From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754043AbbKBVT1 (ORCPT ); Mon, 2 Nov 2015 16:19:27 -0500 Received: from mail-ig0-f172.google.com ([209.85.213.172]:32914 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752296AbbKBVTX (ORCPT ); Mon, 2 Nov 2015 16:19:23 -0500 MIME-Version: 1.0 In-Reply-To: References: <20151027.233235.1641084823622810663.davem@davemloft.net> <5637C8DF.800@kernel.org> Date: Mon, 2 Nov 2015 13:19:23 -0800 X-Google-Sender-Auth: UC5IcpNR3ACillMUhsbVQ-Poj-E Message-ID: Subject: Re: [GIT] Networking From: Linus Torvalds To: Andy Lutomirski Cc: David Miller , Hannes Frederic Sowa , Andrew Morton , Network Development , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 2, 2015 at 1:16 PM, Linus Torvalds wrote: > On Mon, Nov 2, 2015 at 12:34 PM, Andy Lutomirski wrote: >> >> Getting overflow checking right in more complicated cases is a PITA. > > No it is not. Not for unsigned values. Just to clarify. The "oevrflow" test for unsigned subtracts of "a-b" (it's really an underflow, but whatever) really is just (b > a) Really. That's it. Claiming that that is "complicated" and needs a helper function is not something sane people do. A fifth-grader that isn't good at math can understand that. In contrast, nobody sane understands "usub_overflow(a, b, &res)". So really. Stop making inane arguments. Linus