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Date: Wed, 1 Oct 2008 19:47:19 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Pekka Paalanen <pq@iki.fi>, linux-kernel@vger.kernel.org,
       Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Mathieu Desnoyers <compudj@krystal.dyndns.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Steven Rostedt <srostedt@redhat.com>
Subject: Re: [PATCH] ftrace: type cast verifier
Message-ID: <20081001174719.GA21089@elte.hu>
References: <20080930030236.230994826@goodmis.org> <20080930030652.883661046@goodmis.org> <20080930203342.5b5ca814@daedalus.pq.iki.fi> <alpine.DEB.1.10.0809301341300.6224@gandalf.stny.rr.com> <20081001075419.GA24509@elte.hu> <alpine.DEB.1.10.0810011052130.30777@gandalf.stny.rr.com> <20081001174236.GA19954@elte.hu>
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* Ingo Molnar <mingo@elte.hu> wrote:

> could you rename it to trace_type() - that way the initialization could 
> be written in a more compact way as:
> 
> > +	struct trace_mmiotrace_map *field = trace_type(field, entry);

ah, it cannot be done that way, as 'field' has to be known to the 
compiler.

so your patch is fine as-is, the extra line is an acceptable cost, as we 
get:

- the type filter (trying to cast an object outside of the narrow list 
  of trace entry types will cause a failed build - i.e. most of the 
  practical dangers of C type casting are avoided!)

- the runtime entry type checker

	Ingo