ktest: Add option REBOOT_SUCCESS_LINE to stop waiting after a reboot

When ktest.pl reboots, it will usuall wait SLEEP_TIME seconds of idle
console before starting the next test. By setting the
REBOOT_SUCCESS_LINE, ktest will not wait SLEEP_TIME when it detects the
line while rebooting to a new kernel.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/tools/testing/ktest/sample.conf b/tools/testing/ktest/sample.conf
index b3e0dc1..67bc4e0 100644
--- a/tools/testing/ktest/sample.conf
+++ b/tools/testing/ktest/sample.conf
@@ -423,6 +423,14 @@
 # (default "login:")
 #SUCCESS_LINE = login:
 
+# To speed up between reboots, defining a line that the
+# default kernel produces that represents that the default
+# kernel has successfully booted and can be used to pass
+# a new test kernel to it. Otherwise ktest.pl will wait till
+# SLEEP_TIME to continue.
+# (default undefined)
+#REBOOT_SUCCESS_LINE = login:
+
 # In case the console constantly fills the screen, having
 # a specified time to stop the test after success is recommended.
 # (in seconds)
@@ -488,6 +496,8 @@
 # another test. If a reboot to the reliable kernel happens,
 # we wait SLEEP_TIME for the console to stop producing output
 # before starting the next test.
+#
+# You can speed up reboot times even more by setting REBOOT_SUCCESS_LINE.
 # (default 60)
 #SLEEP_TIME = 60