From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752154AbeEOWqT (ORCPT ); Tue, 15 May 2018 18:46:19 -0400 Received: from mail-pf0-f182.google.com ([209.85.192.182]:44940 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbeEOWqS (ORCPT ); Tue, 15 May 2018 18:46:18 -0400 X-Google-Smtp-Source: AB8JxZqIYC91ohHUhYROA+VN/FSZITpgUN9HXcevcc5fRjkznSahZdw1ERYRd8xIyBWAeDOL0cJFFQ== From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" Subject: [PATCH v7 1/6] softirq: reorder trace_softirqs_on to prevent lockdep splat Date: Tue, 15 May 2018 15:45:54 -0700 Message-Id: <20180515224559.199279-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog In-Reply-To: <20180515224559.199279-1-joel@joelfernandes.org> References: <20180515224559.199279-1-joel@joelfernandes.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm able to reproduce a lockdep splat with config options: CONFIG_PROVE_LOCKING=y, CONFIG_DEBUG_LOCK_ALLOC=y and CONFIG_PREEMPTIRQ_EVENTS=y $ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable --- kernel/softirq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 177de3640c78..8a040bcaa033 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt) { lockdep_assert_irqs_disabled(); + if (preempt_count() == cnt) + trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); + if (softirq_count() == (cnt & SOFTIRQ_MASK)) trace_softirqs_on(_RET_IP_); - preempt_count_sub(cnt); + + __preempt_count_sub(cnt); } /* -- 2.17.0.441.gb46fe60e1d-goog