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Date: Mon, 23 Mar 2015 12:02:28 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>, Jiri Olsa <jolsa@kernel.org>,
        linux-kernel@vger.kernel.org, Adrian Hunter <adrian.hunter@intel.com>,
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        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Stephane Eranian <eranian@google.com>, acme@kernel.org
Subject: Re: [PATCH 08/14] perf tools: Use kmod_path__parse in
 map_groups__set_modules_path_dir
Message-ID: <20150323110228.GC21860@krava.brq.redhat.com>
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 <20150321182042.GB3404@redhat.com>
 <20150322235509.GA2782@sejong>
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On Mon, Mar 23, 2015 at 08:55:09AM +0900, Namhyung Kim wrote:

SNIP

> > > +	 */
> > > +	if (m->comp && is_kmod_dso(map->dso))
> > > +		map->dso->symtab_type++;
> > 
> > Ouch, does this assumes this is a:
> > 
> > DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE
> 
> Nope, it's one of _SYSTEM_PATH_KMODULE or _GUEST_KMODULE.
> 
> 
> > 
> > And that, because in the dso_binary_type enum
> > DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP comes right after it, and thus
> > this cryptic increment is equivalent to:
> > 
> > 		map->dso->symtab_type = DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP;
> 
> Again, _SYSTEM_PATH_KMODULE_COMP or _GUEST_KMODULE_COMP.
> 

yep, the code assumes (correctly) that symtab_type is
either _SYSTEM_PATH_KMODULE or _GUEST_KMODULE.

Namhyung placed the _COMP enum right behind 'no comp' values:

enum dso_binary_type {
	...
        DSO_BINARY_TYPE__GUEST_KMODULE,
        DSO_BINARY_TYPE__GUEST_KMODULE_COMP,
        DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE,
        DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP,
	...

so we could safely just increase the symtab_type in case
we detect it's compressed kernel module.

Perhaps the code could be more verbose on this, but since such
comment wasn't part of the previous code I did not feel the need
to add it now ;-)

jirka