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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 A6448C43142 for ; Thu, 2 Aug 2018 22:26:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EDFF215EA for ; Thu, 2 Aug 2018 22:26:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5EDFF215EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732074AbeHCATh (ORCPT ); Thu, 2 Aug 2018 20:19:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:34820 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbeHCATh (ORCPT ); Thu, 2 Aug 2018 20:19:37 -0400 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 977B7215E4; Thu, 2 Aug 2018 22:26:25 +0000 (UTC) From: Tom Zanussi To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: rostedt@goodmis.org, tglx@linutronix.de, C.Emde@osadl.org, jkacur@redhat.com, bigeasy@linutronix.de, daniel.wagner@siemens.com, julia@ni.com, stable-rt@vger.kernel.org, Daniel Wagner , Tom Zanussi Subject: [PATCH 03/15] posix-timers: move the rcu head out of the union Date: Thu, 2 Aug 2018 17:25:18 -0500 Message-Id: X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior On RT the timer can be preempted while running and therefore we wait with timer_wait_for_callback() for the timer to complete (instead of busy looping). The RCU-readlock is held to ensure that this posix timer is not removed while we wait on it. If the timer is removed then it invokes call_rcu() with a pointer that is shared with the hrtimer because it is part of the same union. In order to avoid any possible side effects I am moving the rcu pointer out of the union. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Daniel Wagner (cherry picked from commit 57f93c5f597fa32af860321c5bca34bc5ffe08e1) Signed-off-by: Tom Zanussi --- include/linux/posix-timers.h | 2 +- kernel/time/posix-timers.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index 907f3fd191ac..e2e43c61f6a1 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -92,8 +92,8 @@ struct k_itimer { struct alarm alarmtimer; ktime_t interval; } alarm; - struct rcu_head rcu; } it; + struct rcu_head rcu; }; struct k_clock { diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index b5e0ff549422..bdf91054e6c3 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -560,7 +560,7 @@ static struct k_itimer * alloc_posix_timer(void) static void k_itimer_rcu_free(struct rcu_head *head) { - struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu); + struct k_itimer *tmr = container_of(head, struct k_itimer, rcu); kmem_cache_free(posix_timers_cache, tmr); } @@ -577,7 +577,7 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) } put_pid(tmr->it_pid); sigqueue_free(tmr->sigq); - call_rcu(&tmr->it.rcu, k_itimer_rcu_free); + call_rcu(&tmr->rcu, k_itimer_rcu_free); } static struct k_clock *clockid_to_kclock(const clockid_t id) -- 2.14.1