Hello ..your smoking
cannabis is not your surgical problem but your dependence on it and you have been smoking it long before your current problem and never been able to quit it.you were never been able to be abstinent more than 2 months and resumed and this time also same thing happens. Every time you must be having one or the other reason to rationalise you relapse and justify your action.
You need to quit not just for surgery but also for your longterm health as may cause many cognitive dysfunction on long term use. You should stop it immediately for surgery because it hamper the action of anaesthetics which may cause you problem during surgery.....what kind of anaesthesia will be required also determine the consequence of your action so don't hide this history from your doctor.
Think about the recommendation and take necessary action