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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 6A87DC433F5 for ; Fri, 24 Sep 2021 13:04:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E88561269 for ; Fri, 24 Sep 2021 13:04:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346429AbhIXNG1 (ORCPT ); Fri, 24 Sep 2021 09:06:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:34548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345905AbhIXNE1 (ORCPT ); Fri, 24 Sep 2021 09:04:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5EDD561268; Fri, 24 Sep 2021 12:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632488130; bh=KoRok/c289mOUfiuFf5DqIQBpPD/AVRD0esmWN417rY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Oriu9PrT8f2EAgXjgNfa71/dUj6pPEL1i3mbx1cy0i09aUWPzUZNlduvfbp53DBrP WyNzkZ01DBVRzTds8wSer9fyWEa41/I2DB8EV48mfHoIj/wglJsmkG9xqFjkIdtq/t 8NiO8+u5lRGcLAVaesuj3aphe8+ZxBqGUGw6cOrc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Sebastian Andrzej Siewior , Sasha Levin Subject: [PATCH 5.14 096/100] sched/idle: Make the idle timer expire in hard interrupt context Date: Fri, 24 Sep 2021 14:44:45 +0200 Message-Id: <20210924124344.695410214@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210924124341.214446495@linuxfoundation.org> References: <20210924124341.214446495@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sebastian Andrzej Siewior [ Upstream commit 9848417926353daa59d2b05eb26e185063dbac6e ] The intel powerclamp driver will setup a per-CPU worker with RT priority. The worker will then invoke play_idle() in which it remains in the idle poll loop until it is stopped by the timer it started earlier. That timer needs to expire in hard interrupt context on PREEMPT_RT. Otherwise the timer will expire in ksoftirqd as a SOFT timer but that task won't be scheduled on the CPU because its priority is lower than the priority of the worker which is in the idle loop. Always expire the idle timer in hard interrupt context. Reported-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210906113034.jgfxrjdvxnjqgtmc@linutronix.de Signed-off-by: Sasha Levin --- kernel/sched/idle.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 912b47aa99d8..d17b0a5ce6ac 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -379,10 +379,10 @@ void play_idle_precise(u64 duration_ns, u64 latency_ns) cpuidle_use_deepest_state(latency_ns); it.done = 0; - hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); it.timer.function = idle_inject_timer_fn; hrtimer_start(&it.timer, ns_to_ktime(duration_ns), - HRTIMER_MODE_REL_PINNED); + HRTIMER_MODE_REL_PINNED_HARD); while (!READ_ONCE(it.done)) do_idle(); -- 2.33.0