From: Andrew Lunn <andrew@lunn.ch>
To: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel@savoirfairelinux.com,
"David S. Miller" <davem@davemloft.net>,
Florian Fainelli <f.fainelli@gmail.com>,
Guenter Roeck <linux@roeck-us.net>,
Neil Armstrong <narmstrong@baylibre.com>
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: assert SMI lock
Date: Fri, 30 Oct 2015 22:01:46 +0100 [thread overview]
Message-ID: <20151030210146.GD10053@lunn.ch> (raw)
In-Reply-To: <20151030205048.GA6658@ketchup.mtl.sfl>
> > > static int _mv88e6xxx_reg_read(struct dsa_switch *ds, int addr, int reg)
> > > {
> > > - struct mii_bus *bus = dsa_host_dev_to_mii_bus(ds->master_dev);
> > > + struct mii_bus *bus;
> > > int ret;
> > >
> > > + assert_smi_lock(ds);
> > > +
> > > + bus = dsa_host_dev_to_mii_bus(ds->master_dev);
> >
> > Is this change of when bus is assigned actually required?
>
> No, but I found not necessary to issue this "mdio_bus" lookup if the
> lock is not held (see net/dsa/dsa.c:555). Do you prefer not to do that?
You are optimising for an error condition. If this optimisation saves
anything, it means we have a locking bug!
As a separate patch, i would do this lookup once in a setup function
and save it away in ps. We just need to watch out for the probe
register accesses.
> Also are you OK with removing all the "Must be called with..." comments,
Yes, it will become a lot more clear when the kernel outputs a stack dump!
Andrew
next prev parent reply other threads:[~2015-10-30 21:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 20:35 [PATCH net-next] net: dsa: mv88e6xxx: assert SMI lock Vivien Didelot
2015-10-30 20:41 ` Andrew Lunn
2015-10-30 20:50 ` Vivien Didelot
2015-10-30 21:01 ` Andrew Lunn [this message]
2015-10-30 21:11 ` Vivien Didelot
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