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From: Doug Berger <opendmb@gmail.com>
To: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	netdev@vger.kernel.or,
	linux-kernel@vger.kernel.org,
	Doug Berger <opendmb@gmail.com>,
	stable@vger.kernel.org
Subject: [PATCH 1/3] net: bcmgenet: synchronize EXT_RGMII_OOB_CTRL access
Date: Thu, 25 Apr 2024 15:06:48 -0700
Message-Id: <20240425220650.2138801-2-opendmb@gmail.com>
In-Reply-To: <20240425220650.2138801-1-opendmb@gmail.com>
References: <20240425220650.2138801-1-opendmb@gmail.com>
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The EXT_RGMII_OOB_CTRL register can be written from different
contexts. It is predominantly written from the adjust_link
handler which is synchronized by the phydev->lock, but can
also be written from a different context when configuring the
mii in bcmgenet_mii_config().

The chances of contention are quite low, but it is conceivable
that adjust_link could occur during resume when WoL is enabled
so use the phydev->lock synchronizer in bcmgenet_mii_config()
to be sure.

Fixes: afe3f907d20f ("net: bcmgenet: power on MII block for all MII modes")
Cc: stable@vger.kernel.org
Signed-off-by: Doug Berger <opendmb@gmail.com>
---
 drivers/net/ethernet/broadcom/genet/bcmmii.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
index 9ada89355747..86a4aa72b3d4 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -2,7 +2,7 @@
 /*
  * Broadcom GENET MDIO routines
  *
- * Copyright (c) 2014-2017 Broadcom
+ * Copyright (c) 2014-2024 Broadcom
  */
 
 #include <linux/acpi.h>
@@ -275,6 +275,7 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 	 * block for the interface to work, unconditionally clear the
 	 * Out-of-band disable since we do not need it.
 	 */
+	mutex_lock(&phydev->lock);
 	reg = bcmgenet_ext_readl(priv, EXT_RGMII_OOB_CTRL);
 	reg &= ~OOB_DISABLE;
 	if (priv->ext_phy) {
@@ -286,6 +287,7 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 			reg |= RGMII_MODE_EN;
 	}
 	bcmgenet_ext_writel(priv, reg, EXT_RGMII_OOB_CTRL);
+	mutex_unlock(&phydev->lock);
 
 	if (init)
 		dev_info(kdev, "configuring instance for %s\n", phy_name);
-- 
2.34.1