linux-kernel - Re: [PATCH 3/4] perf tools: Add initialized arg into unwind__prepare

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Date:	Mon, 4 Jul 2016 16:25:11 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Jiri Olsa <jolsa@...nel.org>
Cc:	He Kuang <hekuang@...wei.com>, lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 3/4] perf tools: Add initialized arg into
 unwind__prepare_access

Em Mon, Jul 04, 2016 at 02:16:22PM +0200, Jiri Olsa escreveu:
> Adding initialized arg into unwind__prepare_access
> to get feedback about the initialization state.
> 
> It's not possible to get it from error code, because
> we return 0 even in case we don't recognize dso, which
> is valid.
> 
> The 'initialized' value is used in following patch
> to speedup unwind__prepare_access calls logic in
> fork path.
> 
> Cc: He Kuang <hekuang@...wei.com>
> Link: http://lkml.kernel.org/n/tip-vzmw5piz7diqa7rd6c49mjph@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/thread.c           |  2 +-
>  tools/perf/util/unwind-libunwind.c | 11 +++++++++--
>  tools/perf/util/unwind.h           |  9 ++++++---
>  3 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index f30f9566fddc..2439b122a4e4 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -202,7 +202,7 @@ int thread__insert_map(struct thread *thread, struct map *map)
>  {
>  	int ret;
>  
> -	ret = unwind__prepare_access(thread, map);
> +	ret = unwind__prepare_access(thread, map, NULL);
>  	if (ret)
>  		return ret;
>  
> diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
> index 854711966cad..6d542a4e0648 100644
> --- a/tools/perf/util/unwind-libunwind.c
> +++ b/tools/perf/util/unwind-libunwind.c
> @@ -14,15 +14,19 @@ static void unwind__register_ops(struct thread *thread,
>  	thread->unwind_libunwind_ops = ops;
>  }
>  
> -int unwind__prepare_access(struct thread *thread, struct map *map)
> +int unwind__prepare_access(struct thread *thread, struct map *map,
> +			   bool *initialized)
>  {
>  	const char *arch;
>  	enum dso_type dso_type;
>  	struct unwind_libunwind_ops *ops = local_unwind_libunwind_ops;
> +	int err;
>  
>  	if (thread->addr_space) {
>  		pr_debug("unwind: thread map already set, dso=%s\n",
>  			 map->dso->name);
> +		if (initialized)
> +			*initialized = true;
>  		return 0;
>  	}
>  
> @@ -51,7 +55,10 @@ int unwind__prepare_access(struct thread *thread, struct map *map)
>  out_register:
>  	unwind__register_ops(thread, ops);
>  
> -	return thread->unwind_libunwind_ops->prepare_access(thread);
> +	err = thread->unwind_libunwind_ops->prepare_access(thread);
> +	if (initialized)
> +		*initialized = err ? false : true;
> +	return err;
>  }
>  
>  void unwind__flush_access(struct thread *thread)
> diff --git a/tools/perf/util/unwind.h b/tools/perf/util/unwind.h
> index 84c6d44d52f9..17ea1f928f13 100644
> --- a/tools/perf/util/unwind.h
> +++ b/tools/perf/util/unwind.h
> @@ -42,12 +42,14 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
>  #endif
>  
>  int LIBUNWIND__ARCH_REG_ID(int regnum);
> -int unwind__prepare_access(struct thread *thread, struct map *map);
> +int unwind__prepare_access(struct thread *thread, struct map *map,
> +			   bool *initialized);
>  void unwind__flush_access(struct thread *thread);
>  void unwind__finish_access(struct thread *thread);
>  #else
>  static inline int unwind__prepare_access(struct thread *thread __maybe_unused,
> -					 struct map *map __maybe_unused)
> +					 struct map *map __maybe_unused,
> +					 bool *initialized __maybe_unused);
>  {
>  	return 0;
>  }
> @@ -67,7 +69,8 @@ unwind__get_entries(unwind_entry_cb_t cb __maybe_unused,
>  }
>  
>  static inline int unwind__prepare_access(struct thread *thread __maybe_unused,
> -					 struct map *map __maybe_unused)
> +					 struct map *map __maybe_unused,
> +					 bool *initialized __maybe_unused);
>  {
>  	return 0;
>  }

That extra ; breaks the build on centos5 (i.e. on an arch where the
above code gets compiled:

  CC       /tmp/build/perf/bench/sched-pipe.o
In file included from util/machine.c:14:
util/unwind.h:74: error: expected identifier or '(' before '{' token
  MKDIR    /tmp/build/perf/tests/
  CC       /tmp/build/perf/tests/parse-events.o
mv: cannot stat `/tmp/build/perf/util/.machine.o.tmp': No such file or directory
make[3]: *** [/tmp/build/perf/util/machine.o] Error 1
make[3]: *** Waiting for unfinished jobs....
  MKDIR    /tmp/build/perf/tests/
  CC       /tmp/build/perf/tests/dso-data.o
make[2]: *** [util] Error 2
make[1]: *** [/tmp/build/perf/libperf-in.o] Error 2
make[1]: *** Waiting for unfinished jobs....
  MKDIR    /tmp/build/perf/tests/


Fixing it.
> -- 
> 2.4.11