[PATCH AUTOSEL 6.6 52/61] dsa: qca8k: Use nested lock to avoid splat
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From: Sasha Levin <sashal@kernel.org>
Date: 2024-11-24 13:48:51
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lkml, stable
Subsystem:
networking drivers, networking [dsa], qualcomm atheros qca8k dsa switch driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Andrew Lunn, Vladimir Oltean, Christian Marangi, Linus Torvalds
From: Andrew Lunn <andrew@lunn.ch> [ Upstream commit 078e0d596f7b5952dad8662ace8f20ed2165e2ce ] qca8k_phy_eth_command() is used to probe the child MDIO bus while the parent MDIO is locked. This causes lockdep splat, reporting a possible deadlock. It is not an actually deadlock, because different locks are used. By making use of mutex_lock_nested() we can avoid this false positive. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Link: https://patch.msgid.link/20241110175955.3053664-1-andrew@lunn.ch (local) Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/net/dsa/qca/qca8k-8xxx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
index 17c28fe2d7433..384ae32c05b1c 100644
--- a/drivers/net/dsa/qca/qca8k-8xxx.c
+++ b/drivers/net/dsa/qca/qca8k-8xxx.c@@ -673,7 +673,7 @@ qca8k_phy_eth_command(struct qca8k_priv *priv, bool read, int phy, * We therefore need to lock the MDIO bus onto which the switch is * connected. */ - mutex_lock(&priv->bus->mdio_lock); + mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED); /* Actually start the request: * 1. Send mdio master packet
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2.43.0