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From: Wang YanQing <udknight@gmail.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: mingo@elte.hu, paulmck@linux.vnet.ibm.com,
	linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl,
	deepthi@linux.vnet.ibm.com, peterz@infradead.org,
	rusty@rustcorp.com.au, heiko.carstens@de.ibm.com,
	rostedt@goodmis.org, miltonm@bga.com,
	srivatsa.bhat@linux.vnet.ibm.com, tj@kernel.org,
	akpm@linux-foundation.org, svaidy@linux.vnet.ibm.com,
	shli@kernel.org, tglx@linutronix.de, lig.fnst@cn.fujitsu.com,
	anton@samba.org
Subject: Re: [PATCH 3/3] smp/ipi:Remove check around csd lock in handler for smp_call_function variants
Date: Mon, 8 Jul 2013 01:25:41 +0800	[thread overview]
Message-ID: <20130707172541.GA3218@udknight> (raw)
In-Reply-To: <51D99614.303@linux.vnet.ibm.com>

On Sun, Jul 07, 2013 at 09:53:48PM +0530, Preeti U Murthy wrote:
> > "
> >  /*                                                                                               
> >   * Unlocked CSDs are valid through generic_exec_single():                                        
> >   */
> 
> I don't understand this comment. All callers of generic_exec_single()
> take the csd lock. So where is the scenario of csds being unlocked in
> generic_exec_single() before the call to
> arch_send_call_function_single_ipi() is made?
>   Rather what is the above comment trying to say?

I have given the answer to this question in last reply.

I don't know whether it is right to make a assumption through
this way that what you do currently:

Find all the current api users, and drop all the robust codes,
despite the unpredictable future users.

Ok, I know the balance between "robust" vs "performance",
robust check codes will bring performance penalty in fastest
code path, but the "penalty" is neglectable sometimes for
modern CPU.

I decide to respect the MAINTAINER's decision to accept this 
change or not.

Thanks.




      reply	other threads:[~2013-07-07 17:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-05 16:26 [PATCH 0/3] smp/ipi: Minor cleanups in smp_call_function variants Preeti U Murthy
2013-07-05 16:27 ` [PATCH 1/3] smp/ipi: Remove redundant cfd->cpumask_ipi mask Preeti U Murthy
2013-07-06  3:13   ` Wang YanQing
2013-07-06  5:29     ` Preeti U Murthy
2013-07-06  6:03       ` Wang YanQing
2013-07-07 16:45         ` Preeti U Murthy
2013-07-05 16:27 ` [PATCH 2/3] smp/ipi:Clarify ambiguous comments around deadlock scenarios in smp_call_function variants Preeti U Murthy
2013-07-06  6:12   ` Wang YanQing
2013-07-06  7:48     ` Preeti U Murthy
2013-07-06 19:48       ` Thomas Gleixner
2013-07-07 16:29         ` Preeti U Murthy
2013-07-05 16:27 ` [PATCH 3/3] smp/ipi:Remove check around csd lock in handler for " Preeti U Murthy
2013-07-06  5:45   ` Wang YanQing
2013-07-06  8:06     ` Preeti U Murthy
2013-07-06 14:21       ` Wang YanQing
2013-07-07 16:23         ` Preeti U Murthy
2013-07-07 17:25           ` Wang YanQing [this message]

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