[PATCH v1 1/1] perf unwind: Fix map reference counts

[PATCH v1 1/1] perf unwind: Fix map reference counts

[Ian Rogers]

The result of thread__find_map is the map in the passed in
addr_location. Calling addr_location__exit puts that map and so copies
need to do a map__get. Add in the corresponding map__puts.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/unwind-libunwind-local.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/unwind-libunwind-local.c
index 36bf5100bad2..9cb82d7c7dc7 100644
--- a/tools/perf/util/unwind-libunwind-local.c
+++ b/tools/perf/util/unwind-libunwind-local.c
@@ -419,7 +419,8 @@ static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
 	struct map *ret;
 
 	addr_location__init(&al);
-	ret = thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
+	thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
+	ret = map__get(al.map);
 	addr_location__exit(&al);
 	return ret;
 }
@@ -476,11 +477,11 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
 
 		memset(&di, 0, sizeof(di));
 		if (dwarf_find_debug_frame(0, &di, ip, base, symfile, start, map__end(map)))
-			return dwarf_search_unwind_table(as, ip, &di, pi,
-							 need_unwind_info, arg);
+			ret = dwarf_search_unwind_table(as, ip, &di, pi,
+							need_unwind_info, arg);
 	}
 #endif
-
+	map__put(map);
 	return ret;
 }
 
@@ -539,7 +540,7 @@ static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
 
 	size = dso__data_read_addr(dso, map, ui->machine,
 				   addr, (u8 *) data, sizeof(*data));
-
+	map__put(map);
 	return !(size == sizeof(*data));
 }
 
-- 
2.41.0.162.gfafddb0af9-goog

Re: [PATCH v1 1/1] perf unwind: Fix map reference counts

[Namhyung Kim]

On Wed, Jun 21, 2023 at 10:10 PM Ian Rogers <irogers@google.com> wrote:
>
> The result of thread__find_map is the map in the passed in
> addr_location. Calling addr_location__exit puts that map and so copies
> need to do a map__get. Add in the corresponding map__puts.

It also needs map__put() when map__dso() returns NULL.

Thanks,
Namhyung


>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/unwind-libunwind-local.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/unwind-libunwind-local.c
> index 36bf5100bad2..9cb82d7c7dc7 100644
> --- a/tools/perf/util/unwind-libunwind-local.c
> +++ b/tools/perf/util/unwind-libunwind-local.c
> @@ -419,7 +419,8 @@ static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
>         struct map *ret;
>
>         addr_location__init(&al);
> -       ret = thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
> +       thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
> +       ret = map__get(al.map);
>         addr_location__exit(&al);
>         return ret;
>  }
> @@ -476,11 +477,11 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
>
>                 memset(&di, 0, sizeof(di));
>                 if (dwarf_find_debug_frame(0, &di, ip, base, symfile, start, map__end(map)))
> -                       return dwarf_search_unwind_table(as, ip, &di, pi,
> -                                                        need_unwind_info, arg);
> +                       ret = dwarf_search_unwind_table(as, ip, &di, pi,
> +                                                       need_unwind_info, arg);
>         }
>  #endif
> -
> +       map__put(map);
>         return ret;
>  }
>
> @@ -539,7 +540,7 @@ static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
>
>         size = dso__data_read_addr(dso, map, ui->machine,
>                                    addr, (u8 *) data, sizeof(*data));
> -
> +       map__put(map);
>         return !(size == sizeof(*data));
>  }
>
> --
> 2.41.0.162.gfafddb0af9-goog
>