A double negative consists of two negative words used in the same expression. Most double negatives are nonstandard English and should not be used in writing.
I haven't got none (any).
Or
I have none
Barely, hardly, and scarcely are already negative and do not need to be reinforced.
I don't hardly ever have time to read these days.
Two negatives are acceptable only if they are used to suggest the gray area of meaning between negative and positive.
Joshua is not unfriendly, [meaning that he is neither hostile nor friendly]
It is not without regret that I offer my resignation, [implying mixed feelings rather than only regret]