tests/perf_pmu: Handle CPU hotplug failures better

CPU hotplug, especially CPU0, can be flaky on commodity hardware.

To improve test reliability and reponse times when testing larger runs we
need to handle those cases better.

Handle failures to off-line a CPU by immediately skipping the test, and
failures to on-line a CPU by immediately rebooting the machine.

This patch includes igt_sysrq_reboot implementation from Chris Wilson.

v2: Halt by default, reboot if env variable IGT_REBOOT_ON_FATAL_ERROR is
    set. (Petri Latvala)

v3: Add missign docs and update stale comment. (Petri Latvala)

v4: Use pause instead of sleep. (Chris Wilson)
v5: Newlines! (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Petri Latvala <petri.latvala@intel.com>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/igt_core.c b/lib/igt_core.c
index c292343d..e52b806b 100644
--- a/lib/igt_core.c
+++ b/lib/igt_core.c
@@ -70,6 +70,7 @@
 #include "igt_core.h"
 #include "igt_aux.h"
 #include "igt_sysfs.h"
+#include "igt_sysrq.h"
 #include "igt_rc.h"
 
 #define UNW_LOCAL_ONLY
@@ -1137,6 +1138,28 @@ void igt_fail(int exitcode)
 }
 
 /**
+ * igt_fatal_error: Stop test execution on fatal errors
+ *
+ * Stop test execution or optionally, if the IGT_REBOOT_ON_FATAL_ERROR
+ * environment variable is set, reboot the machine.
+ *
+ * Since out test runner (piglit) does support fatal test exit codes, we
+ * implement the default behaviour by waiting endlessly.
+ */
+void  __attribute__((noreturn)) igt_fatal_error(void)
+{
+	if (igt_check_boolean_env_var("IGT_REBOOT_ON_FATAL_ERROR", false)) {
+		igt_warn("FATAL ERROR - REBOOTING\n");
+		igt_sysrq_reboot();
+	} else {
+		igt_warn("FATAL ERROR\n");
+		for (;;)
+			pause();
+	}
+}
+
+
+/**
  * igt_can_fail:
  *
  * Returns true if called from either an #igt_fixture, #igt_subtest or a