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 <[e-mail]>
Signed-off-by: Luis Chamberlain <[e-mail]>
Reviewed-by: Muhammad Usama Anjum <[e-mail]>
Tested-by:Muhammad Usama Anjum <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

Documentation/dev-tools/kselftest.rst

···
 
 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
 ===================
 

tools/testing/selftests/kselftest/runner.sh

···
 export per_test_logging=
 
 # Defaults for "settings" file fields:
-# "timeout" how many seconds to let each test run before failing.
+# "timeout" how many seconds to let each test run before running
+# over our soft timeout limit.
 export kselftest_default_timeout=45
 
 # There isn't a shell-agnostic way to find the path of a sourced file,
···
 			value=$(echo "$line" | cut -d= -f2-)
 			eval "kselftest_$field"="$value"
 		done < "$settings"
+	fi
+
+	# Command line timeout overrides the settings file
+	if [ -n "$kselftest_override_timeout" ]; then
+		kselftest_timeout="$kselftest_override_timeout"
+		echo "# overriding timeout to $kselftest_timeout" >> "$logfile"
+	else
+		echo "# timeout set to $kselftest_timeout" >> "$logfile"
 	fi
 
 	TEST_HDR_MSG="selftests: $DIR: $BASENAME_TEST"

tools/testing/selftests/run_kselftest.sh

···
   -l | --list			List the available collection:test entries
   -d | --dry-run		Don't actually run any tests
   -h | --help			Show this usage info
+  -o | --override-timeout	Number of seconds after which we timeout
 EOF
 	exit $1
 }
···
 COLLECTIONS=""
 TESTS=""
 dryrun=""
+kselftest_override_timeout=""
 while true; do
 	case "$1" in
 		-s | --summary)
···
 		-d | --dry-run)
 			dryrun="echo"
 			shift ;;
+		-o | --override-timeout)
+			kselftest_override_timeout="$2"
+			shift 2 ;;
 		-h | --help)
 			usage 0 ;;
 		"")