linux-kernel - Re: [PATCH 4.9 181/310] net: phy: micrel: Restore led_mode and clk

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Date:   Thu, 12 Jul 2018 08:27:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Dan Rue <dan.rue@...aro.org>
Cc:     Leonard Crestez <leonard.crestez@....com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Grygorii Strashko <grygorii.strashko@...com>,
        open list <linux-kernel@...r.kernel.org>,
        linux- stable <stable@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...rosoft.com>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        chris.ruehl@...ys.com.hk, Lars Persson <lars.persson@...s.com>
Subject: Re: [PATCH 4.9 181/310] net: phy: micrel: Restore led_mode and
 clk_sel on resume

On Wed, Jul 11, 2018 at 08:15:48PM +0000, Dan Rue wrote:
> On Thu, Apr 19, 2018 at 10:05:24PM +0300, Leonard Crestez wrote:
> > On Thu, 2018-04-19 at 11:32 -0700, Florian Fainelli wrote:
> > > +Others who reported the same problem
> > > On 04/19/2018 11:24 AM, Naresh Kamboju wrote:
> > > > On 19 April 2018 at 21:41, Leonard Crestez <leonard.crestez@....com> wrote:
> > > > > 
> > > > > Looking at this dump I'm guessing that phydev->priv is NULL at the
> > > > > start of kszphy_config_reset and this really shouldn't be happening.
> > > > > 
> > > > > The phydev->priv field is initialized by kszphy_probe but your
> > > > > particular phy (KSZ9031) in linux-4.9.y does not seem to have .probe =
> > > > > kszphy_probe assigned in the struct phy_driver ksphy_driver array.
> > > > > 
> > > > > In upstream this was added by commit bfe72442578b ("net: phy: micrel:
> > > > > fix crash when statistic requested for KSZ9031 phy"). The message for
> > > > > that patch claims to fix a kernel crash on this command:
> > > > > 
> > > > >     ethtool --phy-statistics eth0
> > > > > 
> > > > > Looking at the code this issue should affect linux-4.9.y on your board.
> > > > > Naresh: can you please check?
> > > > After reverting the patch i have run this command and kernel oops
> > > > showed up.
> > > > ethtool --phy-statistics eth0
> > > > 
> > > > PC is at kszphy_get_stats+0x74/0xa8
> > > > 
> > > > ethtool --phy-statistics eth0 crashed on x15
> > > > 
> > > Chris proposed the following patch, which has not been formally
> > > submitted yet:
> > > 
> > > Meanwhile, Greg seems to have reverted the offending patch, so we should
> > > be good with 4.9.95.
> > 
> > I don't object to reverting my patch from linux-4.14.y but it seems all
> > the affected hardware would also be affected by the crash from ethtool
> > --phy-statistics eth0. Adding bfe72442578b to stable would be great
> > because it fixes more than the patch in the title.
> > 
> > In the other thread there is a mention that "Micrel KSZ8795",
> > "Micrel KSZ886X Switch", "Micrel KSZ8061", and "Micrel KS8737" might
> > still have problems after bfe72442578b. Is this because they have
> > kszphy_config_init but not kszphy_probe? All versions of
> > kszphy_config_init seem to check for a NULL priv.
> 
> To conclude this thread, bfe72442578b has been backported as of 4.9.112
> and 'ethtool --phy-statistics eth0' no longer causes a NULL pointer
> error.

Wonderful, thanks for confirming this.

greg k-h