linux-kernel - Re: [PATCH 14/18] dsa: ocelot: fix mixed module-builtin object

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Date:   Mon, 21 Nov 2022 19:55:04 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Alexander Lobakin <alobakin@...me>,
        Colin Foster <colin.foster@...advantage.com>
Cc:     linux-kbuild@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nicolas Schier <nicolas@...sle.eu>,
        Jens Axboe <axboe@...nel.dk>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Tony Luck <tony.luck@...el.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Derek Chickles <dchickles@...vell.com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Sunil Goutham <sgoutham@...vell.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Daniel Scally <djrscally@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Brown <broonie@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        NXP Linux Team <linux-imx@....com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/18] dsa: ocelot: fix mixed module-builtin object

On Sat, Nov 19, 2022 at 11:09:28PM +0000, Alexander Lobakin wrote:
> With CONFIG_NET_DSA_MSCC_FELIX=m and CONFIG_NET_DSA_MSCC_SEVILLE=y
> (or vice versa), felix.o are linked to a module and also to vmlinux
> even though the expected CFLAGS are different between builtins and
> modules.
> This is the same situation as fixed by
> commit 637a642f5ca5 ("zstd: Fixing mixed module-builtin objects").
> There's also no need to duplicate relatively big piece of object
> code into two modules.
> 
> Introduce the new module, mscc_core, to provide the common functions
> to both mscc_felix and mscc_seville.
> 
> Fixes: d60bc62de4ae ("net: dsa: seville: build as separate module")
> Suggested-by: Masahiro Yamada <masahiroy@...nel.org>
> Signed-off-by: Alexander Lobakin <alobakin@...me>
> ---

I don't disagree with the patch, but I dislike the name chosen.
How about NET_DSA_OCELOT_LIB and mscc_ocelot_dsa_lib.o? The "core" of
the hardware support is arguably mscc_ocelot_switch_lib.o, I don't think
it would be good to use that word here, since the code you're moving is
no more than a thin glue layer with some DSA specific code.

Adding Colin for a second opinion on the naming. I'm sure things could
have been done better in the first place, just not sure how.

Also, could you please make the commit prefix "net: dsa: ocelot" when
you resend this and the other networking patches to the "net" tree?

>  drivers/net/dsa/ocelot/Kconfig           | 18 ++++++++++--------
>  drivers/net/dsa/ocelot/Makefile          | 12 +++++-------
>  drivers/net/dsa/ocelot/felix.c           |  6 ++++++
>  drivers/net/dsa/ocelot/felix_vsc9959.c   |  2 ++
>  drivers/net/dsa/ocelot/seville_vsc9953.c |  2 ++
>  5 files changed, 25 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/dsa/ocelot/Kconfig b/drivers/net/dsa/ocelot/Kconfig
> index 08db9cf76818..59845274e374 100644
> --- a/drivers/net/dsa/ocelot/Kconfig
> +++ b/drivers/net/dsa/ocelot/Kconfig
> @@ -1,4 +1,12 @@
>  # SPDX-License-Identifier: GPL-2.0-only
> +
> +config NET_DSA_MSCC_CORE
> +	tristate
> +	select MSCC_OCELOT_SWITCH_LIB
> +	select NET_DSA_TAG_OCELOT_8021Q
> +	select NET_DSA_TAG_OCELOT
> +	select PCS_LYNX

Please keep PCS_LYNX selected by MSCC_FELIX and MSCC_SEVILLE respectively.

