From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH] lockdep: Let lock_is_held_type() detect recursive read as read
Date: Wed, 1 Sep 2021 18:22:55 +0200 [thread overview]
Message-ID: <20210901162255.u2vhecaxgjsjfdtc@linutronix.de> (raw)
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>
---
On a related note: What exactly means read_lock_is_recursive() in terms
of recursive locking? The second items mentions QRW locks. Does this
mean that a pending WRITER blocks further READER from acquiring the
lock?
kernel/locking/lockdep.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index f15df3fd7c5a6..39f98454a8827 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5366,7 +5366,9 @@ int __lock_is_held(const struct lockdep_map *lock, int read)
struct held_lock *hlock = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
- if (read == -1 || hlock->read == read)
+ if (read == -1 ||
+ (read == 0 && hlock->read == 0) ||
+ (read == 1 && hlock->read > 0))
return LOCK_STATE_HELD;
return LOCK_STATE_NOT_HELD;
--
2.33.0
next reply other threads:[~2021-09-01 16:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 16:22 Sebastian Andrzej Siewior [this message]
2021-09-01 16:43 ` [PATCH] lockdep: Let lock_is_held_type() detect recursive read as read Boqun Feng
2021-09-03 10:45 ` Sebastian Andrzej Siewior
2021-09-03 14:15 ` Boqun Feng
2021-09-03 14:30 ` Sebastian Andrzej Siewior
2021-09-01 18:32 ` Waiman Long
2021-09-03 8:40 ` [PATCH v2] " Sebastian Andrzej Siewior
2021-09-08 2:16 ` Boqun Feng
2021-09-08 10:17 ` Peter Zijlstra
2021-09-10 13:53 ` [PATCH v3] " Sebastian Andrzej Siewior
2021-09-08 14:40 ` [PATCH v2] " Waiman Long
2021-09-08 14:35 ` Waiman Long
2021-09-17 13:17 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
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