lib: Force global reset + uevents for hang detector

The hang detector relies on a uevent for notification and aborting the
test. As proposed, fine-grained resets may not produce a global uevent
and so this hang detection becomes void. As we don't expect any hang, we
can just reduce the reset to only a global + uevent and so maintain
functionality, and switch back to fine-grained resets afterwards.

Note that any test that requires testing fine-grained resets should
ensure that they are enabled first as igt may leave the global
parameters in an inconsistent state.

v2: Restore fine-grained resets for explict igt_allow_hang()

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index f76e55d5..eb563f72 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -58,6 +58,7 @@
 #include "igt_debugfs.h"
 #include "igt_gt.h"
 #include "igt_rand.h"
+#include "igt_sysfs.h"
 #include "config.h"
 #include "intel_reg.h"
 #include "ioctl_wrappers.h"
@@ -451,6 +452,15 @@ void igt_fork_hang_detector(int fd)
 
 	igt_assert(fstat(fd, &st) == 0);
 
+	/*
+	 * Disable per-engine reset to force an error uevent. We don't
+	 * expect to get any hangs whilst the detector is enabled (if we do
+	 * they are a test failure!) and so the loss of per-engine reset
+	 * functionality is not an issue.
+	 */
+	igt_assert(igt_sysfs_set_parameter
+		   (fd, "reset", "%d", 1 /* only global reset */));
+
 	signal(SIGIO, sig_abort);
 	igt_fork_helper(&hang_detector)
 		hang_detector_process(getppid(), st.st_rdev);