v4.19.13 snapshot.
diff --git a/tools/testing/selftests/timers/mqueue-lat.c b/tools/testing/selftests/timers/mqueue-lat.c
new file mode 100644
index 0000000..1867db5
--- /dev/null
+++ b/tools/testing/selftests/timers/mqueue-lat.c
@@ -0,0 +1,113 @@
+/* Measure mqueue timeout latency
+ * by: john stultz (john.stultz@linaro.org)
+ * (C) Copyright Linaro 2013
+ *
+ * Inspired with permission from example test by:
+ * Romain Francoise <romain@orebokech.com>
+ * Licensed under the GPLv2
+ *
+ * To build:
+ * $ gcc mqueue-lat.c -o mqueue-lat -lrt
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <string.h>
+#include <signal.h>
+#include <errno.h>
+#include <mqueue.h>
+#include "../kselftest.h"
+
+#define NSEC_PER_SEC 1000000000ULL
+
+#define TARGET_TIMEOUT 100000000 /* 100ms in nanoseconds */
+#define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */
+
+
+long long timespec_sub(struct timespec a, struct timespec b)
+{
+ long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
+
+ ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
+ return ret;
+}
+
+struct timespec timespec_add(struct timespec ts, unsigned long long ns)
+{
+ ts.tv_nsec += ns;
+ while (ts.tv_nsec >= NSEC_PER_SEC) {
+ ts.tv_nsec -= NSEC_PER_SEC;
+ ts.tv_sec++;
+ }
+ return ts;
+}
+
+int mqueue_lat_test(void)
+{
+
+ mqd_t q;
+ struct mq_attr attr;
+ struct timespec start, end, now, target;
+ int i, count, ret;
+
+ q = mq_open("/foo", O_CREAT | O_RDONLY, 0666, NULL);
+ if (q < 0) {
+ perror("mq_open");
+ return -1;
+ }
+ mq_getattr(q, &attr);
+
+
+ count = 100;
+ clock_gettime(CLOCK_MONOTONIC, &start);
+
+ for (i = 0; i < count; i++) {
+ char buf[attr.mq_msgsize];
+
+ clock_gettime(CLOCK_REALTIME, &now);
+ target = now;
+ target = timespec_add(now, TARGET_TIMEOUT); /* 100ms */
+
+ ret = mq_timedreceive(q, buf, sizeof(buf), NULL, &target);
+ if (ret < 0 && errno != ETIMEDOUT) {
+ perror("mq_timedreceive");
+ return -1;
+ }
+ }
+ clock_gettime(CLOCK_MONOTONIC, &end);
+
+ mq_close(q);
+
+ if ((timespec_sub(start, end)/count) > TARGET_TIMEOUT + UNRESONABLE_LATENCY)
+ return -1;
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ int ret;
+
+ printf("Mqueue latency : ");
+
+ ret = mqueue_lat_test();
+ if (ret < 0) {
+ printf("[FAILED]\n");
+ return ksft_exit_fail();
+ }
+ printf("[OK]\n");
+ return ksft_exit_pass();
+}