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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 1E46CC2BB55 for ; Thu, 16 Apr 2020 13:43:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF9C32076D for ; Thu, 16 Apr 2020 13:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044618; bh=58Vk06b0j3aXbBGmy0Io28RxmfmRhNpj7yF6V6krN1w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=L8djlmFs+va/dUYeUcXM6CCGKwTfDNb9jFQKjE1hcGAbNM6WoU1uAifN8vIa17yYf Fv31nBjgLC/La94e73H6/V2PdVrBg6mx+msiugVKscwF2W21tvW7/2NIqxcNfP25Rd /C/trxN1O7wLJ14OTwpHdmHLHxdG6l95sJnAW/8c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730793AbgDPNnd (ORCPT ); Thu, 16 Apr 2020 09:43:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:45014 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2896781AbgDPNdp (ORCPT ); Thu, 16 Apr 2020 09:33:45 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D1D24208E4; Thu, 16 Apr 2020 13:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044025; bh=58Vk06b0j3aXbBGmy0Io28RxmfmRhNpj7yF6V6krN1w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ROn4xqaUrxmxnMOe/hlyVNK4LADNV4Jdwjio7qLylCTBrkw2qju0hCVoqvHXdF6F9 E0EpojJdTDwXCGwGzRc/S39ZFCu8nKk5Fd6iZ5U54SmU7zTQgg2HWAOmXID767R41j O1uZrNx7NqHHd/1Q+WP2fnSUNgmjYK60OSi1bv/s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Ahmed S. Darwish" , Thomas Gleixner , Sasha Levin Subject: [PATCH 5.5 050/257] time/sched_clock: Expire timer in hardirq context Date: Thu, 16 Apr 2020 15:21:41 +0200 Message-Id: <20200416131332.187510103@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200416131325.891903893@linuxfoundation.org> References: <20200416131325.891903893@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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