netdev - Re: [PATCH net-next v2 07/13] net: dsa: realtek: add new mdio interface for drivers

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Message-ID: <Ycrfjr7wh6IhN+rF@lunn.ch>
Date:   Tue, 28 Dec 2021 10:57:34 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Luiz Angelo Daros de Luca <luizluca@...il.com>
Cc:     Alvin Šipraga <ALSI@...g-olufsen.dk>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Arınç ÜNAL <arinc.unal@...nc9.com>
Subject: Re: [PATCH net-next v2 07/13] net: dsa: realtek: add new mdio
 interface for drivers

> > > +int realtek_mdio_read_reg(struct realtek_priv *priv, u32 addr, u32 *data)
> > > +{
> > > +     u32 phy_id = priv->phy_id;
> > > +     struct mii_bus *bus = priv->bus;
> > > +
> > > +     BUG_ON(in_interrupt());
> >
> > Again, please don't use BUG here - just make sure this never happens (it
> > looks OK to me). There is a separate warning in mutex_lock which may
> > print a stacktrace if the kernel is configured to do so.
> 
> OK. So, is it safe to simply drop it?

Yes. The MDIO core will never call this in interrupt context.

If you want to be paranoid, use might_sleep(); and build your kernel
with CONFIG_DEBUG_ATOMIC_SLEEP.

     Andrew