I agree you should be civil about it. But, if it is objectionable to you, you should let your neighbors know politely. I bet they would have no problem taking a walk or smoking it out front.

For Pete's sake, a joint is finished in 5 minutes and people don't chain smoke like they do cigarettes. If you think that 5 minutes of subjectively foul odor requires new bylaws, then you are out to lunch.