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 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