This is a note to let you know that I've just added the patch titled
dsa: qca8k: Use nested lock to avoid splat
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dsa-qca8k-use-nested-lock-to-avoid-splat.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d12eb0e20a56817d923beb1ce1df32026b1797d6
Author: Andrew Lunn <andrew@xxxxxxx>
Date: Sun Nov 10 18:59:55 2024 +0100
dsa: qca8k: Use nested lock to avoid splat
[ 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@xxxxxxx>
Link: https://patch.msgid.link/20241110175955.3053664-1-andrew@xxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
index 641692f716f86..47e9b2c303831 100644
--- a/drivers/net/dsa/qca/qca8k-8xxx.c
+++ b/drivers/net/dsa/qca/qca8k-8xxx.c
@@ -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
