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Date: Wed, 12 Mar 2003 19:54:28 -0500 (EST)
From: Zwane Mwaikambo <zwane@holomorphy.com>
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To: Paul McKenney <Paul.McKenney@us.ibm.com>
cc: David Miller <davem@redhat.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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       Stephen Hemminger <shemminger@osdl.org>,
       Linus Torvalds <torvalds@transmeta.com>
Subject: Re: [PATCH] (1/8) Eliminate brlock in psnap
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On Wed, 12 Mar 2003, Paul McKenney wrote:

> You are saying that we can omit locking because this is
> called only from a module-exit function, and thus protected
> by the module_mutex semaphore?  (I must defer to
> others who have a better handle on modules...)
> 
> If in fact only one module-exit function can be
> executing at a given time, then we should be able to
> use the following approach:

Yes the ->exit call is protected by module_mutex globally.
 
> Module unloading should be rare enough to tolerate
> the grace period under the module_mutex, right?
> 
> Thoughts?

I would agree. However can't unregister_snap_client be used in other paths 
apart from module_unload? I wouldn't worry too much since if 
register_snap_client and unregister_snap_client for the same protocol 
races it's a bug in the caller's code. The safe RCU list removal and 
synchronize_kernel should protect us from sane usage.

	Zwane
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