[igt-dev] [PATCH i-g-t] tests/perf_pmu: Avoid off-lining all CPUs

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Bail out from the cpu-hotplug test if we failed to bring a CPU back
online.

This still leaves the machine in a quite bad state, but at least it
avoids hard hanging it.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 tests/perf_pmu.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 7fab73e22c2d..a334d3b5770e 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -965,6 +965,7 @@ static void cpu_hotplug(int gem_fd)
 	int link[2];
 	int fd, ret;
 	int cur = 0;
+	char buf;
 
 	igt_require(cpu0_hotplug_support());
 
@@ -1012,7 +1013,15 @@ static void cpu_hotplug(int gem_fd)
 			/* Offline followed by online a CPU. */
 			igt_assert_eq(write(cpufd, "0", 2), 2);
 			usleep(1e6);
-			igt_assert_eq(write(cpufd, "1", 2), 2);
+			ret = write(cpufd, "1", 2);
+			if (ret < 0) {
+				/*
+				 * Abort the test if we failed to bring a CPU
+				 * back online.
+				 */
+				igt_assert_eq(write(link[1], "s", 1), 1);
+				break;
+			}
 
 			close(cpufd);
 			cpu++;
@@ -1026,7 +1035,6 @@ static void cpu_hotplug(int gem_fd)
 	 * until the CPU core shuffler finishes one loop.
 	 */
 	for (;;) {
-		char buf;
 		int ret2;
 
 		usleep(500e3);
@@ -1053,6 +1061,9 @@ static void cpu_hotplug(int gem_fd)
 	close(fd);
 	close(link[0]);
 
+	/* Skip if child signals a problem with bringing a CPU back online. */
+	igt_skip_on(buf == 's');
+
 	assert_within_epsilon(val, ts[1] - ts[0], tolerance);
 }
 
-- 
2.14.1