Re: ordering of call to unbind() in usbnet_disconnect

From: Andrew Lunn <andrew@lunn.ch>
To: Lukas Wunner <lukas@wunner.de>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>,
	Oliver Neukum <oneukum@suse.com>,
	Oleksij Rempel <linux@rempel-privat.de>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: ordering of call to unbind() in usbnet_disconnect
Date: Mon, 14 Mar 2022 20:14:36 +0100	[thread overview]
Message-ID: <Yi+UHF37rb0URSwb@lunn.ch> (raw)
In-Reply-To: <20220314184234.GA556@wunner.de>

On Mon, Mar 14, 2022 at 07:42:34PM +0100, Lukas Wunner wrote:
> [cc += Heiner Kallweit, Andrew Lunn]
> 
> On Thu, Mar 10, 2022 at 12:38:20PM +0100, Oleksij Rempel wrote:
> > On Thu, Mar 10, 2022 at 12:25:08PM +0100, Oliver Neukum wrote:
> > > I got bug reports that 2c9d6c2b871d ("usbnet: run unbind() before
> > > unregister_netdev()")
> > > is causing regressions.
> 
> I would like to see this reverted as well.  For obvious reasons,
> the order in usbnet_disconnect() should be the inverse of
> usbnet_probe().  Since 2c9d6c2b871d, that's no longer the case.
> 
> 
> > > Rather than simply reverting it,
> > > it seems to me that the call needs to be split. One in the old place
> > > and one in the place you moved it to.
> 
> I disagree.  The commit message claims that the change is necessary
> because phy_disconnect() fails if called with phydev->attached_dev == NULL.

The only place i see which sets phydev->attached_dev is
phy_attach_direct(). So if phydev->attached_dev is NULL, the PHY has
not been attached, and hence there is no need to call
phy_disconnect().

	Andrew