Date: Tue, 4 Dec 2007 11:39:54 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: linux-kernel@vger.kernel.org, hch@infradead.org, mmlnx@us.ibm.com,
       dipankar@in.ibm.com, dsmith@redhat.com, paulmck@us.ibm.com
Subject: Re: [patch 1/2] Linux Kernel Markers - Support Multiple Probes
Message-Id: <20071204113954.c1dc9d87.akpm@linux-foundation.org>
In-Reply-To: <20071204192100.GB31752@Krystal>
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	<20071204182402.940135178@polymtl.ca>
	<20071204110648.dd918789.akpm@linux-foundation.org>
	<20071204192100.GB31752@Krystal>
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On Tue, 4 Dec 2007 14:21:00 -0500
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> > > + */
> > > +void marker_probe_cb(const struct marker *mdata, void *call_private,
> > > +	const char *fmt, ...)
> > > +{
> > > +	va_list args;
> > > +	char ptype;
> > > +
> > > +	preempt_disable();
> > 
> > What are the preempt_disable()s doing in here?
> > 
> > Unless I missed something obvious, a comment is needed here (at least).
> > 
> 
> They make sure the teardown of the callbacks can be done correctly when
> they are in modules and they insure RCU read coherency. Will add
> comment.

So shouldn't it be using rcu_read_lock()?  If that does not suit, should we
be adding new rcu primitives rather than open-coding and adding dependencies?
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