Re: [RFC PATCH] tools lib traceevent: Allow setting an alternative symbol resolver

[Steven Rostedt <rostedt@goodmis.org>]

On Thu, 23 Jul 2015 18:58:36 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> Em Thu, Jul 23, 2015 at 06:52:46PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Jul 23, 2015 at 05:35:24PM -0400, Steven Rostedt escreveu:
> > > On Thu, 23 Jul 2015 18:25:36 -0300
> > > Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > > > +	if (resolver == NULL) {
> > > > +		errno = ENOMEM;
> > > 
> > > Why set errno, wont a failed malloc set it for us?
> > 
> > Humm, I thought about that, I've read malloc's man page and it doesn't
> > mention that... in the return section, but later, in NOTES, it says
> > UNIX98 requires that and glibc does it, so I'm ditching this...
> 
> > > Also I wonder if we should add a way to clear the resolver. That is,
> > > you want to use the default resolver?
> > 
> > I am adding a reset_function_resolver(pevent);
> >  
> > > Not really a necessity, as I don't see any current programs using it,
> > > but it would complete the interface.
> 
> One more try:

Third time's a charm, or was this the forth?

Reviewed-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> 
> commit 212a2417baaa89168cbe3112fe7c8efaddee28b8
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date:   Wed Jul 22 12:36:55 2015 -0300
> 
>     tools lib traceevent: Allow setting an alternative symbol resolver
>     
>     The perf tools have a symbol resolver that includes solving kernel
>     symbols using either kallsyms or ELF symtabs, and it also is using
>     libtraceevent to format the trace events fields, including via
>     subsystem specific plugins, like the "timer" one.
>     
>     To solve fields like "timer:hrtimer_start"'s "function", libtraceevent
>     needs a way to map from its value to a function name and addr.
>     
>     This patch provides a way for tools that already have symbol resolving
>     facilities to ask libtraceevent to use it when needing to resolve
>     kernel symbols.
>     
>     Acked-by: David Ahern <dsahern@gmail.com>
>     Cc: Adrian Hunter <adrian.hunter@intel.com>
>     Cc: Borislav Petkov <bp@suse.de>
>     Cc: Frederic Weisbecker <fweisbec@gmail.com>
>     Cc: Jiri Olsa <jolsa@redhat.com>
>     Cc: Namhyung Kim <namhyung@kernel.org>
>     Cc: Stephane Eranian <eranian@google.com>
>     Cc: Steven Rostedt <rostedt@goodmis.org>
>     Link: http://lkml.kernel.org/n/tip-fdx1fazols17w5py26ia3bwh@git.kernel.org
>     Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>