From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0DC1C433DF for ; Wed, 20 May 2020 16:08:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E115206F1 for ; Wed, 20 May 2020 16:08:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="xbrxSUuT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726946AbgETQIv (ORCPT ); Wed, 20 May 2020 12:08:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726650AbgETQIv (ORCPT ); Wed, 20 May 2020 12:08:51 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F22CEC061A0E for ; Wed, 20 May 2020 09:08:50 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id j5so3761572wrq.2 for ; Wed, 20 May 2020 09:08:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=b0xYWh+w/F4qTSH0QTclL7MS2e+5mKVzQgF0NwX1VdA=; b=xbrxSUuTV4VsNXGHpyNiBREQh4CjaWtB9BN3dY9RtRsbQ3q6Wc1c9zuirNc4ZD5/nT Na+uOjpDr1J/5SJkZVH7w3a/7jxWGFfeFYXRkQlbsJuSC+swTEBM7Mihk9eJ9vk8eE1F rmg5VkyVcsfs5z09UB0WfHUjghVCddAtVvIF73rqjLcOJB0vkmJ/hNqUIM5K9bHYtYB2 Qk4fB9WSOL3xDfNiYR6N7lAnv/yv1Jpgq+z/7mRt5cEmMc9CjeaaX+kHeO8sPiXuI/BX XKbg13F2pI5vgTw1ZgCCUDSxyFh3ptYp3UEMYTYaVhykHgrjuTAfikxoac2kbplmLjth OYDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=b0xYWh+w/F4qTSH0QTclL7MS2e+5mKVzQgF0NwX1VdA=; b=Kdc8jqbsv0+yqtN5UaPWHIxXb53lFuoIHQfZrAahf7tEVNy4VLnE46B3OVvCSkdNfj HGscsKdo9Y7kb+OJce65NjwG4JKnkiI53bVyCGwA2OnpArRnyvooRrvtXGxyzeyXHOsU CZOdmSO1pjzultxOu2vRI/oq0LVzJyhzIlYcK5gbcbQ3T2rfq1jzsKLPLZgUTKQYDnc/ zQ1bie+ehwswf+QFVZajb0bPnnfyf1c64dOvEDhk22U00M8GnyHnFNYwLlYi6yxPVCeQ OuyIfyYMCSvkufbEMdkNfQDyYubbCowdT1BcQst5iP55/rfCIuXoLsTZUybYAPmLGI2E 6Ctw== X-Gm-Message-State: AOAM533QhFGDo+cBUoj5Ts82InEeoIa7Z7E01LWb4sKMaecYLweJgri6 o6CGIs2SaZctl4mqzToYv4hQzQ== X-Google-Smtp-Source: ABdhPJz93P3tc5SPc/AYro69bXA2d3D8ewi0B2Ij2Ds+zzrwsQ5omOgXlzrtQVfEBTM0udRUP66uEQ== X-Received: by 2002:a5d:5751:: with SMTP id q17mr4842701wrw.106.1589990929733; Wed, 20 May 2020 09:08:49 -0700 (PDT) Received: from holly.lan (cpc141214-aztw34-2-0-cust773.18-1.cable.virginm.net. [86.9.19.6]) by smtp.gmail.com with ESMTPSA id z11sm3297731wro.48.2020.05.20.09.08.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2020 09:08:49 -0700 (PDT) Date: Wed, 20 May 2020 17:08:47 +0100 From: Daniel Thompson To: Douglas Anderson Cc: Jason Wessel , sumit.garg@linaro.org, Chuhong Yuan , Dan Carpenter , Masahiro Yamada , kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kdb: Cleanup math with KDB_CMD_HISTORY_COUNT Message-ID: <20200520160847.dpvut45zjd5msz6w@holly.lan> References: <20200507161125.1.I2cce9ac66e141230c3644b8174b6c15d4e769232@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200507161125.1.I2cce9ac66e141230c3644b8174b6c15d4e769232@changeid> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 07, 2020 at 04:11:46PM -0700, Douglas Anderson wrote: > From code inspection the math in handle_ctrl_cmd() looks super sketchy > because it subjects -1 from cmdptr and then does a "% > KDB_CMD_HISTORY_COUNT". It turns out that this code works because > "cmdptr" is unsigned and KDB_CMD_HISTORY_COUNT is a nice power of 2. > Let's make this a little less sketchy. > > This patch should be a no-op. > > Signed-off-by: Douglas Anderson Applied, thanks!