Re: [PATCH net-next] net: phy: link_topology: Don't stub-away the topology creation

From: Nathan Chancellor <nathan@kernel.org>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Eric Dumazet" <edumazet@google.com>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Russell King" <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	"Christophe Leroy" <christophe.leroy@csgroup.eu>,
	"Herve Codina" <herve.codina@bootlin.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Vladimir Oltean" <vladimir.oltean@nxp.com>,
	"Köry Maincent" <kory.maincent@bootlin.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"Marek Behún" <kabel@kernel.org>,
	"Piergiorgio Beruto" <piergiorgio.beruto@gmail.com>,
	"Oleksij Rempel" <o.rempel@pengutronix.de>,
	"Nicolò Veronese" <nicveronese@gmail.com>,
	"Simon Horman" <horms@kernel.org>,
	mwojtas@chromium.org, "Antoine Tenart" <atenart@kernel.org>
Subject: Re: [PATCH net-next] net: phy: link_topology: Don't stub-away the topology creation
Date: Wed, 17 Apr 2024 11:07:21 -0700	[thread overview]
Message-ID: <20240417180721.GA3212605@dev-arch.thelio-3990X> (raw)
In-Reply-To: <20240417142707.2082523-1-maxime.chevallier@bootlin.com>

Hi Maxime,

On Wed, Apr 17, 2024 at 04:27:05PM +0200, Maxime Chevallier wrote:
> Some of the phy_link_topology operations are protected by IS_REACHABLE,
> which can lead to scenarios where the consumer, built as modules, sees the topology
> unstubbed, whereas the initialization didn't occur.
> 
> Don't stub away the creation of the topology, it has no dependency on
> any other parts like phylib, so we can make it always available.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> Closes: https://lore.kernel.org/netdev/2e11b89d-100f-49e7-9c9a-834cc0b82f97@gmail.com/
> Closes: https://lore.kernel.org/netdev/20240409201553.GA4124869@dev-arch.thelio-3990X/
> ---
> Hi Nathan, Heiner,
> 
> I'm currently at EOSS, so I'm sending this patch without having been
> able to properly test it (build-tested only), but as this addresses an
> issue for people using -next, I'm sending this anyway, sorry about that.

No worries, thanks for continuing to take a look. Unfortunately, this
patch fails to build during the linking stage for me with my
configuration:

x86_64-linux-ld: vmlinux.o: in function `free_netdev':
net/core/dev.c:11060:(.text+0xb14030): undefined reference to `phy_link_topo_destroy'
x86_64-linux-ld: vmlinux.o: in function `alloc_netdev_mqs':
net/core/dev.c:10966:(.text+0xb142d6): undefined reference to `phy_link_topo_create'

> Hopefully it can address the issue for now, I haven't given-up on your
> idea to introduce a config option Heiner :)
> 
> Thanks,
> 
> Maxime
> 
>  include/linux/phy_link_topology_core.h | 15 ---------------
>  1 file changed, 15 deletions(-)
> 
> diff --git a/include/linux/phy_link_topology_core.h b/include/linux/phy_link_topology_core.h
> index 0a6479055745..61e2592f24ac 100644
> --- a/include/linux/phy_link_topology_core.h
> +++ b/include/linux/phy_link_topology_core.h
> @@ -4,22 +4,7 @@
>  
>  struct phy_link_topology;
>  
> -#if IS_REACHABLE(CONFIG_PHYLIB)
> -
>  struct phy_link_topology *phy_link_topo_create(struct net_device *dev);
>  void phy_link_topo_destroy(struct phy_link_topology *topo);
>  
> -#else
> -
> -static inline struct phy_link_topology *phy_link_topo_create(struct net_device *dev)
> -{
> -	return NULL;
> -}
> -
> -static inline void phy_link_topo_destroy(struct phy_link_topology *topo)
> -{
> -}
> -
> -#endif
> -
>  #endif /* __PHY_LINK_TOPOLOGY_CORE_H */
> -- 
> 2.44.0
> 