linux-kernel - [tip:perf/urgent] perf test mmap-thread-lookup: Initialize variable to suppress memory sanitizer warning

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Date:   Sat, 13 Jul 2019 03:52:23 -0700
From:   tip-bot for Numfor Mbiziwo-Tiapo <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mbd@...com, linux-kernel@...r.kernel.org, mingo@...nel.org,
        namhyung@...nel.org, hpa@...or.com, irogers@...gle.com,
        alexander.shishkin@...ux.intel.com, songliubraving@...com,
        tglx@...utronix.de, eranian@...gle.com, jolsa@...hat.com,
        acme@...hat.com, peterz@...radead.org, nums@...gle.com
Subject: [tip:perf/urgent] perf test mmap-thread-lookup: Initialize variable
 to suppress memory sanitizer warning

Commit-ID:  4e4cf62b37da5ff45c904a3acf242ab29ed5881d
Gitweb:     https://git.kernel.org/tip/4e4cf62b37da5ff45c904a3acf242ab29ed5881d
Author:     Numfor Mbiziwo-Tiapo <nums@...gle.com>
AuthorDate: Tue, 2 Jul 2019 10:37:15 -0700
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Tue, 9 Jul 2019 09:33:54 -0300

perf test mmap-thread-lookup: Initialize variable to suppress memory sanitizer warning

Running the 'perf test' command after building perf with a memory
sanitizer causes a warning that says:

  WARNING: MemorySanitizer: use-of-uninitialized-value... in mmap-thread-lookup.c

Initializing the go variable to 0 silences this harmless warning.

Committer warning:

This was harmless, just a simple test writing whatever was at that
sizeof(int) memory area just to signal another thread blocked reading
that file created with pipe(). Initialize it tho so that we don't get
this warning.

Signed-off-by: Numfor Mbiziwo-Tiapo <nums@...gle.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Mark Drayton <mbd@...com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Song Liu <songliubraving@...com>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/r/20190702173716.181223-1-nums@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/tests/mmap-thread-lookup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/mmap-thread-lookup.c b/tools/perf/tests/mmap-thread-lookup.c
index ba87e6e8d18c..0a4301a5155c 100644
--- a/tools/perf/tests/mmap-thread-lookup.c
+++ b/tools/perf/tests/mmap-thread-lookup.c
@@ -53,7 +53,7 @@ static void *thread_fn(void *arg)
 {
 	struct thread_data *td = arg;
 	ssize_t ret;
-	int go;
+	int go = 0;
 
 	if (thread_init(td))
 		return NULL;