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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 975D4C64EB8 for ; Tue, 2 Oct 2018 20:20:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60C9720684 for ; Tue, 2 Oct 2018 20:20:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 60C9720684 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S1727625AbeJCDFs (ORCPT ); Tue, 2 Oct 2018 23:05:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2678 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726194AbeJCDFr (ORCPT ); Tue, 2 Oct 2018 23:05:47 -0400 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7386488304; Tue, 2 Oct 2018 20:20:42 +0000 (UTC) Received: from llong.com (dhcp-17-55.bos.redhat.com [10.18.17.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id CCE7C308BDA0; Tue, 2 Oct 2018 20:20:41 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon Cc: linux-kernel@vger.kernel.org, Waiman Long Subject: [PATCH v2 2/5] locking/lockdep: Eliminate redundant irqs check in __lock_acquire() Date: Tue, 2 Oct 2018 16:19:17 -0400 Message-Id: <1538511560-10090-3-git-send-email-longman@redhat.com> In-Reply-To: <1538511560-10090-1-git-send-email-longman@redhat.com> References: <1538511560-10090-1-git-send-email-longman@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 02 Oct 2018 20:20:42 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The static __lock_acquire() function has only two callers: 1) lock_acquire() 2) reacquire_held_locks() In lock_acquire(), raw_local_irq_save() is called beforehand. So IRQs must have been disabled. So the check DEBUG_LOCKS_WARN_ON(!irqs_disabled()) is kind of redundant in this case. So move the above check to reacquire_held_locks() to eliminate redundant code in the lock_acquire() path. Signed-off-by: Waiman Long --- kernel/locking/lockdep.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 8f9de7cd11ab..bd59163b0550 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3192,6 +3192,10 @@ static int __lock_is_held(const struct lockdep_map *lock, int read); /* * This gets called for every mutex_lock*()/spin_lock*() operation. * We maintain the dependency maps and validate the locking attempt: + * + * The callers must make sure that IRQs are disabled before calling it, + * otherwise we could get an interrupt which would want to take locks, + * which would end up in lockdep again. */ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, int trylock, int read, int check, int hardirqs_off, @@ -3209,14 +3213,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (unlikely(!debug_locks)) return 0; - /* - * Lockdep should run with IRQs disabled, otherwise we could - * get an interrupt which would want to take locks, which would - * end up in lockdep and have you got a head-ache already? - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return 0; - if (!prove_locking || lock->key == &__lockdep_no_validate__) check = 0; @@ -3473,6 +3469,9 @@ static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, { struct held_lock *hlock; + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return 0; + for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { if (!__lock_acquire(hlock->instance, hlock_class(hlock)->subclass, -- 2.18.0