linux-kernel - Re: [PATCH 3/3] smp/ipi:Remove check around csd lock in handler for smp_call

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Date:	Sat, 6 Jul 2013 22:21:52 +0800
From:	Wang YanQing <udknight@...il.com>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Cc:	mingo@...e.hu, paulmck@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, a.p.zijlstra@...llo.nl,
	deepthi@...ux.vnet.ibm.com, peterz@...radead.org,
	rusty@...tcorp.com.au, heiko.carstens@...ibm.com,
	rostedt@...dmis.org, miltonm@....com,
	srivatsa.bhat@...ux.vnet.ibm.com, tj@...nel.org,
	akpm@...ux-foundation.org, svaidy@...ux.vnet.ibm.com,
	shli@...nel.org, tglx@...utronix.de, lig.fnst@...fujitsu.com,
	anton@...ba.org
Subject: Re: [PATCH 3/3] smp/ipi:Remove check around csd lock in handler for
 smp_call_function variants

On Sat, Jul 06, 2013 at 01:36:27PM +0530, Preeti U Murthy wrote:
> Ideally it should be under a WARN_ON(). csd_unlock() has that WARN_ON().
> Unlocking a parameter which is not locked should be seen as a bug, which
> the above code is not doing. In fact it avoids it being reported as a bug.

Although I know what's your meaning, but just like the comment in code:

"
 /*                                                                                               
  * Unlocked CSDs are valid through generic_exec_single():                                        
  */
"

If the csd don't come from generic_exec_single, then
Unlocked CSDs maybe are not valid. So we check CSD_FLAG_LOCK
to avoid trigger the WARN_ON in csd_unlock.

Genric_exec_single's name imply it is a generic version,
you know, maybe we will have "special" version.

Thanks.
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