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From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] markers: fix unregister bug and reenter bug
Date: Mon, 29 Sep 2008 11:03:20 -0400	[thread overview]
Message-ID: <20080929150320.GA11245@Krystal> (raw)
In-Reply-To: <48E08B05.7030802@cn.fujitsu.com>

Hi Lai,

I'll have to nack this fix :

One fix I already posted makes sure every marker unregister callers call
synchronize_sched() _at some point_ before module unload. It thus makes
sure we can do batch unregistration without doing multiple
synchronize_sched calls.

Also, there is no need to do the synchronize_sched with the marker mutex
held. call_rcu_sched takes care of making sure the previous quiescent
state is over before calling kfree. This means that when we return from
the register/unregister functions, there may still be markers "in
flight" using the old markers. Again, why would it be a problem ?

Thanks,

Mathieu

P.S. : I'll send along the patches I am referring to. Ingo, those should
probably be merged if they are not in -tip already.

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

  parent reply	other threads:[~2008-09-29 15:03 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-29  8:00 [PATCH] markers: fix unregister bug and reenter bug Lai Jiangshan
2008-09-29  8:27 ` Ingo Molnar
2008-09-29 15:03   ` Mathieu Desnoyers
2008-09-29 15:05   ` [PATCH] Markers : marker_synchronize_unregister() Mathieu Desnoyers
2008-09-30  1:47     ` Lai Jiangshan
     [not found]     ` <20081002235650.43ca075c.akpm@linux-foundation.org>
2008-10-03 15:52       ` [PATCH] Markers synchronize unregister static inline Mathieu Desnoyers
2008-10-03 17:31         ` Ingo Molnar
2008-09-29 15:06   ` [PATCH] RCU read sched Mathieu Desnoyers
2008-09-30 10:08     ` Ingo Molnar
2008-09-30 13:10       ` Paul E. McKenney
2008-09-30 13:10     ` Paul E. McKenney
2008-09-29 15:08   ` [PATCH] Markers use rcu_read_lock_sched() Mathieu Desnoyers
2008-09-30 10:13     ` Ingo Molnar
2008-09-29 15:09   ` [PATCH] Markers : probe example fix teardown Mathieu Desnoyers
2008-09-29 15:10   ` [PATCH] Markers : documentation " Mathieu Desnoyers
2008-09-29 15:11   ` [PATCH] sputrace : use marker_synchronize_unregister() Mathieu Desnoyers
2008-09-29 15:11     ` Mathieu Desnoyers
2008-09-29 15:13     ` Christoph Hellwig
2008-09-29 15:13       ` Christoph Hellwig
2008-09-30  0:28     ` Jeremy Kerr
2008-09-30  0:28       ` Jeremy Kerr
2008-09-30  9:55       ` Ingo Molnar
2008-09-30  9:55         ` Ingo Molnar
2008-09-30 11:22         ` [Cbe-oss-dev] " Jeremy Kerr
2008-09-30 11:22           ` Jeremy Kerr
2008-09-30 11:30           ` Ingo Molnar
2008-09-30 11:30             ` Ingo Molnar
2008-09-30 11:34             ` Jeremy Kerr
2008-09-30 11:34               ` Jeremy Kerr
2008-09-29 15:03 ` Mathieu Desnoyers [this message]
2008-09-30  1:40   ` [PATCH] markers: fix unregister bug and reenter bug Lai Jiangshan
2008-09-30  3:38     ` Mathieu Desnoyers

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