> +
>  config NET_DSA_MSCC_FELIX
>  	tristate "Ocelot / Felix Ethernet switch support"
>  	depends on NET_DSA && PCI
> @@ -7,11 +15,8 @@ config NET_DSA_MSCC_FELIX
>  	depends on HAS_IOMEM
>  	depends on PTP_1588_CLOCK_OPTIONAL
>  	depends on NET_SCH_TAPRIO || NET_SCH_TAPRIO=n
> -	select MSCC_OCELOT_SWITCH_LIB
> -	select NET_DSA_TAG_OCELOT_8021Q
> -	select NET_DSA_TAG_OCELOT
> +	select NET_DSA_MSCC_CORE
>  	select FSL_ENETC_MDIO
> -	select PCS_LYNX
>  	help
>  	  This driver supports the VSC9959 (Felix) switch, which is embedded as
>  	  a PCIe function of the NXP LS1028A ENETC RCiEP.
> @@ -22,11 +27,8 @@ config NET_DSA_MSCC_SEVILLE
>  	depends on NET_VENDOR_MICROSEMI
>  	depends on HAS_IOMEM
>  	depends on PTP_1588_CLOCK_OPTIONAL
> +	select NET_DSA_MSCC_CORE
>  	select MDIO_MSCC_MIIM
> -	select MSCC_OCELOT_SWITCH_LIB
> -	select NET_DSA_TAG_OCELOT_8021Q
> -	select NET_DSA_TAG_OCELOT
> -	select PCS_LYNX
>  	help
>  	  This driver supports the VSC9953 (Seville) switch, which is embedded
>  	  as a platform device on the NXP T1040 SoC.
> diff --git a/drivers/net/dsa/ocelot/Makefile b/drivers/net/dsa/ocelot/Makefile
> index f6dd131e7491..f8c74b59b996 100644
> --- a/drivers/net/dsa/ocelot/Makefile
> +++ b/drivers/net/dsa/ocelot/Makefile
> @@ -1,11 +1,9 @@
>  # SPDX-License-Identifier: GPL-2.0-only
> +
> +obj-$(CONFIG_NET_DSA_MSCC_CORE) += mscc_core.o
>  obj-$(CONFIG_NET_DSA_MSCC_FELIX) += mscc_felix.o
>  obj-$(CONFIG_NET_DSA_MSCC_SEVILLE) += mscc_seville.o
> 
> -mscc_felix-objs := \
> -	felix.o \
> -	felix_vsc9959.o
> -
> -mscc_seville-objs := \
> -	felix.o \
> -	seville_vsc9953.o
> +mscc_core-objs := felix.o
> +mscc_felix-objs := felix_vsc9959.o
> +mscc_seville-objs := seville_vsc9953.o
> diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
> index dd3a18cc89dd..f9d0a24ebc3a 100644
> --- a/drivers/net/dsa/ocelot/felix.c
> +++ b/drivers/net/dsa/ocelot/felix.c
> @@ -2112,6 +2112,7 @@ const struct dsa_switch_ops felix_switch_ops = {
>  	.port_set_host_flood		= felix_port_set_host_flood,
>  	.port_change_master		= felix_port_change_master,
>  };
> +EXPORT_SYMBOL_NS_GPL(felix_switch_ops, NET_DSA_MSCC_CORE);

What do we gain practically with the symbol namespacing?

> 
>  struct net_device *felix_port_to_netdev(struct ocelot *ocelot, int port)
>  {
> @@ -2123,6 +2124,7 @@ struct net_device *felix_port_to_netdev(struct ocelot *ocelot, int port)
> 
>  	return dsa_to_port(ds, port)->slave;
>  }
> +EXPORT_SYMBOL_NS_GPL(felix_port_to_netdev, NET_DSA_MSCC_CORE);
> 
>  int felix_netdev_to_port(struct net_device *dev)
>  {
> @@ -2134,3 +2136,7 @@ int felix_netdev_to_port(struct net_device *dev)
> 
>  	return dp->index;
>  }
> +EXPORT_SYMBOL_NS_GPL(felix_netdev_to_port, NET_DSA_MSCC_CORE);
> +
> +MODULE_DESCRIPTION("MSCC Switch driver core");

Ocelot switch DSA library

> +MODULE_LICENSE("GPL");
> diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
> index 26a35ae322d1..52c8bff79fa3 100644
> --- a/drivers/net/dsa/ocelot/felix_vsc9959.c
> +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
> @@ -2736,5 +2736,7 @@ static struct pci_driver felix_vsc9959_pci_driver = {
>  };
>  module_pci_driver(felix_vsc9959_pci_driver);
> 
> +MODULE_IMPORT_NS(NET_DSA_MSCC_CORE);
> +
>  MODULE_DESCRIPTION("Felix Switch driver");
>  MODULE_LICENSE("GPL v2");
> diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c
> index 7af33b2c685d..e9c63c642489 100644
> --- a/drivers/net/dsa/ocelot/seville_vsc9953.c
> +++ b/drivers/net/dsa/ocelot/seville_vsc9953.c
> @@ -1115,5 +1115,7 @@ static struct platform_driver seville_vsc9953_driver = {
>  };
>  module_platform_driver(seville_vsc9953_driver);
> 
> +MODULE_IMPORT_NS(NET_DSA_MSCC_CORE);
> +
>  MODULE_DESCRIPTION("Seville Switch driver");
>  MODULE_LICENSE("GPL v2");
> --
> 2.38.1
> 
>