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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 C5921C2BBFD for ; Fri, 10 Apr 2020 03:59:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C32520936 for ; Fri, 10 Apr 2020 03:59:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586491155; bh=gXuLcjnFmu7I8/9QP80Zfyjgrdu24JxyI56rH78YD5M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0cQhp0awp321A2mpPyx+/WADEJW7ElMQ6VbAyN9f7sjY6k6AvhoTr02wxf9dzS6XK YY/zPJpqQ38Jxz/RPK5bLLN4qATDeHDOlA02R0ZLRw+YVSDIV3tV/FWoevfGyZqr0j Rf3T+Av0rPMT1nXIML2M8Yd2RIQPqGhEFCvuSfPo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728189AbgDJDsa (ORCPT ); Thu, 9 Apr 2020 23:48:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:60066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728164AbgDJDsa (ORCPT ); Thu, 9 Apr 2020 23:48:30 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 1974E2137B; Fri, 10 Apr 2020 03:48:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586490509; bh=gXuLcjnFmu7I8/9QP80Zfyjgrdu24JxyI56rH78YD5M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mXBwtyOL2zdfdPRXNTjBlLpE/sAt3tsLacLBorUu9Ta3fjvB10J74HCOIFfTlegwG 5y3myp6f2nUB+MN0ohwNhmBWmIS9rD+9VhpHZUrfQTeVco73J49zlT6k2SWYj1M5qZ +nL6ePrD7hvXDzrpYO97UTxt570d39I44JtgOg2c= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Ahmed S. Darwish" , Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 5.5 24/56] time/sched_clock: Expire timer in hardirq context Date: Thu, 9 Apr 2020 23:47:28 -0400 Message-Id: <20200410034800.8381-24-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200410034800.8381-1-sashal@kernel.org> References: <20200410034800.8381-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Ahmed S. Darwish" [ Upstream commit 2c8bd58812ee3dbf0d78b566822f7eacd34bdd7b ] To minimize latency, PREEMPT_RT kernels expires hrtimers in preemptible softirq context by default. This can be overriden by marking the timer's expiry with HRTIMER_MODE_HARD. sched_clock_timer is missing this annotation: if its callback is preempted and the duration of the preemption exceeds the wrap around time of the underlying clocksource, sched clock will get out of sync. Mark the sched_clock_timer for expiry in hard interrupt context. Signed-off-by: Ahmed S. Darwish Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200309181529.26558-1-a.darwish@linutronix.de Signed-off-by: Sasha Levin --- kernel/time/sched_clock.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index dbd69052eaa66..a5538dd76a819 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -207,7 +207,8 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) if (sched_clock_timer.function != NULL) { /* update timeout for clock wrap */ - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, + HRTIMER_MODE_REL_HARD); } r = rate; @@ -251,9 +252,9 @@ void __init generic_sched_clock_init(void) * Start the timer to keep sched_clock() properly updated and * sets the initial epoch. */ - hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); sched_clock_timer.function = sched_clock_poll; - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD); } /* @@ -290,7 +291,7 @@ void sched_clock_resume(void) struct clock_read_data *rd = &cd.read_data[0]; rd->epoch_cyc = cd.actual_read_sched_clock(); - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD); rd->read_sched_clock = cd.actual_read_sched_clock; } -- 2.20.1