Hi folks, This is a resend of a patch from months ago that can be found here: https://lore.kernel.org/linux-xfs/20191121004437.9633-1-david@xxxxxxxxxxxxx/ I've split it into two patches and cleaned it up further and retested it, and all is good now. Essentially it solves the problem of production systems taking percpu_counter_sum() overhead in a hot path when the sum is only used for debug purposes and not actually compiled in to production kernels. As a further cleanup of this code, the error handling never returns errors at all to the caller, so it's only for debug purposes. Given that the error handling logic is wrong and we throw it away on debug kernels anyway, just get rid of all of it. Cheers, Dave.
