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 DFDDDC3A5A0 for ; Mon, 19 Aug 2019 15:48:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BEE0422CE5 for ; Mon, 19 Aug 2019 15:48:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728302AbfHSPs2 (ORCPT ); Mon, 19 Aug 2019 11:48:28 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:47589 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727824AbfHSPpm (ORCPT ); Mon, 19 Aug 2019 11:45:42 -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 1hzjql-0006uf-TG; Mon, 19 Aug 2019 17:45:39 +0200 Message-Id: <20190819143802.423098617@linutronix.de> User-Agent: quilt/0.65 Date: Mon, 19 Aug 2019 16:31:52 +0200 From: Thomas Gleixner To: LKML Cc: Oleg Nesterov , Ingo Molnar , Peter Zijlstra , John Stultz , Frederic Weisbecker , Anna-Maria Behnsen Subject: [patch 11/44] posix-cpu-timers: Provide quick sample function for itimer References: <20190819143141.221906747@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 get_itimer() needs a sample of the current thread group cputime. It invokes thread_group_cputimer() - which is a misnomer. That function also starts eventually the group cputime accouting which is bogus because the accounting is already active when a timer is armed. Signed-off-by: Thomas Gleixner --- include/linux/sched/cputime.h | 2 +- kernel/time/posix-cpu-timers.c | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+), 1 deletion(-) --- a/include/linux/sched/cputime.h +++ b/include/linux/sched/cputime.h @@ -62,7 +62,7 @@ extern void cputime_adjust(struct task_c */ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times); void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times); - +void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times); /* * The following are functions that support scheduler-internal time accounting. --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -232,6 +232,27 @@ static inline void sample_cputime_atomic times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime); } +/** + * thread_group_sample_cputime - Sample cputime for a given task + * @tsk: Task for which cputime needs to be started + * @iimes: Storage for time samples + * + * Called from sys_getitimer() to calculate the expiry time of an active + * timer. That means group cputime accounting is already active. Called + * with task sighand lock held. + * + * Updates @times with an uptodate sample of the thread group cputimes. + */ +void thread_group_sample_cputime(struct task_struct *tsk, + struct task_cputime *times) +{ + struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; + + WARN_ON_ONCE(!cputimer->running); + + sample_cputime_atomic(times, &cputimer->cputime_atomic); +} + void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) { struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;