Re: [PATCH net-next] net: build all switchdev drivers as modules when the bridge is a module

[Anders Roxell <anders.roxell@linaro.org>]

On Mon, 26 Jul 2021 at 16:26, Vladimir Oltean <vladimir.oltean@nxp.com> wrote:
>
> Currently, all drivers depend on the bool CONFIG_NET_SWITCHDEV, but only
> the drivers that call some sort of function exported by the bridge, like
> br_vlan_enabled() or whatever, have an extra dependency on CONFIG_BRIDGE.
>
> Since the blamed commit, all switchdev drivers have a functional
> dependency upon switchdev_bridge_port_{,un}offload(), which is a pair of
> functions exported by the bridge module and not by the bridge-independent
> part of CONFIG_NET_SWITCHDEV.
>
> Problems appear when we have:
>
> CONFIG_BRIDGE=m
> CONFIG_NET_SWITCHDEV=y
> CONFIG_TI_CPSW_SWITCHDEV=y
>
> because cpsw, am65_cpsw and sparx5 will then be built-in but they will
> call a symbol exported by a loadable module. This is not possible and
> will result in the following build error:
>
> drivers/net/ethernet/ti/cpsw_new.o: in function `cpsw_netdevice_event':
> drivers/net/ethernet/ti/cpsw_new.c:1520: undefined reference to
>                                         `switchdev_bridge_port_offload'
> drivers/net/ethernet/ti/cpsw_new.c:1537: undefined reference to
>                                         `switchdev_bridge_port_unoffload'
>
> As mentioned, the other switchdev drivers don't suffer from this because
> switchdev_bridge_port_offload() is not the first symbol exported by the
> bridge that they are calling, so they already needed to deal with this
> in the same way.
>
> Fixes: 2f5dc00f7a3e ("net: bridge: switchdev: let drivers inform which bridge ports are offloaded")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Thank you for providing this fix.

Tested building omap2plus_defconfig.

Tested-by: Anders Roxell <anders.roxell@linaro.org>

Cheers,
Anders

> ---
>  drivers/net/ethernet/microchip/sparx5/Kconfig | 1 +
>  drivers/net/ethernet/ti/Kconfig               | 2 ++
>  2 files changed, 3 insertions(+)
>
> diff --git a/drivers/net/ethernet/microchip/sparx5/Kconfig b/drivers/net/ethernet/microchip/sparx5/Kconfig
> index 7bdbb2d09a14..d39ae2a6fb49 100644
> --- a/drivers/net/ethernet/microchip/sparx5/Kconfig
> +++ b/drivers/net/ethernet/microchip/sparx5/Kconfig
> @@ -1,5 +1,6 @@
>  config SPARX5_SWITCH
>         tristate "Sparx5 switch driver"
> +       depends on BRIDGE || BRIDGE=n
>         depends on NET_SWITCHDEV
>         depends on HAS_IOMEM
>         depends on OF
> diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
> index affcf92cd3aa..7ac8e5ecbe97 100644
> --- a/drivers/net/ethernet/ti/Kconfig
> +++ b/drivers/net/ethernet/ti/Kconfig
> @@ -64,6 +64,7 @@ config TI_CPSW
>  config TI_CPSW_SWITCHDEV
>         tristate "TI CPSW Switch Support with switchdev"
>         depends on ARCH_DAVINCI || ARCH_OMAP2PLUS || COMPILE_TEST
> +       depends on BRIDGE || BRIDGE=n
>         depends on NET_SWITCHDEV
>         depends on TI_CPTS || !TI_CPTS
>         select PAGE_POOL
> @@ -109,6 +110,7 @@ config TI_K3_AM65_CPSW_NUSS
>  config TI_K3_AM65_CPSW_SWITCHDEV
>         bool "TI K3 AM654x/J721E CPSW Switch mode support"
>         depends on TI_K3_AM65_CPSW_NUSS
> +       depends on BRIDGE || BRIDGE=n
>         depends on NET_SWITCHDEV
>         help
>          This enables switchdev support for TI K3 CPSWxG Ethernet
> --
> 2.25.1
>