Patch "net: phy: fix resume handling" has been added to the 4.14-stable tree

Patch "net: phy: fix resume handling" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net: phy: fix resume handling

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-phy-fix-resume-handling.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Feb 28 16:23:28 CET 2018
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 12 Dec 2017 10:45:36 +0000
Subject: net: phy: fix resume handling

From: Russell King <rmk+kernel@armlinux.org.uk>


[ Upstream commit f5e64032a799d4f54decc7eb6aafcdffb67f9ad9 ]

When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes
to other registers, or reset the registers to power-on defaults.
Micrel PHYs do this for their interrupt registers.

The current structure of phylib tries to enable interrupts before
resuming (and releasing) the BMCR_PDOWN bit.  This fails, causing
Micrel PHYs to stop working after a suspend/resume sequence if they
are using interrupts.

Fix this by ensuring that the PHY driver resume methods do not take
the phydev->lock mutex themselves, but the callers of phy_resume()
take that lock.  This then allows us to move the call to phy_resume()
before we enable interrupts in phy_start().

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/phy/at803x.c     |    4 ----
 drivers/net/phy/phy.c        |    9 +++------
 drivers/net/phy/phy_device.c |   10 ++++++----
 3 files changed, 9 insertions(+), 14 deletions(-)

--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -239,14 +239,10 @@ static int at803x_resume(struct phy_devi
 {
 	int value;
 
-	mutex_lock(&phydev->lock);
-
 	value = phy_read(phydev, MII_BMCR);
 	value &= ~(BMCR_PDOWN | BMCR_ISOLATE);
 	phy_write(phydev, MII_BMCR, value);
 
-	mutex_unlock(&phydev->lock);
-
 	return 0;
 }
 
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -828,7 +828,6 @@ EXPORT_SYMBOL(phy_stop);
  */
 void phy_start(struct phy_device *phydev)
 {
-	bool do_resume = false;
 	int err = 0;
 
 	mutex_lock(&phydev->lock);
@@ -841,6 +840,9 @@ void phy_start(struct phy_device *phydev
 		phydev->state = PHY_UP;
 		break;
 	case PHY_HALTED:
+		/* if phy was suspended, bring the physical link up again */
+		phy_resume(phydev);
+
 		/* make sure interrupts are re-enabled for the PHY */
 		if (phydev->irq != PHY_POLL) {
 			err = phy_enable_interrupts(phydev);
@@ -849,17 +851,12 @@ void phy_start(struct phy_device *phydev
 		}
 
 		phydev->state = PHY_RESUMING;
-		do_resume = true;
 		break;
 	default:
 		break;
 	}
 	mutex_unlock(&phydev->lock);
 
-	/* if phy was suspended, bring the physical link up again */
-	if (do_resume)
-		phy_resume(phydev);
-
 	phy_trigger_machine(phydev, true);
 }
 EXPORT_SYMBOL(phy_start);
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -135,7 +135,9 @@ static int mdio_bus_phy_resume(struct de
 	if (!mdio_bus_phy_may_suspend(phydev))
 		goto no_resume;
 
+	mutex_lock(&phydev->lock);
 	ret = phy_resume(phydev);
+	mutex_unlock(&phydev->lock);
 	if (ret < 0)
 		return ret;
 
@@ -1026,7 +1028,9 @@ int phy_attach_direct(struct net_device
 	if (err)
 		goto error;
 
+	mutex_lock(&phydev->lock);
 	phy_resume(phydev);
+	mutex_unlock(&phydev->lock);
 	phy_led_triggers_register(phydev);
 
 	return err;
@@ -1157,6 +1161,8 @@ int phy_resume(struct phy_device *phydev
 	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
 	int ret = 0;
 
+	WARN_ON(!mutex_is_locked(&phydev->lock));
+
 	if (phydev->drv && phydrv->resume)
 		ret = phydrv->resume(phydev);
 
@@ -1639,13 +1645,9 @@ int genphy_resume(struct phy_device *phy
 {
 	int value;
 
