linux-kernel - [tip:perf/core] perf record: Do not put a variable sized type not at the end of a struct

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Message-ID: <tip-c9drclo52ezxmwa7qxklin2y@git.kernel.org>
Date:   Thu, 16 Feb 2017 12:02:01 -0800
From:   tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     namhyung@...nel.org, wangnan0@...wei.com, hpa@...or.com,
        tglx@...utronix.de, acme@...hat.com, linux-kernel@...r.kernel.org,
        dsahern@...il.com, jolsa@...nel.org, adrian.hunter@...el.com,
        mingo@...nel.org
Subject: [tip:perf/core] perf record: Do not put a variable sized type not
 at the end of a struct

Commit-ID:  9d6aae725454beada044179f1005c8f8c206dd6a
Gitweb:     http://git.kernel.org/tip/9d6aae725454beada044179f1005c8f8c206dd6a
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Tue, 14 Feb 2017 10:59:04 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Tue, 14 Feb 2017 15:19:19 -0300

perf record: Do not put a variable sized type not at the end of a struct

As this is a GNU extension and while harmless in this case, we can do
the same thing in a more clearer way by using an existing thread_map
constructor.

With this we avoid this while compiling with clang:

  builtin-record.c:659:21: error: field 'map' with variable sized type 'struct thread_map' not at the end of a struct or class is a GNU extension
        [-Werror,-Wgnu-variable-sized-type-not-at-end]
                  struct thread_map map;
                                    ^
  1 error generated.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-c9drclo52ezxmwa7qxklin2y@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-record.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 2ddf189..6cd6776 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -655,22 +655,23 @@ record__finish_output(struct record *rec)
 
 static int record__synthesize_workload(struct record *rec, bool tail)
 {
-	struct {
-		struct thread_map map;
-		struct thread_map_data map_data;
-	} thread_map;
+	int err;
+	struct thread_map *thread_map;
 
 	if (rec->opts.tail_synthesize != tail)
 		return 0;
 
-	thread_map.map.nr = 1;
-	thread_map.map.map[0].pid = rec->evlist->workload.pid;
-	thread_map.map.map[0].comm = NULL;
-	return perf_event__synthesize_thread_map(&rec->tool, &thread_map.map,
+	thread_map = thread_map__new_by_tid(rec->evlist->workload.pid);
+	if (thread_map == NULL)
+		return -1;
+
+	err = perf_event__synthesize_thread_map(&rec->tool, thread_map,
 						 process_synthesized_event,
 						 &rec->session->machines.host,
 						 rec->opts.sample_address,
 						 rec->opts.proc_map_timeout);
+	thread_map__put(thread_map);
+	return err;
 }
 
 static int record__synthesize(struct record *rec, bool tail);