[PATCH][next] libperf: Use struct_size() helper

["Gustavo A. R. Silva" <gustavoars@kernel.org>]

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes. Also, remove unnecessary
variable _size_.

This code was detected with the help of Coccinelle and, audited and
fixed manually.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 tools/lib/perf/threadmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/perf/threadmap.c b/tools/lib/perf/threadmap.c
index e92c368b0a6c..86d9dabd7fe5 100644
--- a/tools/lib/perf/threadmap.c
+++ b/tools/lib/perf/threadmap.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <asm/bug.h>
 #include <stdio.h>
+#include <linux/overflow.h>
 
 static void perf_thread_map__reset(struct perf_thread_map *map, int start, int nr)
 {
@@ -17,10 +18,9 @@ static void perf_thread_map__reset(struct perf_thread_map *map, int start, int n
 
 struct perf_thread_map *perf_thread_map__realloc(struct perf_thread_map *map, int nr)
 {
-	size_t size = sizeof(*map) + sizeof(map->map[0]) * nr;
 	int start = map ? map->nr : 0;
 
-	map = realloc(map, size);
+	map = realloc(map, struct_size(map, map, nr));
 	/*
 	 * We only realloc to add more items, let's reset new items.
 	 */
-- 
2.27.0