netdev - [PATCH RFC net-next 2/5] net: stmmac: remove redundant racy tear-down in stmmac_dvr

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Message-Id: <E1tnfRj-0057SF-9t@rmk-PC.armlinux.org.uk>
Date: Thu, 27 Feb 2025 15:05:07 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Jon Hunter <jonathanh@...dia.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>,
	Thierry Reding <treding@...dia.com>
Subject: [PATCH RFC net-next 2/5] net: stmmac: remove redundant racy tear-down
 in stmmac_dvr_remove()

While the network device is registered, it is published to userspace,
and thus userspace can change its state. This means calling
functions such as stmmac_stop_all_dma() and stmmac_mac_set() are
racy.

Moreover, unregister_netdev() will unpublish the network device, and
then if appropriate call the .ndo_stop() method, which is
stmmac_release(). This will first call phylink_stop() which will
synchronously take the link down, resulting in stmmac_mac_link_down()
and stmmac_mac_set(, false) being called.

stmmac_release() will also call stmmac_stop_all_dma().

Consequently, neither of these two functions need to called prior
to unregister_netdev() as that will safely call paths that will
result in this work being done if necessary.

Remove these redundant racy calls.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 84d8b1c9f6d4..9462d05c40c8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -7757,8 +7757,6 @@ void stmmac_dvr_remove(struct device *dev)

 	pm_runtime_get_sync(dev);

-	stmmac_stop_all_dma(priv);
-	stmmac_mac_set(priv, priv->ioaddr, false);
 	unregister_netdev(ndev);

 #ifdef CONFIG_DEBUG_FS
-- 
2.30.2