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Date: Sat, 20 Mar 2010 14:56:28 +0900
From: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: Jason Baron <jbaron@redhat.com>, Steven Rostedt <rostedt@goodmis.org>,
       Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
       Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <peterz@infradead.org>,
       linux-kernel@vger.kernel.org, h.mitake@gmail.com,
       Paul Mackerras <paulus@samba.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH RFC 00/11] lock monitor: Separate features related to
 lock
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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..