From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8ABF3515892 for ; Mon, 19 Oct 2026 13:11:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415466; cv=none; b=U76TYHgXkZ9xc/bc6EDSgpDUHUdX4xl6o/86OshQHPRsWH7hSbIdbwpb5QSbRMVUy95eSTzERAJRFGuKwsAv/LJ9Bp42CO+FQQ14m6tp2rdkahjN3xb9YAuhs3VaLeosY2eJMbYT4mHLJOitEUZRgZj5IwxZtqd8SzX8DEQ/Hb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415466; c=relaxed/simple; bh=v8NfyFdA+3h3DY0go/ZQ5yMYAIu10GMGqvK5p4nK/mU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=n4ThtHYs5SnBwX2T2jC4voKJHum6ApaVW3zdcQitP1/CYBHQbzbAQmjjNn+auMb6E5gU8OLhG5njx9bk2lgaBH4vF3JpJg8ZvPh+dd4aN6VzV1rQGasQnIBPOD4L2uCpxaXsUuYN3cvY42t53MJDijOknluZ3zzssgZ1vFeWgz4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iA2FxAAu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iA2FxAAu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCC291F000C4; Mon, 19 Oct 2026 13:11:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792415465; bh=K1HI8SEBqjw96bn1RnQ4Y56NBherkmXRP3ao5bzzXGQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iA2FxAAuw/Va9xVA2AugCKdF7xtfNkBPOEppppcOApqcSs5EaxEnGE2Q4ledD8Auq JDrkeyU7gjlwCyOMBzFs6ENhM7TvGIsVWRN2OFmxkYXEP2TvkajVuPhFMsE35IE3OR PG2wnEHArtAJ9SRH59Aql93Kd+vIjxDRwNyz+iP4v3SgfEClwGmqcPJ9LKZk/xEnHF 1LXeRwV0cBj1LeUL5Jl6yvcZGSwP8i3KsJ7su5hEkY5N3LTyD76fu1rVbkI48H2hwr +pBprurY0tYhn8FctBgUhVa4b6VDRkM0BR2Qub+1wQ71FzDuaznTryValWIQwsjMvy xoq6oWziT5/7Q== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Marco Crivellari , Peter Zijlstra , Phil Auld , Thomas Gleixner , Waiman Long Subject: [RFC PATCH 44/49] hrtimer: Move CPUHP_AP_HRTIMERS_DYING post stop_machine() Date: Mon, 19 Oct 2026 15:08:51 +0200 Message-ID: <20261019130856.49711-45-frederic@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261019130856.49711-1-frederic@kernel.org> References: <20261019130856.49711-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes all the teardown callbacks while stopping all CPUs in the system. This doesn't mix-up well with running RT or isolated tasks. In order to transition smoothly from global stop_machine to finer grained synchronization between teardown callbacks and the other CPUs, a new stop machine post function has been introduced to be executed after the main one with IRQs still disabled while other CPUs can exit stop_machine(). The migration of timers can happen while other CPUs are running because everything is serialized with the base locks. Also those locks only nest on the outgoing CPU during hotplug so no locking inversion should happen. Move this teardown callback to post stop_machine() accordingly. Signed-off-by: Frederic Weisbecker --- kernel/cpu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 4b3fcab1575c..1da41620a583 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1275,7 +1275,7 @@ void clear_tasks_mm_cpumask(int cpu) static int take_cpu_down(void *_param) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); - enum cpuhp_state target = max((int)st->target, CPUHP_AP_SMPCFD_DYING); + enum cpuhp_state target = max((int)st->target, CPUHP_AP_HRTIMERS_DYING); int err, cpu = smp_processor_id(); /* Ensure this CPU doesn't handle any more interrupts. */ @@ -1303,7 +1303,7 @@ static int take_cpu_down_post(void *_param) enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); int cpu = smp_processor_id(); - WARN_ON(st->state != CPUHP_AP_SMPCFD_DYING); + WARN_ON(st->state != CPUHP_AP_HRTIMERS_DYING); /* * Invoke the former CPU_DYING callbacks. DYING must not fail! */ -- 2.53.0