e1000: fix concurrent accesses to PHY from watchdog and ethtool

The e1000 driver currently does not protect concurrent accesses to the PHY
from both the ethtool callbacks, and from the e1000_watchdog function. This
patchs adds a new spinlock which is used by e1000_{read,write}_phy_reg in
order to serialize concurrent accesses to the PHY.
Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Florian Fainelli <ffainelli@freebox.fr>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000/e1000_hw.c

@@ -107,6 +107,7 @@ u16 e1000_igp_cable_length_table[IGP01E1000_AGC_LENGTH_TABLE_SIZE] = {
 };
 
 static DEFINE_SPINLOCK(e1000_eeprom_lock);
+static DEFINE_SPINLOCK(e1000_phy_lock);
 
 /**
  * e1000_set_phy_type - Set the phy type member in the hw struct.
@@ -2830,19 +2831,25 @@ static u16 e1000_shift_in_mdi_bits(struct e1000_hw *hw)
 s32 e1000_read_phy_reg(struct e1000_hw *hw, u32 reg_addr, u16 *phy_data)
 {
 	u32 ret_val;
+	unsigned long flags;
 
 	e_dbg("e1000_read_phy_reg");
 
+	spin_lock_irqsave(&e1000_phy_lock, flags);
+
 	if ((hw->phy_type == e1000_phy_igp) &&
 	    (reg_addr > MAX_PHY_MULTI_PAGE_REG)) {
 		ret_val = e1000_write_phy_reg_ex(hw, IGP01E1000_PHY_PAGE_SELECT,
 						 (u16) reg_addr);
-		if (ret_val)
+		if (ret_val) {
+			spin_unlock_irqrestore(&e1000_phy_lock, flags);
 			return ret_val;
+		}
 	}
 
 	ret_val = e1000_read_phy_reg_ex(hw, MAX_PHY_REG_ADDRESS & reg_addr,
 					phy_data);
+	spin_unlock_irqrestore(&e1000_phy_lock, flags);
 
 	return ret_val;
 }
@@ -2965,19 +2972,25 @@ static s32 e1000_read_phy_reg_ex(struct e1000_hw *hw, u32 reg_addr,
 s32 e1000_write_phy_reg(struct e1000_hw *hw, u32 reg_addr, u16 phy_data)
 {
 	u32 ret_val;
+	unsigned long flags;
 
 	e_dbg("e1000_write_phy_reg");
 
+	spin_lock_irqsave(&e1000_phy_lock, flags);
+
 	if ((hw->phy_type == e1000_phy_igp) &&
 	    (reg_addr > MAX_PHY_MULTI_PAGE_REG)) {
 		ret_val = e1000_write_phy_reg_ex(hw, IGP01E1000_PHY_PAGE_SELECT,
 						 (u16) reg_addr);
-		if (ret_val)
+		if (ret_val) {
+			spin_unlock_irqrestore(&e1000_phy_lock, flags);
 			return ret_val;
+		}
 	}
 
 	ret_val = e1000_write_phy_reg_ex(hw, MAX_PHY_REG_ADDRESS & reg_addr,
 					 phy_data);
+	spin_unlock_irqrestore(&e1000_phy_lock, flags);
 
 	return ret_val;
 }