linux-kernel - [PATCH v7 1/6] softirq: reorder trace_softirqs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180515224559.199279-2-joel@joelfernandes.org>
Date:   Tue, 15 May 2018 15:45:54 -0700
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: [PATCH v7 1/6] softirq: reorder trace_softirqs_on to prevent lockdep splat

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