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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 72C11C43381 for ; Thu, 11 Mar 2021 12:38:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1ED9064FF9 for ; Thu, 11 Mar 2021 12:38:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233179AbhCKMhd (ORCPT ); Thu, 11 Mar 2021 07:37:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:59706 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233190AbhCKMhR (ORCPT ); Thu, 11 Mar 2021 07:37:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1794064FE6; Thu, 11 Mar 2021 12:37:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615466237; bh=I4y2AElfIxluZFcgYq0yvzhKqir2bW0RPqelVOJJZ0Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=es5hNvnPZVV/ROxHIEBT0u9HtS4yhm0nUd/voR747OBTeM9uIkNm0C3Dkd8WyQV+/ ifgmnR9eQaqD0CtaNDMsHIEtTataXgYm6MpA5E+uAdL/ILtQDwystlPujSJaiVJiU7 Xo3sGkTPpQtCNBCSb8mpF01OjrprfJ7xTmywx0gg0QRB3D/VjUKg8r2WxZkqQonVRL n+GXcxnWaumPbLKnwfCdBsj49WuURlOLNGd7fZfQ+BgMnSRYoM/kQ3KGCJMPZr7U3N NLdPC825j5uWGPLgv3eaeB+NRCuLpzjCb6znQcXrQaO+MQYmSPZozcld4VLsRnncF4 H5dUH2rpzJ4vg== From: Frederic Weisbecker To: Peter Zijlstra , Thomas Gleixner Cc: LKML , "Zhou Ti (x2019cwm)" , "Rafael J . Wysocki" , Yunfeng Ye , Frederic Weisbecker , "Paul E . McKenney" , Marcelo Tosatti , Ingo Molnar Subject: [PATCH 01/10] tick/nohz: Prevent tick_nohz_get_sleep_length() from returning negative value Date: Thu, 11 Mar 2021 13:36:59 +0100 Message-Id: <20210311123708.23501-2-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210311123708.23501-1-frederic@kernel.org> References: <20210311123708.23501-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Zhou Ti (x2019cwm)" If the hardware clock happens to fire its interrupts late, two possible issues can happen while calling tick_nohz_get_sleep_length(). Either: 1) The next clockevent device event is due past the last idle entry time. or: 2) The last timekeeping update happened before the last idle entry time and the next timer callback expires before the last idle entry time. Make sure that both cases are handled to avoid returning a negative duration to the cpuidle governors. Signed-off-by: Ti Zhou Cc: Rafael J. Wysocki Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Frederic Weisbecker --- kernel/time/tick-sched.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index e10a4af88737..22b6a46818cf 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1142,6 +1142,9 @@ ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) *delta_next = ktime_sub(dev->next_event, now); + if (unlikely(*delta_next < 0)) + *delta_next = 0; + if (!can_stop_idle_tick(cpu, ts)) return *delta_next; @@ -1156,6 +1159,9 @@ ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) next_event = min_t(u64, next_event, hrtimer_next_event_without(&ts->sched_timer)); + if (unlikely(next_event < now)) + next_event = now; + return ktime_sub(next_event, now); } -- 2.25.1