How to call stored procedure inside trigger?
Instead of creating trigger you can use below code, It will also return you success or failure message.

DELIMITER ;
DROP FUNCTION IF EXISTS to_updatequantity;

DELIMITER //
CREATE FUNCTION to_updatequantity(id int, qty int) RETURNS CHAR(100) DETERMINISTIC
BEGIN

    SELECT prod_qty INTO @var_prod_qty FROM product_master WHERE prod_id = id;

    IF (@var_prod_qty &gt; qty) THEN
        UPDATE product_master SET prod_qty = prod_qty - qty WHERE prod_id = id;
        SET @msg = 'prod_qty is updated successfully';
    ELSE 
        SET @msg = 'prod_qty is less than or equal to ordered qty'; 
    END IF;  

RETURN @msg;
END //
DELIMITER ;