From a5b9ff72cff3f25516b9c8142da9c875eb41e044 Mon Sep 17 00:00:00 2001 From: DENG Qingfang Date: Sat, 3 Apr 2021 22:59:15 +0800 Subject: [PATCH] ramips: mt7530 swconfig: fix race condition in register access The mt7530_{r,w}32 operation over MDIO uses 3 mdiobus operations and does not hold a lock, which causes a race condition when multiple threads try to access a register, they may get unexpected results. To avoid this, handle the MDIO lock manually, and use the unlocked __mdiobus_{read,write} in the critical section. This fixes the "Ghost VLAN" artifact[1] in MT7530/7621 when the VLAN operation and the swconfig LED link status poll race between each other. [1] https://forum.openwrt.org/t/mysterious-vlan-ids-on-mt7621-device/64495 Signed-off-by: DENG Qingfang --- .../drivers/net/ethernet/mediatek/mt7530.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mt7530.c b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mt7530.c index 7003f3efe4..959c777d62 100644 --- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mt7530.c +++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mt7530.c @@ -323,9 +323,11 @@ mt7530_r32(struct mt7530_priv *priv, u32 reg) if (priv->bus) { u16 high, low; - mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff); - low = mdiobus_read(priv->bus, 0x1f, (reg >> 2) & 0xf); - high = mdiobus_read(priv->bus, 0x1f, 0x10); + mutex_lock(&priv->bus->mdio_lock); + __mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff); + low = __mdiobus_read(priv->bus, 0x1f, (reg >> 2) & 0xf); + high = __mdiobus_read(priv->bus, 0x1f, 0x10); + mutex_unlock(&priv->bus->mdio_lock); return (high << 16) | (low & 0xffff); } @@ -340,9 +342,11 @@ static void mt7530_w32(struct mt7530_priv *priv, u32 reg, u32 val) { if (priv->bus) { - mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff); - mdiobus_write(priv->bus, 0x1f, (reg >> 2) & 0xf, val & 0xffff); - mdiobus_write(priv->bus, 0x1f, 0x10, val >> 16); + mutex_lock(&priv->bus->mdio_lock); + __mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff); + __mdiobus_write(priv->bus, 0x1f, (reg >> 2) & 0xf, val & 0xffff); + __mdiobus_write(priv->bus, 0x1f, 0x10, val >> 16); + mutex_unlock(&priv->bus->mdio_lock); return; }