linux-kernel - [PATCH net] net: phy: Avoid multiple suspends

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Date:   Thu, 20 Feb 2020 15:34:53 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     yoshihiro.shimoda.uh@...esas.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Fugang Duan <B38611@...escale.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net] net: phy: Avoid multiple suspends

It is currently possible for a PHY device to be suspended as part of a
network device driver's suspend call while it is still being attached to
that net_device, either via phy_suspend() or implicitly via phy_stop().

Later on, when the MDIO bus controller get suspended, we would attempt
to suspend again the PHY because it is still attached to a network
device.

This is both a waste of time and creates an opportunity for improper
clock/power management bugs to creep in.

Fixes: 803dd9c77ac3 ("net: phy: avoid suspending twice a PHY")
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
Heiner, Andrew,

I did consider adding logic that would check for phydev->suspended in
phy_suspend() and phy_resume(), but this was really the only place where
I found it to be problematic.

 drivers/net/phy/phy_device.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 6a5056e0ae77..6131aca79823 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -247,7 +247,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	 * MDIO bus driver and clock gated at this point.
 	 */
 	if (!netdev)
-		return !phydev->suspended;
+		goto out;

 	if (netdev->wol_enabled)
 		return false;
@@ -267,7 +267,8 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	if (device_may_wakeup(&netdev->dev))
 		return false;

-	return true;
+out:
+	return !phydev->suspended;
 }

 static int mdio_bus_phy_suspend(struct device *dev)
-- 
2.17.1