netdev - [PATCH v8 net-next 10/12] net: transfer rtnl_lock() requirement from ethtool_set_ethtool_phy

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Date: Mon, 17 Jul 2023 18:27:07 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	Maxim Georgiev <glipus@...il.com>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Köry Maincent <kory.maincent@...tlin.com>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Richard Cochran <richardcochran@...il.com>,
	Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
	Gerhard Engleder <gerhard@...leder-embedded.com>,
	Hangbin Liu <liuhangbin@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Jacob Keller <jacob.e.keller@...el.com>,
	Jay Vosburgh <j.vosburgh@...il.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	Wei Fang <wei.fang@....com>,
	Shenwei Wang <shenwei.wang@....com>,
	Clark Wang <xiaoning.wang@....com>,
	NXP Linux Team <linux-imx@....com>,
	UNGLinuxDriver@...rochip.com,
	Lars Povlsen <lars.povlsen@...rochip.com>,
	Steen Hegelund <Steen.Hegelund@...rochip.com>,
	Daniel Machon <daniel.machon@...rochip.com>,
	Simon Horman <simon.horman@...igine.com>,
	Casper Andersson <casper.casan@...il.com>,
	Sergey Organov <sorganov@...il.com>,
	Michal Kubecek <mkubecek@...e.cz>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v8 net-next 10/12] net: transfer rtnl_lock() requirement from ethtool_set_ethtool_phy_ops() to caller

phy_init() and phy_exit() will have to do more stuff under rtnl_lock()
in a future change. Since rtnl_unlock() -> netdev_run_todo() does a lot
of stuff under the hood, it's a pity to lock and unlock the rtnetlink
mutex twice in a row.

Change the calling convention such that the only caller of
ethtool_set_ethtool_phy_ops(), phy_device.c, provides a context where
the rtnl_mutex is already acquired.

Note that phy_exit() wasn't performing the opposite teardown of
phy_init(). Reverse mdio_bus_init() with ethtool_set_ethtool_phy_ops(),
so that this is now the case.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
Changes in v8:
- Patch is new

 drivers/net/phy/phy_device.c | 8 +++++++-
 net/ethtool/common.c         | 3 +--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0c2014accba7..ab53d10f1844 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -30,6 +30,7 @@
 #include <linux/phy_led_triggers.h>
 #include <linux/pse-pd/pse.h>
 #include <linux/property.h>
+#include <linux/rtnetlink.h>
 #include <linux/sfp.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
@@ -3451,11 +3452,14 @@ static int __init phy_init(void)
 {
 	int rc;
 
+	rtnl_lock();
+	ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
+	rtnl_unlock();
+
 	rc = mdio_bus_init();
 	if (rc)
 		return rc;
 
-	ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
 	features_init();
 
 	rc = phy_driver_register(&genphy_c45_driver, THIS_MODULE);
@@ -3477,7 +3481,9 @@ static void __exit phy_exit(void)
 	phy_driver_unregister(&genphy_c45_driver);
 	phy_driver_unregister(&genphy_driver);
 	mdio_bus_exit();
+	rtnl_lock();
 	ethtool_set_ethtool_phy_ops(NULL);
+	rtnl_unlock();
 }
 
 subsys_initcall(phy_init);
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 5fb19050991e..f5598c5f50de 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -665,9 +665,8 @@ const struct ethtool_phy_ops *ethtool_phy_ops;
 
 void ethtool_set_ethtool_phy_ops(const struct ethtool_phy_ops *ops)
 {
-	rtnl_lock();
+	ASSERT_RTNL();
 	ethtool_phy_ops = ops;
-	rtnl_unlock();
 }
 EXPORT_SYMBOL_GPL(ethtool_set_ethtool_phy_ops);
 
-- 
2.34.1