netdev - Re: [PATCH v2 net-next 01/15] net: mdio-regmap: permit working with non-MMIO regmaps

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Message-ID: <20260122134704.pxeikyk4q7nhay55@skbuf>
Date: Thu, 22 Jan 2026 15:47:04 +0200
From: Vladimir Oltean <vladimir.oltean@....com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linux-kernel@...r.kernel.org,
	Herve Codina <herve.codina@...tlin.com>,
	Mark Brown <broonie@...nel.org>,
	Serge Semin <fancer.lancer@...il.com>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
	Choong Yong Liang <yong.liang.choong@...ux.intel.com>,
	Jiawen Wu <jiawenwu@...stnetic.com>
Subject: Re: [PATCH v2 net-next 01/15] net: mdio-regmap: permit working with
 non-MMIO regmaps

On Thu, Jan 22, 2026 at 02:13:01PM +0200, Vladimir Oltean wrote:
> > >  struct mdio_regmap_priv {
> > >  	struct regmap *regmap;
> > > +	unsigned int base;
> > 
> > Hmm... resource_size_t ?
> 
> Well, regmap_read() takes "unsigned int reg".
> https://elixir.bootlin.com/linux/v6.18.6/source/include/linux/regmap.h#L1297
> So in practice, a truncation will be done somewhere if the register base
> exceeds unsigned int storage capacity. But I didn't feel that it's worth
> handling that.

Would this address your feedback?

diff --git a/drivers/net/mdio/mdio-regmap.c b/drivers/net/mdio/mdio-regmap.c
index 2a0e9c519fa3..416ff4e13e8f 100644
--- a/drivers/net/mdio/mdio-regmap.c
+++ b/drivers/net/mdio/mdio-regmap.c
@@ -67,8 +67,15 @@ struct mii_bus *devm_mdio_regmap_register(struct device *dev,
 	mr = mii->priv;
 	mr->regmap = config->regmap;
 	mr->valid_addr = config->valid_addr;
-	if (config->resource)
+	if (config->resource) {
+		if (config->resource->start > U32_MAX ||
+		    config->resource->end > U32_MAX) {
+			dev_err(config->parent,
+				"Resource exceeds regmap API addressing possibilities\n");
+			return ERR_PTR(-EINVAL);
+		}
 		mr->base = config->resource->start;
+	}
 
 	mii->name = DRV_NAME;
 	strscpy(mii->id, config->name, MII_BUS_ID_SIZE);

(needs to be replicated in a bunch of other places)