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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 3CFAEC3A5A2 for ; Fri, 23 Aug 2019 15:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0FAAB21019 for ; Fri, 23 Aug 2019 15:33:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405589AbfHWPdT (ORCPT ); Fri, 23 Aug 2019 11:33:19 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:35969 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405326AbfHWPdP (ORCPT ); Fri, 23 Aug 2019 11:33:15 -0400 Received: from [5.158.153.52] (helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1i1BYu-0005As-Og; Fri, 23 Aug 2019 17:33:12 +0200 Date: Fri, 23 Aug 2019 17:33:12 +0200 (CEST) From: Thomas Gleixner To: Frederic Weisbecker cc: LKML , Oleg Nesterov , Ingo Molnar , Peter Zijlstra , John Stultz , Anna-Maria Behnsen , Christoph Hellwig Subject: Re: [patch V2 01/38] posix-cpu-timers: Provide task validation functions In-Reply-To: <20190821230319.GD22020@lenoir> Message-ID: References: <20190821190847.665673890@linutronix.de> <20190821192919.326097175@linutronix.de> <20190821223356.GC22020@lenoir> <20190821230319.GD22020@lenoir> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Aug 2019, Frederic Weisbecker wrote: > On Thu, Aug 22, 2019 at 12:33:56AM +0200, Frederic Weisbecker wrote: > > On Wed, Aug 21, 2019 at 09:08:48PM +0200, Thomas Gleixner wrote: > > > The code contains three slightly different copies of validating whether a > > > given clock resolves to a valid task and whether the current caller has > > > permissions to access it. > > > > > > Create central functions. Replace check_clock() as a first step and rename > > > it to something sensible. > > > > > > Signed-off-by: Thomas Gleixner > > > --- > > > kernel/time/posix-cpu-timers.c | 65 +++++++++++++++++++++++++++-------------- > > > 1 file changed, 44 insertions(+), 21 deletions(-) > > > > > > --- a/kernel/time/posix-cpu-timers.c > > > +++ b/kernel/time/posix-cpu-timers.c > > > @@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struc > > > spin_unlock_irq(&task->sighand->siglock); > > > } > > > > > > -static int check_clock(const clockid_t which_clock) > > > +/* > > > + * Functions for validating access to tasks. > > > + */ > > > +static struct task_struct *lookup_task(const pid_t pid, bool thread) > > > { > > > - int error = 0; > > > struct task_struct *p; > > > - const pid_t pid = CPUCLOCK_PID(which_clock); > > > > > > - if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) > > > - return -EINVAL; > > > + if (!pid) > > > + return thread ? current : current->group_leader; > > > > > > - if (pid == 0) > > > - return 0; > > > + p = find_task_by_vpid(pid); > > > + if (!p || p == current) > > > + return p; > > > > What if (p == current && !thread && !has_group_leader_pid(p)) ? > > Ah looking at the next patch, posix_cpu_clock_get_task() and posix_cpu_clock_getres() > had different ad-hoc checks for this specific case. > > clock_getres() used to return -EINVAL while clock_get() doesn't > care. They certainly should agree in their behaviour. I'm not sure which > one is correct. It probably doesn't matter much. Let me stare on the different variants again Thanks, tglx