Re: [PATCH v2] lockdep: Let lock_is_held_type() detect recursive read as read

From: Waiman Long
Date: Wed Sep 08 2021 - 10:35:52 EST


On 9/3/21 4:40 AM, Sebastian Andrzej Siewior wrote:
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@xxxxxxxxxxxxx>
---
v1…v2:
- 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 = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
- if (read == -1 || hlock->read == read)
+ if (read == -1 || hlock->read == !!read)
return LOCK_STATE_HELD;
return LOCK_STATE_NOT_HELD;

Thanks for accepting my suggestion.

Acked-by: Waiman Long <longman@xxxxxxxxxx>