i2c: Optimize function i2c_detect()

Check the class flags before allocating the temporary i2c_client
structure, to avoid allocating it when we don't need it.

Also optimize the inner loop a bit.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>

drivers/i2c/i2c-core.c

@@ -1508,26 +1508,25 @@ static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
 	if (!driver->detect || !address_list)
 		return 0;
 
+	/* Stop here if the classes do not match */
+	if (!(adapter->class & driver->class))
+		return 0;
+
 	/* Set up a temporary client to help detect callback */
 	temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 	if (!temp_client)
 		return -ENOMEM;
 	temp_client->adapter = adapter;
 
-	/* Stop here if the classes do not match */
-	if (!(adapter->class & driver->class))
-		goto exit_free;
-
 	for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
 		dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
 			"addr 0x%02x\n", adap_id, address_list[i]);
 		temp_client->addr = address_list[i];
 		err = i2c_detect_address(temp_client, driver);
-		if (err)
-			goto exit_free;
+		if (unlikely(err))
+			break;
 	}
 
- exit_free:
 	kfree(temp_client);
 	return err;
 }