selftests: allow runners to override the timeout

The default timeout for selftests tests is 45 seconds. Although
we already have 13 settings for tests of about 96 sefltests which
use a timeout greater than this, we want to try to avoid encouraging
more tests to forcing a higher test timeout as selftests strives to
run all tests quickly. Selftests also uses the timeout as a non-fatal
error. Only tests runners which have control over a system would know
if to treat a timeout as fatal or not.

To help with all this:

  o Enhance documentation to avoid future increases of insane timeouts
  o Add the option to allow overriding the default timeout with test
    runners with a command line option

Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Tested-by:Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst
index 12b575b76b20..dd214af7b7ff 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -168,6 +168,28 @@ the `-t` option for specific single tests. Either can be used multiple times::
 
 For other features see the script usage output, seen with the `-h` option.
 
+Timeout for selftests
+=====================
+
+Selftests are designed to be quick and so a default timeout is used of 45
+seconds for each test. Tests can override the default timeout by adding
+a settings file in their directory and set a timeout variable there to the
+configured a desired upper timeout for the test. Only a few tests override
+the timeout with a value higher than 45 seconds, selftests strives to keep
+it that way. Timeouts in selftests are not considered fatal because the
+system under which a test runs may change and this can also modify the
+expected time it takes to run a test. If you have control over the systems
+which will run the tests you can configure a test runner on those systems to
+use a greater or lower timeout on the command line as with the `-o` or
+the `--override-timeout` argument. For example to use 165 seconds instead
+one would use:
+
+   $ ./run_kselftest.sh --override-timeout 165
+
+You can look at the TAP output to see if you ran into the timeout. Test
+runners which know a test must run under a specific time can then optionally
+treat these timeouts then as fatal.
+
 Packaging selftests
 ===================