kunit: add ability to run tests after boot using debugfs

Add functionality to run built-in tests after boot by writing to a
debugfs file.

Add a new debugfs file labeled "run" for each test suite to use for
this purpose.

As an example, write to the file using the following:

echo "any string" > /sys/kernel/debugfs/kunit/<testsuite>/run

This will trigger the test suite to run and will print results to the
kernel log.

To guard against running tests concurrently with this feature, add a
mutex lock around running kunit. This supports the current practice of
not allowing tests to be run concurrently on the same kernel.

This new functionality could be used to design a parameter
injection feature in the future.

Fixed up merge conflict duing rebase to Linux 6.7-rc6
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 6b60d85ce108..088489856db8 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/mutex.h>
 #include <linux/panic.h>
 #include <linux/sched/debug.h>
 #include <linux/sched.h>
@@ -22,6 +23,8 @@
 #include "string-stream.h"
 #include "try-catch-impl.h"
 
+static DEFINE_MUTEX(kunit_run_lock);
+
 /*
  * Hook to fail the current test and print an error message to the log.
  */
@@ -692,6 +695,7 @@ static void kunit_init_suite(struct kunit_suite *suite)
 	kunit_debugfs_create_suite(suite);
 	suite->status_comment[0] = '\0';
 	suite->suite_init_err = 0;
+	string_stream_clear(suite->log);
 }
 
 bool kunit_enabled(void)
@@ -710,6 +714,11 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
 
 	kunit_suite_counter = 1;
 
+	/* Use mutex lock to guard against running tests concurrently. */
+	if (mutex_lock_interruptible(&kunit_run_lock)) {
+		pr_err("kunit: test interrupted\n");
+		return -EINTR;
+	}
 	static_branch_inc(&kunit_running);
 
 	for (i = 0; i < num_suites; i++) {
@@ -718,6 +727,7 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
 	}
 
 	static_branch_dec(&kunit_running);
+	mutex_unlock(&kunit_run_lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__kunit_test_suites_init);