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Subject[PATCH 11/16] perf unwind: Call unwind__prepare_access for forked thread
Date
From: Jiri Olsa <jolsa@kernel.org>

Currently we call unwind__prepare_access for map event. In case we
report fork event the thread inherits its parent's maps and
unwind__prepare_access is never called for the thread.

This causes unwind__get_entries seeing uninitialized
unwind_libunwind_ops and thus returning no callchain.

Adding unwind__prepare_access calls for fork even processing.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1467634583-29147-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/map.c | 9 ++++++++-
tools/perf/util/map.h | 2 +-
tools/perf/util/thread.c | 37 +++++++++++++++++++++++++++++++++++--
3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index b19bcd3b7128..b39b12a1208d 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -15,6 +15,7 @@
#include "debug.h"
#include "machine.h"
#include <linux/string.h>
+#include "unwind.h"

static void __maps__insert(struct maps *maps, struct map *map);

@@ -744,9 +745,10 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
/*
* XXX This should not really _copy_ te maps, but refcount them.
*/
-int map_groups__clone(struct map_groups *mg,
+int map_groups__clone(struct thread *thread,
struct map_groups *parent, enum map_type type)
{
+ struct map_groups *mg = thread->mg;
int err = -ENOMEM;
struct map *map;
struct maps *maps = &parent->maps[type];
@@ -757,6 +759,11 @@ int map_groups__clone(struct map_groups *mg,
struct map *new = map__clone(map);
if (new == NULL)
goto out_unlock;
+
+ err = unwind__prepare_access(thread, new, NULL);
+ if (err)
+ goto out_unlock;
+
map_groups__insert(mg, new);
map__put(new);
}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 7309d64ce39e..d83396ceecba 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -194,7 +194,7 @@ struct symbol *maps__find_symbol_by_name(struct maps *maps, const char *name,
struct map **mapp, symbol_filter_t filter);
void map_groups__init(struct map_groups *mg, struct machine *machine);
void map_groups__exit(struct map_groups *mg);
-int map_groups__clone(struct map_groups *mg,
+int map_groups__clone(struct thread *thread,
struct map_groups *parent, enum map_type type);
size_t map_groups__fprintf(struct map_groups *mg, FILE *fp);

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 2439b122a4e4..8b10a55410a2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -212,6 +212,39 @@ int thread__insert_map(struct thread *thread, struct map *map)
return 0;
}

+static int __thread__prepare_access(struct thread *thread)
+{
+ bool initialized = false;
+ int i, err = 0;
+
+ for (i = 0; i < MAP__NR_TYPES; ++i) {
+ struct maps *maps = &thread->mg->maps[i];
+ struct map *map;
+
+ pthread_rwlock_rdlock(&maps->lock);
+
+ for (map = maps__first(maps); map; map = map__next(map)) {
+ err = unwind__prepare_access(thread, map, &initialized);
+ if (err || initialized)
+ break;
+ }
+
+ pthread_rwlock_unlock(&maps->lock);
+ }
+
+ return err;
+}
+
+static int thread__prepare_access(struct thread *thread)
+{
+ int err = 0;
+
+ if (symbol_conf.use_callchain)
+ err = __thread__prepare_access(thread);
+
+ return err;
+}
+
static int thread__clone_map_groups(struct thread *thread,
struct thread *parent)
{
@@ -219,7 +252,7 @@ static int thread__clone_map_groups(struct thread *thread,

/* This is new thread, we share map groups for process. */
if (thread->pid_ == parent->pid_)
- return 0;
+ return thread__prepare_access(thread);

if (thread->mg == parent->mg) {
pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
@@ -229,7 +262,7 @@ static int thread__clone_map_groups(struct thread *thread,

/* But this one is new process, copy maps. */
for (i = 0; i < MAP__NR_TYPES; ++i)
- if (map_groups__clone(thread->mg, parent->mg, i) < 0)
+ if (map_groups__clone(thread, parent->mg, i) < 0)
return -ENOMEM;

return 0;
--
2.7.4
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