linux-kernel - Re: [PATCH v2 5/6] locking/lockdep: Decrement irq context counters when removing lock chain

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Message-ID: <0ea82499-af07-6193-9672-4a1050442ada@redhat.com>
Date:   Tue, 14 Jan 2020 10:04:26 -0500
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will.deacon@....com>,
        linux-kernel@...r.kernel.org, Bart Van Assche <bvanassche@....org>
Subject: Re: [PATCH v2 5/6] locking/lockdep: Decrement irq context counters
 when removing lock chain

On 1/14/20 4:53 AM, Peter Zijlstra wrote:
> On Mon, Dec 16, 2019 at 10:15:16AM -0500, Waiman Long wrote:
>> There are currently three counters to track the irq context of a lock
>> chain - nr_hardirq_chains, nr_softirq_chains and nr_process_chains.
>> They are incremented when a new lock chain is added, but they are
>> not decremented when a lock chain is removed. That causes some of the
>> statistic counts reported by /proc/lockdep_stats to be incorrect.
>>
>> Fix that by decrementing the right counter when a lock chain is removed.
>>
>> Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use")
>> Signed-off-by: Waiman Long <longman@...hat.com>
> Fixes go at the start of a series, because if the depend on prior
> patches (as this one does) we cannot apply them.
>
Will put it at the front in the next version.

Cheers,
Longman