From: Peter Zijlstra <peterz@infradead.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: mingo@redhat.com, linux-kernel@vger.kernel.org,
Will Deacon <will.deacon@arm.com>, Tejun Heo <tj@kernel.org>,
Johannes Berg <johannes.berg@intel.com>
Subject: Re: [PATCH 1/2] locking/lockdep: Add support for dynamic depmaps and keys
Date: Sat, 10 Nov 2018 14:55:24 +0100 [thread overview]
Message-ID: <20181110135524.GC3339@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20181109234645.10530-2-bvanassche@acm.org>
On Fri, Nov 09, 2018 at 03:46:44PM -0800, Bart Van Assche wrote:
> The lock validator forces to categorize multiple instances of a lock object
> as the same lock class because it requires that struct lockdep_map and struct
> lock_class_key instances are static objects. This can result in false
> positive lockdep reports that are hard to suppress in an elegant way. Hence
> add support for allocating instances of these objects dynamically.
Yeah, I think not. You completely fail to explain how what you propose
is correct.
The thing is; we rely on static objects because they provide
persistence. Their address will never be re-used.
Dynamic objects do not provide this same guarantee. And when you re-use
the key address for something else, you'll mix the chains and things
come unstuck.
next prev parent reply other threads:[~2018-11-10 22:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-09 23:46 [PATCH 0/2] locking/lockdep: Support dynamic lockdep keys Bart Van Assche
2018-11-09 23:46 ` [PATCH 1/2] locking/lockdep: Add support for dynamic depmaps and keys Bart Van Assche
2018-11-10 13:55 ` Peter Zijlstra [this message]
2018-11-19 21:55 ` Bart Van Assche
2018-11-09 23:46 ` [PATCH 2/2] kernel/workqueue: Use dynamic lockdep keys for workqueues Bart Van Assche
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