-	mutex_lock(&phydev->lock);
-
 	value = phy_read(phydev, MII_BMCR);
 	phy_write(phydev, MII_BMCR, value & ~BMCR_PDOWN);
 
-	mutex_unlock(&phydev->lock);
-
 	return 0;
 }
 EXPORT_SYMBOL(genphy_resume);


Patches currently in stable-queue which might be from rmk+kernel@armlinux.org.uk are

queue-4.14/arm-8731-1-fix-csum_partial_copy_from_user-stack-mismatch.patch
queue-4.14/net-phy-fix-resume-handling.patch

Re: Patch "net: phy: fix resume handling" has been added to the 4.14-stable tree

[Andrew Lunn]

> When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes
> to other registers, or reset the registers to power-on defaults.
> Micrel PHYs do this for their interrupt registers.
> 
> The current structure of phylib tries to enable interrupts before
> resuming (and releasing) the BMCR_PDOWN bit.  This fails, causing
> Micrel PHYs to stop working after a suspend/resume sequence if they
> are using interrupts.
> 
> Fix this by ensuring that the PHY driver resume methods do not take
> the phydev->lock mutex themselves, but the callers of phy_resume()
> take that lock.  This then allows us to move the call to phy_resume()
> before we enable interrupts in phy_start().

Hi Greg

This patch introduces some issues. You don't want this patch on its
own, you want it in combination with:

Fixes: 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")

Which went into David Millers net tree yesterday and should be making
its way towards stable.

I suggest you hold off on this patch, until you can do both at the
same time.

  Andrew

Re: Patch "net: phy: fix resume handling" has been added to the 4.14-stable tree

[Greg KH]

On Wed, Feb 28, 2018 at 04:43:48PM +0100, Andrew Lunn wrote:
> > When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes
> > to other registers, or reset the registers to power-on defaults.
> > Micrel PHYs do this for their interrupt registers.
> > 
> > The current structure of phylib tries to enable interrupts before
> > resuming (and releasing) the BMCR_PDOWN bit.  This fails, causing
> > Micrel PHYs to stop working after a suspend/resume sequence if they
> > are using interrupts.
> > 
> > Fix this by ensuring that the PHY driver resume methods do not take
> > the phydev->lock mutex themselves, but the callers of phy_resume()
> > take that lock.  This then allows us to move the call to phy_resume()
> > before we enable interrupts in phy_start().
> 
> Hi Greg
> 
> This patch introduces some issues. You don't want this patch on its
> own, you want it in combination with:
> 
> Fixes: 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")
> 
> Which went into David Millers net tree yesterday and should be making
> its way towards stable.
> 
> I suggest you hold off on this patch, until you can do both at the
> same time.

Thanks for letting me know, I've now dropped this.

greg k-h

Re: Patch "net: phy: fix resume handling" has been added to the 4.14-stable tree

[Greg KH]

On Wed, Feb 28, 2018 at 05:27:34PM +0100, Greg KH wrote:
> On Wed, Feb 28, 2018 at 04:43:48PM +0100, Andrew Lunn wrote:
> > > When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes
> > > to other registers, or reset the registers to power-on defaults.
> > > Micrel PHYs do this for their interrupt registers.
> > > 
> > > The current structure of phylib tries to enable interrupts before
> > > resuming (and releasing) the BMCR_PDOWN bit.  This fails, causing
> > > Micrel PHYs to stop working after a suspend/resume sequence if they
> > > are using interrupts.
> > > 
> > > Fix this by ensuring that the PHY driver resume methods do not take
> > > the phydev->lock mutex themselves, but the callers of phy_resume()
> > > take that lock.  This then allows us to move the call to phy_resume()
> > > before we enable interrupts in phy_start().
> > 
> > Hi Greg
> > 
> > This patch introduces some issues. You don't want this patch on its
> > own, you want it in combination with:
> > 
> > Fixes: 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")
> > 
> > Which went into David Millers net tree yesterday and should be making
> > its way towards stable.
> > 
> > I suggest you hold off on this patch, until you can do both at the
> > same time.
> 
> Thanks for letting me know, I've now dropped this.

And now both are queued up for 4.14.y, thanks.

greg k-h