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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0DEA4C76186 for ; Thu, 25 Jul 2019 02:14:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C04EE22387 for ; Thu, 25 Jul 2019 02:14:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564020891; bh=t6YV1jRiU5k7dKdj12HoNkBQZFF+ujCZGvPs5/A42Kk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=YQYS/CMUdx+HsLn5798DPv+gIgsno517pT9irR2mESc93CNBFNsvwrCNcKudOF+AX zlv1ss2TwyDr1UhDVw35VGJ0rSH2zhXRUrRKcERnhHG1aTHP79PEZGp2pbzG200FWI mfiq7JCwb16QnEtGdJwm5ICpXVuE63/QYYlRTosw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388976AbfGYCOu (ORCPT ); Wed, 24 Jul 2019 22:14:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:57188 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387963AbfGYCOu (ORCPT ); Wed, 24 Jul 2019 22:14:50 -0400 Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 659F721901; Thu, 25 Jul 2019 02:14:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564020889; bh=t6YV1jRiU5k7dKdj12HoNkBQZFF+ujCZGvPs5/A42Kk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=aX2XtK6gB5ejEaBxLqVyJ/TOAcz9MXpO4wFHvJK27BI7nMJ66bC4KQWWx+4KmCJnf 2sfsdssVncyUqYoMZJ/87+BQWYinKi9shQRbhox6E6HbGjOKMzrhqJuCaSeEixWfyO RX+oFOUvxyYHcMi37HkUlskgk2Y07nvAHQdB7lRU= Date: Wed, 24 Jul 2019 19:14:48 -0700 From: Andrew Morton To: Yang Xu Cc: , Subject: Re: [PATCH v2] sys_prctl(): remove unsigned comparision with less than zero Message-Id: <20190724191448.4db70a34f8b89bd8bdc085f5@linux-foundation.org> In-Reply-To: <1563934308-20833-1-git-send-email-xuyang2018.jy@cn.fujitsu.com> References: <20190723094809.GE4832@uranus.lan> <1563934308-20833-1-git-send-email-xuyang2018.jy@cn.fujitsu.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Jul 2019 10:11:48 +0800 Yang Xu wrote: > Currently, when calling prctl(PR_SET_TIMERSLACK, arg2), arg2 is an > unsigned long value, arg2 will never < 0. Negative judgment is > meaningless, so remove it. > > ... > > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -2372,7 +2372,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > error = current->timer_slack_ns; > break; > case PR_SET_TIMERSLACK: > - if (arg2 <= 0) > + if (arg2 == 0) > current->timer_slack_ns = > current->default_timer_slack_ns; A number of years ago Linus expressed approval of such comparisons with unsigned quantities. He felt that it improves readability a little - the reader doesn't have to scroll back and check the type.