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=-3.8 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 7FB05C32750 for ; Tue, 30 Jul 2019 22:41:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F171206A2 for ; Tue, 30 Jul 2019 22:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388311AbfG3Wk7 (ORCPT ); Tue, 30 Jul 2019 18:40:59 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:58711 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388261AbfG3Wk5 (ORCPT ); Tue, 30 Jul 2019 18:40:57 -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 1hsanU-0002O3-5F; Wed, 31 Jul 2019 00:40:44 +0200 Message-Id: <20190730223828.690771827@linutronix.de> User-Agent: quilt/0.65 Date: Wed, 31 Jul 2019 00:33:51 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Sebastian Siewior , Anna-Maria Gleixner , Steven Rostedt , Julia Cartwright Subject: [patch 3/7] itimers: Prepare for PREEMPT_RT References: <20190730223348.409366334@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 Use the hrtimer_cancel_wait_running() synchronization mechanism to prevent priority inversion and live locks on PREEMPT_RT. As a benefit the retry loop gains the missing cpu_relax() on !RT. [ tglx: Split out of combo patch ] Signed-off-by: Anna-Maria Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner --- kernel/time/itimer.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/time/itimer.c +++ b/kernel/time/itimer.c @@ -213,6 +213,7 @@ int do_setitimer(int which, struct itime /* We are sharing ->siglock with it_real_fn() */ if (hrtimer_try_to_cancel(timer) < 0) { spin_unlock_irq(&tsk->sighand->siglock); + hrtimer_cancel_wait_running(timer); goto again; } expires = timeval_to_ktime(value->it_value);