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Date:   Fri, 3 Sep 2021 10:40:01 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Waiman Long <llong@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH v2] lockdep: Let lock_is_held_type() detect recursive read as
 read
Message-ID: <20210903084001.lblecrvz4esl4mrr@linutronix.de>
References: <20210901162255.u2vhecaxgjsjfdtc@linutronix.de>
 <9af2b074-9fcf-5aea-f37d-9b2482146489@redhat.com>
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lock_is_held_type(, 1) detects acquired read locks. It only recognized
locks acquired with lock_acquire_shared(). Read locks acquired with
lock_acquire_shared_recursive() are not recognized because a `2' is
stored as the read value.

Rework the check to additionally recognise lock's read value one and two
as a read held lock.

Fixes: e918188611f07 ("locking: More accurate annotations for read_lock()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v1=E2=80=A6v2:
  - simplify the read check to !!read as suggested by Waiman Long.

 kernel/locking/lockdep.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5366,7 +5366,7 @@ int __lock_is_held(const struct lockdep_
 		struct held_lock *hlock =3D curr->held_locks + i;
=20
 		if (match_held_lock(hlock, lock)) {
-			if (read =3D=3D -1 || hlock->read =3D=3D read)
+			if (read =3D=3D -1 || hlock->read =3D=3D !!read)
 				return LOCK_STATE_HELD;
=20
 			return LOCK_STATE_NOT_HELD;