linux-kernel - [PATCH 4.9 2/8] net: mdio: introduce a shutdown method to mdio device drivers

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Message-Id: <20211008112714.023146177@linuxfoundation.org>
Date:   Fri,  8 Oct 2021 13:27:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Oltean <vladimir.oltean@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 2/8] net: mdio: introduce a shutdown method to mdio device drivers

From: Vladimir Oltean <vladimir.oltean@....com>

[ Upstream commit cf9579976f724ad517cc15b7caadea728c7e245c ]

MDIO-attached devices might have interrupts and other things that might
need quiesced when we kexec into a new kernel. Things are even more
creepy when those interrupt lines are shared, and in that case it is
absolutely mandatory to disable all interrupt sources.

Moreover, MDIO devices might be DSA switches, and DSA needs its own
shutdown method to unlink from the DSA master, which is a new
requirement that appeared after commit 2f1e8ea726e9 ("net: dsa: link
interfaces with the DSA master to get rid of lockdep warnings").

So introduce a ->shutdown method in the MDIO device driver structure.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/phy/mdio_device.c | 11 +++++++++++
 include/linux/mdio.h          |  3 +++
 2 files changed, 14 insertions(+)

diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index 9c88e6749b9a..34600b0061bb 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/drivers/net/phy/mdio_device.c
@@ -135,6 +135,16 @@ static int mdio_remove(struct device *dev)
 	return 0;
 }
 
+static void mdio_shutdown(struct device *dev)
+{
+	struct mdio_device *mdiodev = to_mdio_device(dev);
+	struct device_driver *drv = mdiodev->dev.driver;
+	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
+
+	if (mdiodrv->shutdown)
+		mdiodrv->shutdown(mdiodev);
+}
+
 /**
  * mdio_driver_register - register an mdio_driver with the MDIO layer
  * @new_driver: new mdio_driver to register
@@ -149,6 +159,7 @@ int mdio_driver_register(struct mdio_driver *drv)
 	mdiodrv->driver.bus = &mdio_bus_type;
 	mdiodrv->driver.probe = mdio_probe;
 	mdiodrv->driver.remove = mdio_remove;
+	mdiodrv->driver.shutdown = mdio_shutdown;
 
 	retval = driver_register(&mdiodrv->driver);
 	if (retval) {
diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index bf9d1d750693..78b3cf50566f 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h
@@ -61,6 +61,9 @@ struct mdio_driver {
 
 	/* Clears up any memory if needed */
 	void (*remove)(struct mdio_device *mdiodev);
+
+	/* Quiesces the device on system shutdown, turns off interrupts etc */
+	void (*shutdown)(struct mdio_device *mdiodev);
 };
 #define to_mdio_driver(d)						\
 	container_of(to_mdio_common_driver(d), struct mdio_driver, mdiodrv)
-- 
2.33.0