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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , Alex Shi , Yanteng Si , Dongliang Mu , Michael Chan , Pavan Chebbi , Joshua Washington , Harshitha Ramamurthy , Saeed Mahameed , Tariq Toukan , Mark Bloch , Leon Romanovsky , Alexander Duyck , kernel-team@meta.com, Daniel Borkmann , Nikolay Aleksandrov , Shuah Khan , dw@davidwei.uk, mohsin.bashr@gmail.com, willemb@google.com, jiang.kun2@zte.com.cn, xu.xin16@zte.com.cn, wang.yaxin@zte.com.cn, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, Stanislav Fomichev , Mina Almasry , Bobby Eshleman Subject: Re: [PATCH net-next v3 1/8] net: convert netmem_tx flag to enum Message-ID: References: <20260507-tcp-dm-netkit-v3-0-52821445867c@meta.com> <20260507-tcp-dm-netkit-v3-1-52821445867c@meta.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, May 08, 2026 at 07:56:42AM -0700, Stanislav Fomichev wrote: > On 05/07, Bobby Eshleman wrote: > > From: Bobby Eshleman > > > > 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 > > Signed-off-by: Bobby Eshleman > > --- > > Changes in v3: > > - Split NO_DMA changes into subsequent commit (Jakub) > > - Move !netdev->netmem_tx -> netdev->netmem_tx == > > NETMEM_TX_NONE conversions to this patch (Jakub) > > > > Changes in v2: > > - Squash driver conversion patches (2-5) into patch 1 (Jakub) > > --- > > Documentation/networking/netmem.rst | 5 ++++- > > Documentation/translations/zh_CN/networking/netmem.rst | 4 +++- > > drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 +- > > drivers/net/ethernet/google/gve/gve_main.c | 2 +- > > drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 2 +- > > drivers/net/ethernet/meta/fbnic/fbnic_netdev.c | 2 +- > > include/linux/netdevice.h | 8 +++++++- > > net/core/dev.c | 2 +- > > net/core/netdev-genl.c | 2 +- > > 9 files changed, 20 insertions(+), 9 deletions(-) > > > > diff --git a/Documentation/networking/netmem.rst b/Documentation/networking/netmem.rst > > index b63aded46337..5ccadba4f373 100644 > > --- 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 fe351a240f02..9c84423b7528 100644 > > --- 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 8c55874f44ca..ed9c22dc4a5a 100644 > > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c > > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c > > @@ -17120,7 +17120,7 @@ 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 424d973c97f2..dd2b8f087163 100644 > > --- 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 5a46870c4b74..fc49aae38807 100644 > > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > > @@ -5924,7 +5924,7 @@ 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 c406a3b56b37..138e522ef9b9 100644 > > --- 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 0e1e581efc5a..580bccb118a0 100644 > > --- a/include/linux/netdevice.h > > +++ b/include/linux/netdevice.h > > @@ -1788,6 +1788,11 @@ 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 */ > > @@ -1809,7 +1814,8 @@ 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 (NETMEM_TX_NONE or > > + * NETMEM_TX_DMA). > > > nit: if you happen to repost, listing enum values here seems too much? > > "device netmem TX mode" should be enough Will do! Thanks, Bobby