linux-kernel - Re: [PATCH RFC 00/11] lock monitor: Separate features related to lock

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Message-ID: <4BA4638C.40307@dcl.info.waseda.ac.jp>
Date:	Sat, 20 Mar 2010 14:56:28 +0900
From:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
To:	Frederic Weisbecker <fweisbec@...il.com>
CC:	Jason Baron <jbaron@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, h.mitake@...il.com,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [PATCH RFC 00/11] lock monitor: Separate features related to
 lock

On 03/19/10 06:16, Frederic Weisbecker wrote:
 >> And I have a question related to this dynamic patching approach for 
lockdep.
 >> If dynamic proving turning on/off is provided,
 >> lockdep will be confused by inconsistency of lock acquiring log.
 >>
 >> Will the sequence,
 >>
 >> lock_acquire(l) ->  turning off ->  lock_release(l) ->  turning on ->
 >> lock_acquire(l)
 >>
 >> detected as double acquiring?
 >>
 >> Should turning on/off lockdep be done in the time
 >> when every processes have no lock?
 >
 >
 > There is almost always a process with a lock somewhere ;-)

Yeah :)

 >
 > This is not a big deal, it's very similar to unfinished scenarios
 > due to the end of the tracing that can happen anytime and you miss
 > a lock_release or whatever. We can also begin the tracing anytime,
 > and you may receive orphan lock_release in the very beginning
 > because you missed the lock_acquire that happened before the tracing.
 >
 > Any locking scenario that doesn't fit into the state machine
 > or is incomplete must be considered as broken and then ignored.
 >
 >

I see, thanks.
I have to fix state machine of perf lock.
Now it doesn't consider read, try and orphan events,
it is very incompletely..
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