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=-3.7 required=3.0 tests=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 A795AC04EBF for ; Mon, 23 Sep 2019 14:57:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CDE220578 for ; Mon, 23 Sep 2019 14:57:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731563AbfIWO5B (ORCPT ); Mon, 23 Sep 2019 10:57:01 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:58810 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731270AbfIWO4s (ORCPT ); Mon, 23 Sep 2019 10:56:48 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1iCPle-0007ae-Mn; Mon, 23 Sep 2019 16:56:46 +0200 Message-Id: <20190923145528.764987925@linutronix.de> User-Agent: quilt/0.65 Date: Mon, 23 Sep 2019 16:54:39 +0200 From: Thomas Gleixner To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Ingo Molnar , Oleg Nesterov , Michael Kerrisk , Kees Cook , Frederic Weisbecker Subject: [patch V2 4/6] posix-cpu-timers: Make PID=0 and PID=self handling consistent References: <20190923145435.507024424@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner If the PID encoded into the clock id is 0 then the target is either the calling thread itself or the process to which it belongs. If the current thread encodes its own PID on a process wide clock then there is no reason not to treat it in the same way as the PID=0 case. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker --- V2: Remove the extra same_thread_group() check which is pointless. --- kernel/time/posix-cpu-timers.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -90,18 +90,20 @@ static struct task_struct *lookup_task(c } else { /* + * Timer is going to be attached to a process. If p is + * current then treat it like the PID=0 case above. + * This also avoids the ptrace overhead. + */ + if (p == current) + return current->group_leader; + + /* * Process wide timers need the group leader because they * take a reference on it and store the task pointer until * the timer is destroyed. */ if (!has_group_leader_pid(p)) return NULL; - - /* - * Avoid the ptrace overhead when this is current's process - */ - if (same_thread_group(p, current)) - return p; } /* Decide based on the ptrace permissions. */