netdev - Re: [PATCH net-next v4 4/4] net: mdio: reset PHY before attempting to access registers in fwnode_mdiobus_register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <aQHBKitU6Gyjk37e@debianbuilder>
Date: Wed, 29 Oct 2025 08:24:26 +0100
From: Buday Csaba <buday.csaba@...lan.hu>
To: Jakub Kicinski <kuba@...nel.org>
CC: 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>, Paolo Abeni
	<pabeni@...hat.com>, Philipp Zabel <p.zabel@...gutronix.de>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v4 4/4] net: mdio: reset PHY before attempting
 to access registers in fwnode_mdiobus_register_phy

On Tue, Oct 28, 2025 at 06:26:05PM -0700, Jakub Kicinski wrote:
> On Wed, 22 Oct 2025 11:08:53 +0200 Buday Csaba wrote:
> > +/* Hard-reset a PHY before registration */
> > +static int fwnode_reset_phy(struct mii_bus *bus, u32 addr,
> > +			    struct fwnode_handle *phy_node)
> > +{
> > +	struct mdio_device *tmpdev;
> > +	int err;
> > +
> > +	tmpdev = mdio_device_create(bus, addr);
> > +	if (IS_ERR(tmpdev))
> > +		return PTR_ERR(tmpdev);
> > +
> > +	fwnode_handle_get(phy_node);
> > +	device_set_node(&tmpdev->dev, phy_node);
> > +	err = mdio_device_register_reset(tmpdev);
> > +	if (err) {
> > +		mdio_device_free(tmpdev);
> > +		return err;
> 
> Should we worry about -EPROBE_DEFER on any of the error paths here?
> If not maybe consider making this function void? We can add errors
> back if the caller starts to care.

That is a very valid point, thanks! I think I can handle that correctly,
by propagating that (or any other) error codes to the caller of
fwnode_mdiobus_register_phy(). fwnode_reset_phy() does nothing that
would not be expected to occur during the normal registration, so if
it fails here, it would fail later as well.

> 
> > +	}
> > +
> > +	if (mdio_device_has_reset(tmpdev)) {
> > +		dev_info(&bus->dev,
> > +			 "PHY device at address %d not detected, resetting PHY.",
> > +			 addr);
> 
> IDK if this is still strictly necessary but I guess \n at the end of
> the info msg would be idiomatic
> 

I will separate the error message to another patch, then the maintainers
can decide wheter to merge it or not.

Thanks for the feedback!
I should be able to send v5 soon.

Csaba