net: convert netmem_tx flag to enum

Devices that support netmem TX previously set dev->netmem_tx = true.
This was checked in validate_xmit_unreadable_skb() to drop unreadable
skbs (skbs with dmabuf-backed frags) before they reach drivers that
would mishandle them or devices that would not have the iommu mappings
for them.

A subsequent patch will introduce a third state for virtual devices
that forward unreadable skbs without ever performing DMA on them. To
prepare for that, convert the boolean dev->netmem_tx into an enum:

NETMEM_TX_NONE   - no netmem TX support (drop unreadable skbs)
NETMEM_TX_DMA    - full support, device does DMA

Update the existing NIC drivers (bnxt, gve, mlx5, fbnic) and the
validators in net/core to use the new enum. No functional change.

Acked-by: Harshitha Ramamurthy <hramamurthy@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260514-tcp-dm-netkit-v5-1-408c59b91e66@meta.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/netmem.rst b/Documentation/networking/netmem.rst
index b63aded4633707116d2c3402f5cd4eba07b67f02..5ccadba4f373ee1d733795b577fe38afba3cb87e 100644 (file)
--- a/Documentation/networking/netmem.rst
+++ b/Documentation/networking/netmem.rst
@@ -95,4 +95,7 @@ Driver TX Requirements
    netdev@, or reach out to the maintainers and/or almasrymina@google.com for
    help adding the netmem API.
 
-2. Driver should declare support by setting `netdev->netmem_tx = true`
+2. Driver should declare support by setting `netdev->netmem_tx` to the
+   appropriate mode:
+
+   - `NETMEM_TX_DMA`: for physical devices that perform DMA.

diff --git a/Documentation/translations/zh_CN/networking/netmem.rst b/Documentation/translations/zh_CN/networking/netmem.rst
index fe351a240f021121aa4f6072567279d4d1a1d061..9c84423b752809e4e7eb6b4b906b1dca7eea89cf 100644 (file)
--- a/Documentation/translations/zh_CN/networking/netmem.rst
+++ b/Documentation/translations/zh_CN/networking/netmem.rst
@@ -89,4 +89,6 @@ dma-mapping API 去处理。
 使用某个还不存在的 netmem API，你可以自行添加并提交到 netdev@，也可以联系维护
 人员或者发送邮件至 almasrymina@google.com 寻求帮助。
 
-2. 驱动程序应通过设置 netdev->netmem_tx = true 来表明自身支持 netmem 功能。
+2. 驱动程序应将 `netdev->netmem_tx` 设置为适当的模式：
+
+   - `NETMEM_TX_DMA`：适用于执行 DMA 的物理设备。

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 945a86696f2f0e7de52532c201dd1acf8b182d74..d4f93e62f583640383a8becace33ef64eb8223e7 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -17123,7 +17123,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        dev->queue_mgmt_ops = &bnxt_queue_mgmt_ops_unsupp;
        if (BNXT_SUPPORTS_QUEUE_API(bp))
                dev->queue_mgmt_ops = &bnxt_queue_mgmt_ops;
-       dev->netmem_tx = true;
+       dev->netmem_tx = NETMEM_TX_DMA;
 
        rc = register_netdev(dev);
        if (rc)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 00750643e614f0a14fb8d36ce7ba73d6d039caac..e4d78ae52dafece67b3e04f9d136f18858e49cd7 100644 (file)
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -2894,7 +2894,7 @@ static int gve_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
                goto abort_with_wq;
 
        if (!gve_is_gqi(priv) && !gve_is_qpl(priv))
-               dev->netmem_tx = true;
+               dev->netmem_tx = NETMEM_TX_DMA;
 
        err = register_netdev(dev);
        if (err)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index a904e468c1977acdb56a2f2437ad85c06b070647..c5d26c6829a0d171d14bed7efa677b09f05df457 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -5963,7 +5963,7 @@ static void mlx5e_build_nic_netdev(struct net_device *netdev)
 
        netdev->priv_flags       |= IFF_UNICAST_FLT;
 
-       netdev->netmem_tx = true;
+       netdev->netmem_tx = NETMEM_TX_DMA;
 
        netif_set_tso_max_size(netdev, GSO_MAX_SIZE);
        mlx5e_set_xdp_feature(priv);

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
index 4dea2bb58d2fcae73d50562c8f6ad81fbe152130..f99ca551c1ceb31cb13b840da072e8296b2ca52b 100644 (file)
--- a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
@@ -752,7 +752,7 @@ struct net_device *fbnic_netdev_alloc(struct fbnic_dev *fbd)
        netdev->netdev_ops = &fbnic_netdev_ops;
        netdev->stat_ops = &fbnic_stat_ops;
        netdev->queue_mgmt_ops = &fbnic_queue_mgmt_ops;
-       netdev->netmem_tx = true;
+       netdev->netmem_tx = NETMEM_TX_DMA;
 
        fbnic_set_ethtool_ops(netdev);
 

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e7af71491a475928b13bd17a97b1427a3a2f8dd1..b7a4503f7cdb65ff831c0cea1ae0a07bee2c16e7 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1794,6 +1794,11 @@ enum netdev_stat_type {
        NETDEV_PCPU_STAT_DSTATS, /* struct pcpu_dstats */
 };
 
+enum netmem_tx_mode {
+       NETMEM_TX_NONE,         /* no netmem TX support */
+       NETMEM_TX_DMA,          /* DMA-capable netmem TX (real HW) */
+};
+
 enum netdev_reg_state {
        NETREG_UNINITIALIZED = 0,
        NETREG_REGISTERED,      /* completed register_netdevice */
@@ -1815,7 +1820,7 @@ enum netdev_reg_state {
  *     @lltx:          device supports lockless Tx. Deprecated for real HW
  *                     drivers. Mainly used by logical interfaces, such as
  *                     bonding and tunnels
- *     @netmem_tx:     device support netmem_tx.
+ *     @netmem_tx:     device netmem TX mode
  *
  *     @name:  This is the first field of the "visible" part of this structure
  *             (i.e. as seen by users in the "Space.c" file).  It is the name

diff --git a/net/core/dev.c b/net/core/dev.c
index 267cf3854395fb2eab4fe74269942388f4ea8056..23c1ad3d393da03955741b514c71267b83867a07 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3996,7 +3996,7 @@ static struct sk_buff *validate_xmit_unreadable_skb(struct sk_buff *skb,
        if (likely(skb_frags_readable(skb)))
                goto out;
 
-       if (!dev->netmem_tx)
+       if (dev->netmem_tx == NETMEM_TX_NONE)
                goto out_free;
 
        shinfo = skb_shinfo(skb);

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index b8f6076d80072fd1114ef4d4000647c18416a8bb..4d2c49371cdb4b7768afce05412e60f62069ef76 100644 (file)
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -1164,7 +1164,7 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
                goto err_unlock_netdev;
        }
 
-       if (!netdev->netmem_tx) {
+       if (netdev->netmem_tx == NETMEM_TX_NONE) {
                err = -EOPNOTSUPP;
                NL_SET_ERR_MSG(info->extack,
                               "Driver does not support netmem TX");