netdev - [PATCH net 1/6] iavf: iavf_suspend(): take RTNL before netdev

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Message-ID: <20250603171710.2336151-2-anthony.l.nguyen@intel.com>
Date: Tue,  3 Jun 2025 10:17:02 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	andrew+netdev@...n.ch,
	netdev@...r.kernel.org
Cc: Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	anthony.l.nguyen@...el.com,
	sdf@...ichev.me,
	sassmann@...nic.de,
	Jacob Keller <jacob.e.keller@...el.com>,
	Rafal Romanowski <rafal.romanowski@...el.com>
Subject: [PATCH net 1/6] iavf: iavf_suspend(): take RTNL before netdev_lock()

From: Przemek Kitszel <przemyslaw.kitszel@...el.com>

Fix an obvious violation of lock ordering.
Jakub's [1] added netdev_lock() call that is wrong ordered wrt RTNL,
but the Fixes tag points to crit_lock being wrongly placed (by lockdep
standards).

Actual reason we got it wrong is dated back to critical section managed by
pure flag checks, which is with us since the very beginning.

[1] afc664987ab3 ("eth: iavf: extend the netdev_lock usage")

Fixes: 5ac49f3c2702 ("iavf: use mutexes for locking of critical sections")
Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
Tested-by: Rafal Romanowski <rafal.romanowski@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/iavf/iavf_main.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 6d7ba4d67a19..a77c72643528 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -5596,22 +5596,27 @@ static int iavf_suspend(struct device *dev_d)
 {
 	struct net_device *netdev = dev_get_drvdata(dev_d);
 	struct iavf_adapter *adapter = netdev_priv(netdev);
+	bool running;
 
 	netif_device_detach(netdev);
 
+	running = netif_running(netdev);
+	if (running)
+		rtnl_lock();
+
 	netdev_lock(netdev);
 	mutex_lock(&adapter->crit_lock);
 
-	if (netif_running(netdev)) {
-		rtnl_lock();
+	if (running)
 		iavf_down(adapter);
-		rtnl_unlock();
-	}
+
 	iavf_free_misc_irq(adapter);
 	iavf_reset_interrupt_capability(adapter);
 
 	mutex_unlock(&adapter->crit_lock);
 	netdev_unlock(netdev);
+	if (running)
+		rtnl_unlock();
 
 	return 0;
 }
-- 
2.47.1