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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 17B0BC04ABB for ; Tue, 11 Sep 2018 18:04:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDFC42086A for ; Tue, 11 Sep 2018 18:04:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BDFC42086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727650AbeIKXEi (ORCPT ); Tue, 11 Sep 2018 19:04:38 -0400 Received: from terminus.zytor.com ([198.137.202.136]:44005 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726622AbeIKXEi (ORCPT ); Tue, 11 Sep 2018 19:04:38 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w8BI3oQb2330617 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 11 Sep 2018 11:03:50 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w8BI3oYh2330614; Tue, 11 Sep 2018 11:03:50 -0700 Date: Tue, 11 Sep 2018 11:03:50 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Peter Zijlstra Message-ID: Cc: torvalds@linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, mingo@kernel.org Reply-To: peterz@infradead.org, mingo@kernel.org, torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org In-Reply-To: <20180911095127.GT24082@hirez.programming.kicks-ass.net> References: <20180911095127.GT24082@hirez.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/lockdep, cpu/hotplug: Annotate AP thread Git-Commit-ID: cb92173d1f0474784c6171a9d3fdbbca0ee53554 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: cb92173d1f0474784c6171a9d3fdbbca0ee53554 Gitweb: https://git.kernel.org/tip/cb92173d1f0474784c6171a9d3fdbbca0ee53554 Author: Peter Zijlstra AuthorDate: Tue, 11 Sep 2018 11:51:27 +0200 Committer: Ingo Molnar CommitDate: Tue, 11 Sep 2018 20:01:03 +0200 locking/lockdep, cpu/hotplug: Annotate AP thread Anybody trying to assert the cpu_hotplug_lock is held (lockdep_assert_cpus_held()) from AP callbacks will fail, because the lock is held by the BP. Stick in an explicit annotation in cpuhp_thread_fun() to make this work. Reported-by: Ingo Molnar Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-tip-commits@vger.kernel.org Fixes: cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations") Link: http://lkml.kernel.org/r/20180911095127.GT24082@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/cpu.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index 0097acec1c71..be4859f07153 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -315,6 +315,16 @@ void lockdep_assert_cpus_held(void) percpu_rwsem_assert_held(&cpu_hotplug_lock); } +static void lockdep_acquire_cpus_lock(void) +{ + rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_); +} + +static void lockdep_release_cpus_lock(void) +{ + rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_); +} + /* * Wait for currently running CPU hotplug operations to complete (if any) and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects @@ -344,6 +354,17 @@ void cpu_hotplug_enable(void) cpu_maps_update_done(); } EXPORT_SYMBOL_GPL(cpu_hotplug_enable); + +#else + +static void lockdep_acquire_cpus_lock(void) +{ +} + +static void lockdep_release_cpus_lock(void) +{ +} + #endif /* CONFIG_HOTPLUG_CPU */ #ifdef CONFIG_HOTPLUG_SMT @@ -616,6 +637,12 @@ static void cpuhp_thread_fun(unsigned int cpu) */ smp_mb(); + /* + * The BP holds the hotplug lock, but we're now running on the AP, + * ensure that anybody asserting the lock is held, will actually find + * it so. + */ + lockdep_acquire_cpus_lock(); cpuhp_lock_acquire(bringup); if (st->single) { @@ -661,6 +688,7 @@ static void cpuhp_thread_fun(unsigned int cpu) } cpuhp_lock_release(bringup); + lockdep_release_cpus_lock(); if (!st->should_run) complete_ap_thread(st, bringup);