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From: "tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: locking/urgent] lockdep: Fix nr_unused_locks accounting
Date: Sat, 31 Oct 2020 11:30:31 -0000	[thread overview]
Message-ID: <160414383158.397.3025016969633820018.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20201027124834.GL2628@hirez.programming.kicks-ass.net>

The following commit has been merged into the locking/urgent branch of tip:

Commit-ID:     1a39340865ce505a029b37aeb47a3e4c8db5f6c6
Gitweb:        https://git.kernel.org/tip/1a39340865ce505a029b37aeb47a3e4c8db5f6c6
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Tue, 27 Oct 2020 13:48:34 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 30 Oct 2020 17:07:18 +01:00

lockdep: Fix nr_unused_locks accounting

Chris reported that commit 24d5a3bffef1 ("lockdep: Fix
usage_traceoverflow") breaks the nr_unused_locks validation code
triggered by /proc/lockdep_stats.

By fully splitting LOCK_USED and LOCK_USED_READ it becomes a bad
indicator for accounting nr_unused_locks; simplyfy by using any first
bit.

Fixes: 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow")
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://lkml.kernel.org/r/20201027124834.GL2628@hirez.programming.kicks-ass.net
---
 kernel/locking/lockdep.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 1102849..b71ad8d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4396,6 +4396,9 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 	if (unlikely(hlock_class(this)->usage_mask & new_mask))
 		goto unlock;
 
+	if (!hlock_class(this)->usage_mask)
+		debug_atomic_dec(nr_unused_locks);
+
 	hlock_class(this)->usage_mask |= new_mask;
 
 	if (new_bit < LOCK_TRACE_STATES) {
@@ -4403,19 +4406,10 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 			return 0;
 	}
 
-	switch (new_bit) {
-	case 0 ... LOCK_USED-1:
+	if (new_bit < LOCK_USED) {
 		ret = mark_lock_irq(curr, this, new_bit);
 		if (!ret)
 			return 0;
-		break;
-
-	case LOCK_USED:
-		debug_atomic_dec(nr_unused_locks);
-		break;
-
-	default:
-		break;
 	}
 
 unlock:

  parent reply	other threads:[~2020-10-31 11:30 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-29 14:31 lockdep null-ptr-deref Qian Cai
2020-09-29 23:08 ` Boqun Feng
2020-09-30  9:16   ` Peter Zijlstra
2020-09-30  9:49     ` Peter Zijlstra
2020-09-30 12:18       ` Boqun Feng
2020-09-30 19:02         ` Peter Zijlstra
2020-10-02 12:36           ` Boqun Feng
2020-10-02 13:09             ` Peter Zijlstra
2020-10-02 13:35               ` Boqun Feng
2020-10-02 10:06       ` Peter Zijlstra
2020-10-02 13:40         ` Qian Cai
2020-10-07 16:20       ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra
2020-10-27 11:29         ` Chris Wilson
2020-10-27 11:59           ` Peter Zijlstra
2020-10-27 12:30             ` Peter Zijlstra
2020-10-27 12:48               ` Peter Zijlstra
2020-10-27 14:13                 ` Chris Wilson
2020-10-31 11:30                 ` tip-bot2 for Peter Zijlstra [this message]
2020-10-27 13:29               ` Chris Wilson
2020-10-27 15:45                 ` Peter Zijlstra
2020-10-27 16:34                   ` Chris Wilson
2020-10-28 17:40                     ` Chris Wilson
2020-10-28 18:06                       ` Chris Wilson
2020-10-28 19:42                       ` Peter Zijlstra
2020-10-28 19:59                         ` Peter Zijlstra
2020-10-30  3:51                           ` Boqun Feng
2020-10-30  9:38                             ` Peter Zijlstra
2020-10-30  9:55                               ` Peter Zijlstra
2020-11-02  5:37                               ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-02  5:37                                 ` [PATCH 2/2] lockdep/selftest: Add spin_nest_lock test Boqun Feng
2020-12-03 10:35                                   ` [tip: locking/core] " tip-bot2 for Boqun Feng
2020-11-05  6:25                                 ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-10 17:28                                 ` Peter Zijlstra
2020-11-11  8:23                                 ` [tip: locking/urgent] " tip-bot2 for Boqun Feng
2020-10-09  7:58       ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra

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