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dsa: qca8k: Use nested lock to avoid splat

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[ 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
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Andrew Lunn 2024-11-10 18:59:55 +01:00 committed by Greg Kroah-Hartman
parent 67a25ea28f
commit 7d9a095160
1 changed files with 1 additions and 1 deletions
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2
drivers/net/dsa/qca/qca8k-8xxx.c
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@ -551,7 +551,7 @@ 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