linux-kernel - Re: [PATCH net-next v6 4/7] net: stmmac: introduce pcs_init/pcs

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Message-ID: <20240511181119.GU2347895@kernel.org>
Date: Sat, 11 May 2024 19:11:19 +0100
From: Simon Horman <horms@...nel.org>
To: Romain Gantois <romain.gantois@...tlin.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Clément Léger <clement.leger@...tlin.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH net-next v6 4/7] net: stmmac: introduce pcs_init/pcs_exit
 stmmac operations

On Fri, May 10, 2024 at 09:38:11AM +0200, Romain Gantois wrote:
> From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
> 
> Introduce a mechanism whereby platforms can create their PCS instances
> prior to the network device being published to userspace, but after
> some of the core stmmac initialisation has been completed. This means
> that the data structures that platforms need will be available.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> Reviewed-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
> Reviewed-by: Serge Semin <fancer.lancer@...il.com>
> Co-developed-by: Romain Gantois <romain.gantois@...tlin.com>
> Signed-off-by: Romain Gantois <romain.gantois@...tlin.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c | 8 +++++++-
>  include/linux/stmmac.h                            | 2 ++
>  2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> index 778d79cdb2e6d..f562c563aab55 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> @@ -505,7 +505,10 @@ int stmmac_pcs_setup(struct net_device *ndev)
>  	priv = netdev_priv(ndev);
>  	mode = priv->plat->phy_interface;
>  
> -	if (priv->plat->mdio_bus_data && priv->plat->mdio_bus_data->has_xpcs) {
> +	if (priv->plat->pcs_init) {
> +		ret = priv->plat->pcs_init(priv);
> +	} else if (priv->plat->mdio_bus_data &&
> +		   priv->plat->mdio_bus_data->has_xpcs) {
>  		/* Try to probe the XPCS by scanning all addresses */
>  		for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
>  			xpcs = xpcs_create_mdiodev(priv->mii, addr, mode);

I am unsure if this can occur, but if priv->plat->pcs_init returns 0 then
xpcs will be used while uninitialised towards the end of this function.

Flagged by Smatch.

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