igt/gem_softpin: Repeat tests with signal interruptions

For the long running tests probing error conditions, throwing in the
signal interruptions is a good idea.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

lib/igt_core.c

@@ -396,6 +396,23 @@ error:
 	return -errno;
 }
 
+#define MSEC_PER_SEC (1000)
+#define USEC_PER_SEC (1000*MSEC_PER_SEC)
+#define NSEC_PER_SEC (1000*USEC_PER_SEC)
+uint64_t igt_nsec_elapsed(struct timespec *start)
+{
+	struct timespec now;
+
+	gettime(&now);
+	if ((start->tv_sec | start->tv_nsec) == 0) {
+		*start = now;
+		return 0;
+	}
+
+	return ((now.tv_nsec - start->tv_nsec) +
+		NSEC_PER_SEC*(now.tv_sec - start->tv_sec));
+}
+
 bool __igt_fixture(void)
 {
 	assert(!in_fixture);

lib/igt_core.h

@@ -32,6 +32,7 @@
 
 #include <setjmp.h>
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -775,6 +776,40 @@ extern enum igt_log_level igt_log_level;
 void igt_set_timeout(unsigned int seconds,
 		     const char *op);
 
+/**
+ * igt_nsec_elapsed:
+ * @start: measure from this point in time
+ *
+ * Reports the difference in the monotonic clock from the start time
+ * in nanoseconds. On the first invocation, start should be zeroed and will
+ * be set by the call.
+ *
+ * Typical use would be:
+ *
+ * igt_subtest("test") {
+ * 	struct timespec start = {};
+ * 	while (igt_nsec_elapsed(&start) < test_timeout_ns)
+ *	 	do_test();
+ * }
+ *
+ * A handy approximation is to use nsec >> 30 to convert to seconds,
+ * nsec >> 20 to convert to milliseconds - the error is about 8%, acceptable
+ * for test run times.
+ */
+uint64_t igt_nsec_elapsed(struct timespec *start);
+
+/**
+ * igt_seconds_elapsed:
+ * @start: measure from this point in time
+ *
+ * A wrapper around igt_nsec_elapsed that reports the approximate (8% error)
+ * number of seconds since the start point.
+ */
+static inline uint32_t igt_seconds_elapsed(struct timespec *start)
+{
+	return igt_nsec_elapsed(start) >> 30;
+}
+
 void igt_reset_timeout(void);
 
 FILE *__igt_fopen_data(const char* igt_srcdir, const char* igt_datadir,