Is updating with inline select atomic in mysql? - mysql

Question

I have an app that calculates points for a user, based on certain rules, for every dollar they spent on my portal. I am using the following stored procedure to update the points of the user:
DROP PROCEDURE IF EXISTS `Update_Points`;
DELIMITER $$
CREATE PROCEDURE `Update_Points` (
pUserId BIGINT,
pPoints DECIMAL(13,2), // points accrued for the amount 'pAmount'
pAmount DECIMAL(13,2) // amount spent by the user
)
SPROC:BEGIN
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
RESIGNAL;
END;
START TRANSACTION;
INSERT INTO AuditTable(UserId, Amount, Points)
VALUES (pUserId, pAmount, pPoints);
UPDATE PlayerPoints
SET Points = Points + pPoints
WHERE UserId = pUserId;
SELECT ROW_COUNT() INTO #RowsUpdated;
COMMIT;
SELECT #RowsUpdated;
END$$
DELIMITER ;
I am seeing discrepancies in total points accrued by some of the users. I know this because we have another backend database that stores user transactions.
We have multiple instances of our applications running to handle the load so one idea was that it could this stored procedure that could cause the accrued points discrepancy, based on the idea that the following snippet might not be atomic
UPDATE PlayerPoints
SET Points = Points + pPoints
WHERE UserId = pUserId;
So my question to you gurus of mysql is whether the above UPDATE statement is atomic or not?
The PlayerPoints table has following structure:
UserId
Amount
Points
1
30
50
1
10
20
2
35
30
3
10
20
2
35
30