nr_frags)
                        break;
 
-               data = skb_frag_address(frag);
                len = skb_frag_size(frag);
+               addr = skb_frag_dma_map(netdev->dev.parent, frag, 0, len,
+                                       DMA_TO_DEVICE);
+               if (unlikely(dma_mapping_error(netdev->dev.parent, addr)))
+                       goto error_unmap;
+
+               e->dma_type = AIROHA_DMA_MAP_PAGE;
        }
        q->queued += i;
 
@@ -2313,11 +2331,8 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
        return NETDEV_TX_OK;
 
 error_unmap:
-       list_for_each_entry(e, &tx_list, list) {
-               dma_unmap_single(netdev->dev.parent, e->dma_addr, e->dma_len,
-                                DMA_TO_DEVICE);
-               e->dma_addr = 0;
-       }
+       list_for_each_entry(e, &tx_list, list)
+               airoha_unmap_xmit_buf(dev->eth, e);
        list_splice(&tx_list, &q->tx_list);
 error_unlock:
        spin_unlock_bh(&q->lock);

diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
index d7ff8c5200e20cca1c54032e19d7b47b07054cb0..2765244d937cfb2e5052138b418b2d112a786be2 100644 (file)
--- a/drivers/net/ethernet/airoha/airoha_eth.h
+++ b/drivers/net/ethernet/airoha/airoha_eth.h
@@ -170,12 +170,19 @@ enum trtcm_param {
 #define TRTCM_TOKEN_RATE_MASK                  GENMASK(23, 6)
 #define TRTCM_TOKEN_RATE_FRACTION_MASK         GENMASK(5, 0)
 
+enum airoha_dma_map_type {
+       AIROHA_DMA_UNMAPPED,
+       AIROHA_DMA_MAP_SINGLE,
+       AIROHA_DMA_MAP_PAGE,
+};
+
 struct airoha_queue_entry {
        union {
                void *buf;
                struct {
                        struct list_head list;
                        struct sk_buff *skb;
+                       enum airoha_dma_map_type dma_type;
                };
        };
        dma_addr_t dma_addr;