linux-kernel - Re: [PATCH v2 2/8] phy: mvebu-cp110-comphy: fix port check in ->xlate()

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Message-ID: <20181202203509.21b067c4@xps13>
Date:   Sun, 2 Dec 2018 20:35:09 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Gregory Clement <gregory.clement@...tlin.com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>,
        linux-kernel@...r.kernel.org,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/8] phy: mvebu-cp110-comphy: fix port check in
 ->xlate()

Hi Russell,

Russell King - ARM Linux <linux@...linux.org.uk> wrote on Fri, 30 Nov
2018 19:00:31 +0000:

> On Fri, Nov 30, 2018 at 03:47:37PM +0100, Miquel Raynal wrote:
> > So far the PHY ->xlate() callback was checking if the port was
> > "invalid" before continuing, meaning that the port has not been used
> > yet. This check is not correct as there is no opposite call to  
> > ->xlate() once the PHY is released by the user and the port will  
> > remain "valid" after the first phy_get()/phy_put() calls. Hence, if
> > this driver is built as a module, inserted, removed and inserted
> > again, the PHY will appear busy and the second probe will fail.
> > 
> > To fix this, just drop the faulty check and instead verify that the
> > port number is valid (ie. in the possible range).
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> > ---
> >  drivers/phy/marvell/phy-mvebu-cp110-comphy.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/phy/marvell/phy-mvebu-cp110-comphy.c b/drivers/phy/marvell/phy-mvebu-cp110-comphy.c
> > index 31b9a1c18345..a40b876ff214 100644
> > --- a/drivers/phy/marvell/phy-mvebu-cp110-comphy.c
> > +++ b/drivers/phy/marvell/phy-mvebu-cp110-comphy.c
> > @@ -567,9 +567,9 @@ static struct phy *mvebu_comphy_xlate(struct device *dev,
> >  		return phy;
> >  
> >  	lane = phy_get_drvdata(phy);
> > -	if (lane->port >= 0)
> > -		return ERR_PTR(-EBUSY);
> >  	lane->port = args->args[0];
> > +	if (lane->port >= MVEBU_COMPHY_PORTS)
> > +		return ERR_PTR(-EINVAL);  
> 
> Shouldn't we validate args->args[0] before doing anything?
> 

I don't understand your point, there is a check on args->args[0] as
we check its value (through lane->port) right after. What do you
have in mind?


Thanks,
Miquèl