igb: Fix for lockdep issue in igb_get_i2c_client

This patch fixes a lockdep warning in igb_get_i2c_client by
refactoring the initialization and usage of the i2c_client
completely.  There is no on the fly allocation of the single
client needed today.
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/igb.h

@@ -447,7 +447,7 @@ struct igb_adapter {
 #endif
 	struct i2c_algo_bit_data i2c_algo;
 	struct i2c_adapter i2c_adap;
-	struct igb_i2c_client_list *i2c_clients;
+	struct i2c_client *i2c_client;
 };
 
 #define IGB_FLAG_HAS_MSI		(1 << 0)

drivers/net/ethernet/intel/igb/igb_hwmon.c

@@ -39,6 +39,10 @@
 #include <linux/pci.h>
 
 #ifdef CONFIG_IGB_HWMON
+struct i2c_board_info i350_sensor_info = {
+	I2C_BOARD_INFO("i350bb", (0Xf8 >> 1)),
+};
+
 /* hwmon callback functions */
 static ssize_t igb_hwmon_show_location(struct device *dev,
 					 struct device_attribute *attr,
@@ -188,6 +192,7 @@ int igb_sysfs_init(struct igb_adapter *adapter)
 	unsigned int i;
 	int n_attrs;
 	int rc = 0;
+	struct i2c_client *client = NULL;
 
 	/* If this method isn't defined we don't support thermals */
 	if (adapter->hw.mac.ops.init_thermal_sensor_thresh == NULL)
@@ -198,6 +203,15 @@ int igb_sysfs_init(struct igb_adapter *adapter)
 		if (rc)
 			goto exit;
 
+	/* init i2c_client */
+	client = i2c_new_device(&adapter->i2c_adap, &i350_sensor_info);
+	if (client == NULL) {
+		dev_info(&adapter->pdev->dev,
+			"Failed to create new i2c device..\n");
+		goto exit;
+	}
+	adapter->i2c_client = client;
+
 	/* Allocation space for max attributes
 	 * max num sensors * values (loc, temp, max, caution)
 	 */

drivers/net/ethernet/intel/igb/igb_main.c

@@ -1923,10 +1923,6 @@ void igb_set_fw_version(struct igb_adapter *adapter)
 	return;
 }
 
-static const struct i2c_board_info i350_sensor_info = {
-	I2C_BOARD_INFO("i350bb", 0Xf8),
-};
-
 /*  igb_init_i2c - Init I2C interface
  *  @adapter: pointer to adapter structure
  *
@@ -7717,67 +7713,6 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba)
 	}
 }
 
-static DEFINE_SPINLOCK(i2c_clients_lock);
-
-/*  igb_get_i2c_client - returns matching client
- *  in adapters's client list.
- *  @adapter: adapter struct
- *  @dev_addr: device address of i2c needed.
- */
-static struct i2c_client *
-igb_get_i2c_client(struct igb_adapter *adapter, u8 dev_addr)
-{
-	ulong flags;
-	struct igb_i2c_client_list *client_list;
-	struct i2c_client *client = NULL;
-	struct i2c_board_info client_info = {
-		I2C_BOARD_INFO("igb", 0x00),
-	};
-
-	spin_lock_irqsave(&i2c_clients_lock, flags);
-	client_list = adapter->i2c_clients;
-
-	/* See if we already have an i2c_client */
-	while (client_list) {
-		if (client_list->client->addr == (dev_addr >> 1)) {
-			client = client_list->client;
-			goto exit;
-		} else {
-			client_list = client_list->next;
-		}
-	}
-
-	/* no client_list found, create a new one */
-	client_list = kzalloc(sizeof(*client_list), GFP_ATOMIC);
-	if (client_list == NULL)
-		goto exit;
-
-	/* dev_addr passed to us is left-shifted by 1 bit
-	 * i2c_new_device call expects it to be flush to the right.
-	 */
-	client_info.addr = dev_addr >> 1;
-	client_info.platform_data = adapter;
-	client_list->client = i2c_new_device(&adapter->i2c_adap, &client_info);
-	if (client_list->client == NULL) {
-		dev_info(&adapter->pdev->dev,
-			"Failed to create new i2c device..\n");
-		goto err_no_client;
-	}
-
-	/* insert new client at head of list */
-	client_list->next = adapter->i2c_clients;
-	adapter->i2c_clients = client_list;
-
-	client = client_list->client;
-	goto exit;
-
-err_no_client:
-	kfree(client_list);
-exit:
-	spin_unlock_irqrestore(&i2c_clients_lock, flags);
-	return client;
-}
-
 /*  igb_read_i2c_byte - Reads 8 bit word over I2C
  *  @hw: pointer to hardware structure
  *  @byte_offset: byte offset to read
@@ -7791,7 +7726,7 @@ s32 igb_read_i2c_byte(struct e1000_hw *hw, u8 byte_offset,
 				u8 dev_addr, u8 *data)
 {
 	struct igb_adapter *adapter = container_of(hw, struct igb_adapter, hw);
-	struct i2c_client *this_client = igb_get_i2c_client(adapter, dev_addr);
+	struct i2c_client *this_client = adapter->i2c_client;
 	s32 status;
 	u16 swfw_mask = 0;
 
@@ -7828,7 +7763,7 @@ s32 igb_write_i2c_byte(struct e1000_hw *hw, u8 byte_offset,
 				 u8 dev_addr, u8 data)
 {
 	struct igb_adapter *adapter = container_of(hw, struct igb_adapter, hw);
-	struct i2c_client *this_client = igb_get_i2c_client(adapter, dev_addr);
+	struct i2c_client *this_client = adapter->i2c_client;
 	s32 status;
 	u16 swfw_mask = E1000_SWFW_PHY0_SM;