Message-ID: <49EFA0DE.9070407@redhat.com>
Date: Wed, 22 Apr 2009 18:57:34 -0400
From: Masami Hiramatsu <mhiramat@redhat.com>
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To: Tim Abbott <tabbott@MIT.EDU>
CC: Ingo Molnar <mingo@elte.hu>, Rusty Russell <rusty@rustcorp.com.au>,
       Steven Rostedt <rostedt@goodmis.org>, linux-kernel@vger.kernel.org,
       Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Anders Kaseorg <andersk@MIT.EDU>, Jeffrey B Arnold <jbarnold@MIT.EDU>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Subject: Re: [PATCH 1/5] ftrace: use module notifier for function tracer
References: <20090416021830.556671772@goodmis.org> <20090416021928.040177084@goodmis.org> <200904192055.04213.rusty@rustcorp.com.au> <alpine.DEB.1.10.0904191437250.31802@vinegar-pot.mit.edu> <20090422091645.GB18226@elte.hu> <alpine.DEB.1.10.0904221250280.24280@vinegar-pot.mit.edu>
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Tim Abbott wrote:
> On Wed, 22 Apr 2009, Ingo Molnar wrote:
> 
>> I suspect ksplice could make use of text_mutex?
> 
> Yes, this is what I was imagining.  Thanks for pointing this out!  I plan 
> to make Ksplice use this for the next version of the Ksplice patch series.

Could you also add "use text_poke() on x86" to your plan? :-)

> However, since Ksplice can be built as a module, we'll want to 
> EXPORT_SYMBOL_GPL(text_mutex).  The comment above text_mutex's definition 
> suggests some people would prefer not to have modules patching the kernel 
> text, and so this point might be contentious.  I've found support for 
> building Ksplice as a module to be a useful feature in case one needs to 
> use multiple different versions of Ksplice on the same system (e.g. 
> because the version built in to the kernel doesn't support a particular 
> patch).

Hmm, I can't agree that we allow module to modify kernel text...
Is that possible to separate kernel-text swapping routine from Ksplice
module? In that case, we don't need to export text_mutex.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

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