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Date: Sat, 9 May 2009 16:07:17 +0200
From: Ingo Molnar <mingo@elte.hu>
To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>, Tom Zanussi <tzanussi@gmail.com>,
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       peterz@infradead.org, mathieu.desnoyers@polymtl.ca, jiayingz@google.com,
       mbligh@google.com, roland@redhat.com, fche@redhat.com
Subject: Re: [RFC] convert ftrace syscall tracer to TRACE_EVENT()
Message-ID: <20090509140717.GB22000@elte.hu>
References: <20090508210347.GA3121@redhat.com> <20090509083737.GE3656@elte.hu> <c62985530905090553u538f8589l984b03428713d7ef@mail.gmail.com> <20090509133306.GA20684@elte.hu> <c62985530905090702o536c8787m1910540d560a0a22@mail.gmail.com>
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* Frédéric Weisbecker <fweisbec@gmail.com> wrote:

> > Note, this assumes that all syscall types can be described via 
> > __field() - i think that's correct. (we dont want to deref 
> > strings as they are untrusted, and there are no arrays in 
> > syscall parameters)
> 
> Yeah, but we can also define a __string_from_user(), should be 
> trivial.

We cannot really do that, because we cannot check the type in a 
macro. So we dont know when to inject __field() versus 
__string_from_user().

> > Can you see any complication?
> 
> Just about the order of headers to include and headers 
> dependencies....

That is testable and any problems will be found at the build stage, 
so it should be solvable.

	Ingo