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From:   Quentin Schulz <quentin.schulz@bootlin.com>
To:     davem@davemloft.net, andrew@lunn.ch, f.fainelli@gmail.com
Cc:     allan.nielsen@microchip.com, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, thomas.petazzoni@bootlin.com,
        alexandre.belloni@bootlin.com,
        Quentin Schulz <quentin.schulz@bootlin.com>
Subject: [PATCH net] net: phy: mscc: fix deadlock in vsc85xx_default_config
Date:   Thu, 22 Nov 2018 14:12:32 +0100
Message-Id: <20181122131232.32032-1-quentin.schulz@bootlin.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The vsc85xx_default_config function called in the vsc85xx_config_init
function which is used by VSC8530, VSC8531, VSC8540 and VSC8541 PHYs
mistakenly calls phy_read and phy_write in-between phy_select_page and
phy_restore_page.

phy_select_page and phy_restore_page actually take and release the MDIO
bus lock so __phy_write and __phy_read (which assume that you already
have the MDIO bus lock unlike phy_write and phy_read) should be used for
any call in between the two said functions.

Let's fix this deadlock.

Fixes: 6a0bfbbe20b0 ("net: phy: mscc: migrate to phy_select/restore_page functions")

Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>
---
 drivers/net/phy/mscc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
index 62269e578718..6856fe4d1a60 100644
--- a/drivers/net/phy/mscc.c
+++ b/drivers/net/phy/mscc.c
@@ -814,10 +814,10 @@ static int vsc85xx_default_config(struct phy_device *phydev)
 	if (rc < 0)
 		goto out_unlock;
 
-	reg_val = phy_read(phydev, MSCC_PHY_RGMII_CNTL);
+	reg_val = __phy_read(phydev, MSCC_PHY_RGMII_CNTL);
 	reg_val &= ~(RGMII_RX_CLK_DELAY_MASK);
 	reg_val |= (RGMII_RX_CLK_DELAY_1_1_NS << RGMII_RX_CLK_DELAY_POS);
-	phy_write(phydev, MSCC_PHY_RGMII_CNTL, reg_val);
+	__phy_write(phydev, MSCC_PHY_RGMII_CNTL, reg_val);
 
 out_unlock:
 	rc = phy_restore_page(phydev, rc, rc > 0 ? 0 : rc);
-- 
2.17.1