cyclictest: Fix tracemark output when the latency threshold is hit on ARM

on ARM I'm seeing output like:

	cyclicte-623     0....... 19619418us+: tracing_mark_write: hit latency threshold (2000 > 2097)

That's because of a format mismatch in

	tracemark("hit latency threshold (%d > %d)", diff, tracelimit);

diff is a u64 and tracelimit an int. So on ARM the string is passed in r0,
tracelimit in r1 and diff in r2+r3. vsnprintf used in tracemark only
expects two ints passed and so only uses r1 and r2 yielding the permutation
in the output.

This patch also adds a gcc attribute to tracemark that helps catching
similar bugs. In this case just adding the attribute but not touching
the call site, would result in:

	src/cyclictest/cyclictest.c: In function ‘timerthread’:
	src/cyclictest/cyclictest.c:899:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘uint64_t’ [-Wformat]

---
Hello

after some chatting with Clark and John I dropped the c99 stuff and added the
attribute annotation.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Clark Williams <clark.williams@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 686a635..c3fa60f 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -400,6 +400,7 @@ static int trace_file_exists(char *name)
 #define TRACEBUFSIZ 1024
 static __thread char tracebuf[TRACEBUFSIZ];
 
+static void tracemark(char *fmt, ...) __attribute__((format(printf, 1, 2)));
 static void tracemark(char *fmt, ...)
 {
 	va_list ap;
@@ -895,7 +896,8 @@ void *timerthread(void *param)
 
 		if (!stopped && tracelimit && (diff > tracelimit)) {
 			stopped++;
-			tracemark("hit latency threshold (%d > %d)", diff, tracelimit);
+			tracemark("hit latency threshold (%llu > %d)",
+				  (unsigned long long) diff, tracelimit);
 			tracing(0);
 			shutdown++;
 			pthread_mutex_lock(&break_thread_id_lock);