From: Waiman Long <llong@redhat.com>
To: Boqun Feng <boqun.feng@gmail.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Waiman Long <llong@redhat.com>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2] lockdep: Let lock_is_held_type() detect recursive read as read
Date: Wed, 8 Sep 2021 10:40:14 -0400 [thread overview]
Message-ID: <959eddbd-799b-3b10-0f30-0209f883d5ed@redhat.com> (raw)
In-Reply-To: <YTgc8xXuVlpOhoUT@boqun-archlinux>
On 9/7/21 10:16 PM, Boqun Feng wrote:
> On Fri, Sep 03, 2021 at 10:40:01AM +0200, 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@linutronix.de>
>> ---
>> 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)
> I think this should be:
>
> !!hlock->read == read
>
> With that,
>
> Acked-by: Boqun Feng <boqun.feng@gmail.com>
>
You are right. It should be the other way around. read can only be -1,
0, 1 while hlock->read can be 0, 1, 2.
Cheers,
Longman
next prev parent reply other threads:[~2021-09-08 14:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 16:22 [PATCH] lockdep: Let lock_is_held_type() detect recursive read as read Sebastian Andrzej Siewior
2021-09-01 16:43 ` 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 ` Waiman Long [this message]
2021-09-08 14:35 ` [PATCH v2] " Waiman Long
2021-09-17 13:17 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
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