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

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Date:	Mon,  4 Jul 2016 14:16:22 +0200
From:	Jiri Olsa <jolsa@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...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: [PATCH 3/4] perf tools: Add initialized arg into unwind__prepare_access

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;
 }
-- 
2.4.11