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Subject: Re: [PATCH v4 1/2] locking/rwsem: Add DEBUG_RWSEMS to look for
 lock/unlock mismatches
To:     Davidlohr Bueso <dave@stgolabs.net>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org
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From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <7a38857b-37eb-0860-75c2-c9bf00622377@redhat.com>
Date:   Thu, 29 Mar 2018 11:17:57 -0400
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On 03/29/2018 11:01 AM, Davidlohr Bueso wrote:
> On Thu, 29 Mar 2018, Waiman Long wrote:
>
>> Because it checks the owner field which is present only if
>> RWSEM_SPIN_ON_OWNER is defined. Mutex is different in the sense that the
>> owner field is always there no matter if MUTEX_SPIN_ON_OWNER is set
>> or not.
>
> Ah right; that's after Peter's mutex rewrite iirc. No objections from me.
>
> Acked-by: Davidlohr Bueso <dave@stgolabs.net>

In reality, I think RWSEM_SPIN_ON_OWNER is almost always set if the xadd
version of rwsem is used. So we may do some cleanup here if necessary.

-Longman