lib: Break poll loop to check for a missed signal

If our parent dies, so should we. Our parent should kill us before it
exits, but just in case we escape, wake up periodically to check upon
our parent.

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

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index 447e4f08..2eb71449 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -359,6 +359,7 @@ hang_detector_process(pid_t pid, dev_t rdev)
 	struct udev_monitor *mon =
 		udev_monitor_new_from_netlink(udev_new(), "kernel");
 	struct pollfd pfd;
+	int ret;
 
 	udev_monitor_filter_add_match_subsystem_devtype(mon, "drm", NULL);
 	udev_monitor_enable_receiving(mon);
@@ -366,14 +367,19 @@ hang_detector_process(pid_t pid, dev_t rdev)
 	pfd.fd = udev_monitor_get_fd(mon);
 	pfd.events = POLLIN;
 
-	while (poll(&pfd, 1, -1) > 0) {
+	while ((ret = poll(&pfd, 1, 2000)) >= 0) {
 		struct udev_device *dev;
 		dev_t devnum;
 
-		if (kill(pid, 0)) /* Parent has died, so must we. */
+		if (kill(pid, 0)) { /* Parent has died, so must we. */
+			igt_warn("Parent died without killing its children (%s)\n",
+				 __func__);
 			break;
+		}
 
-		dev = udev_monitor_receive_device(mon);
+		dev = NULL;
+		if (ret > 0)
+			dev = udev_monitor_receive_device(mon);
 		if (dev == NULL)
 			continue;