kunit: Make filter parameters configurable via Kconfig

Enable the preset of filter parameters from kconfig options, similar to
how other KUnit configuration parameters are handled already.
This is useful to run a subset of tests even if the cmdline is not
readily modifyable.

Link: https://lore.kernel.org/r/20251106-kunit-filter-kconfig-v1-1-d723fb7ac221@linutronix.de
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: t-8ch

lib/kunit/Kconfig

@@ -93,6 +93,30 @@ config KUNIT_AUTORUN_ENABLED
 	  In most cases this should be left as Y. Only if additional opt-in
 	  behavior is needed should this be set to N.
 
+config KUNIT_DEFAULT_FILTER_GLOB
+	string "Default value of the filter_glob module parameter"
+	help
+	  Sets the default value of kunit.filter_glob. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
+config KUNIT_DEFAULT_FILTER
+	string "Default value of the filter module parameter"
+	help
+	  Sets the default value of kunit.filter. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
+config KUNIT_DEFAULT_FILTER_ACTION
+	string "Default value of the filter_action module parameter"
+	help
+	  Sets the default value of kunit.filter_action. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
 config KUNIT_DEFAULT_TIMEOUT
 	int "Default value of the timeout module parameter"
 	default 300

lib/kunit/executor.c

@@ -45,9 +45,11 @@ bool kunit_autorun(void)
 	return autorun_param;
 }
 
-static char *filter_glob_param;
-static char *filter_param;
-static char *filter_action_param;
+#define PARAM_FROM_CONFIG(config) (config[0] ? config : NULL)
+
+static char *filter_glob_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER_GLOB);
+static char *filter_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER);
+static char *filter_action_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER_ACTION);
 
 module_param_named(filter_glob, filter_glob_param, charp, 0600);
 MODULE_PARM_DESC(filter_glob,