linux-kernel - Re: [PATCH net-next v2] net: phy: Add driver for Motorcomm yt8531 gigabit ethernet phy

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Date:   Fri, 2 Dec 2022 13:34:16 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Frank <Frank.Sae@...or-comm.com>, Peter Geis <pgwipeout@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, yinghong.zhang@...or-comm.com,
        fei.zhang@...or-comm.com, hua.sun@...or-comm.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2] net: phy: Add driver for Motorcomm yt8531
 gigabit ethernet phy

On Fri, Dec 02, 2022 at 02:27:43PM +0100, Andrew Lunn wrote:
> > +static bool mdio_is_locked(struct phy_device *phydev)
> > +{
> > +	return mutex_is_locked(&phydev->mdio.bus->mdio_lock);
> > +}
> > +
> > +#define ASSERT_MDIO(phydev) \
> > +	WARN_ONCE(!mdio_is_locked(phydev), \
> > +		  "MDIO: assertion failed at %s (%d)\n", __FILE__,  __LINE__)
> > +
> 
> Hi Frank
> 
> You are not the only one who gets locking wrong. This could be used in
> other drivers. Please add it to include/linux/phy.h,

That placement doesn't make much sense.

As I already said, we have lockdep checks in drivers/net/phy/mdio_bus.c,
and if we want to increase their effectiveness, then that's the place
that it should be done.

I don't see any point in using __FILE__ and __LINE__ in the above
macro either. Firstly, WARN_ONCE() already includes the file and line,
and secondly, the backtrace is more useful than the file and line where
the assertion occurs especially if it's placed in mdio_bus.c

-- 
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