perf bench: Fix 2 memory sanitizer warnings

Memory sanitizer warns if a write is performed where the memory being
read for the write is uninitialized. Avoid this warning by initializing
the memory.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200912053725.1405857-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/bench/sched-messaging.c b/tools/perf/bench/sched-messaging.c
index 71d830d..cecce93 100644 (file)
--- a/tools/perf/bench/sched-messaging.c
+++ b/tools/perf/bench/sched-messaging.c
@@ -66,11 +66,10 @@ static void fdpair(int fds[2])
 /* Block until we're ready to go */
 static void ready(int ready_out, int wakefd)
 {
-       char dummy;
        struct pollfd pollfd = { .fd = wakefd, .events = POLLIN };
 
        /* Tell them we're ready. */
-       if (write(ready_out, &dummy, 1) != 1)
+       if (write(ready_out, "R", 1) != 1)
                err(EXIT_FAILURE, "CLIENT: ready write");
 
        /* Wait for "GO" signal */
@@ -85,6 +84,7 @@ static void *sender(struct sender_context *ctx)
        unsigned int i, j;
 
        ready(ctx->ready_out, ctx->wakefd);
+       memset(data, 'S', sizeof(data));
 
        /* Now pump to every receiver. */
        for (i = 0; i < nr_loops; i++) {