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Date: Thu,  1 Feb 2024 14:04:36 +0800
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Message-ID: <20240201060437.861155-2-davidgow@google.com>
Subject: [PATCH] kunit: device: Unregister the kunit_bus on shutdown
From: David Gow <davidgow@google.com>
To: Rae Moar <rmoar@google.com>, Shuah Khan <skhan@linuxfoundation.org>
Cc: David Gow <davidgow@google.com>, Matti Vaittinen <mazziesaccount@gmail.com>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Brendan Higgins <brendan.higgins@linux.dev>, 
	Maxime Ripard <mripard@kernel.org>, linux-kselftest@vger.kernel.org, 
	kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, Borah@google.com, 
	Chaitanya Kumar <chaitanya.kumar.borah@intel.com>, Saarinen@google.com, 
	Jani <jani.saarinen@intel.com>, Richard Fitzgerald <rf@opensource.cirrus.com>, 
	intel-gfx@lists.freedesktop.org
Content-Type: text/plain; charset="UTF-8"

If KUnit is built as a module, and it's unloaded, the kunit_bus is not
unregistered. This causes an error if it's then re-loaded later, as we
try to re-register the bus.

Unregister the bus and root_device on shutdown, if it looks valid.

In addition, be more specific about the value of kunit_bus_device. It
is:
- a valid struct device* if the kunit_bus initialised correctly.
- an ERR_PTR if it failed to initialise.
- NULL before initialisation and after shutdown.

Fixes: d03c720e03bd ("kunit: Add APIs for managing devices")
Signed-off-by: David Gow <davidgow@google.com>
---

This will hopefully resolve some of the issues linked to from:
https://lore.kernel.org/intel-gfx/DM4PR11MB614179CB9C387842D8E8BB40B97C2@DM4PR11MB6141.namprd11.prod.outlook.com/

---
 lib/kunit/device-impl.h |  2 ++
 lib/kunit/device.c      | 14 ++++++++++++++
 lib/kunit/test.c        |  3 +++
 3 files changed, 19 insertions(+)

diff --git a/lib/kunit/device-impl.h b/lib/kunit/device-impl.h
index 54bd55836405..5fcd48ff0f36 100644
--- a/lib/kunit/device-impl.h
+++ b/lib/kunit/device-impl.h
@@ -13,5 +13,7 @@
 
 // For internal use only -- registers the kunit_bus.
 int kunit_bus_init(void);
+// For internal use only -- unregisters the kunit_bus.
+void kunit_bus_shutdown(void);
 
 #endif //_KUNIT_DEVICE_IMPL_H
diff --git a/lib/kunit/device.c b/lib/kunit/device.c
index 074c6dd2e36a..644a38a1f5b1 100644
--- a/lib/kunit/device.c
+++ b/lib/kunit/device.c
@@ -54,6 +54,20 @@ int kunit_bus_init(void)
 	return error;
 }
 
+/* Unregister the 'kunit_bus' in case the KUnit module is unloaded. */
+void kunit_bus_shutdown(void)
+{
+	/* Make sure the bus exists before we unregister it. */
+	if (IS_ERR_OR_NULL(kunit_bus_device))
+		return;
+
+	bus_unregister(&kunit_bus_type);
+
+	root_device_unregister(kunit_bus_device);
+
+	kunit_bus_device = NULL;
+}
+
 /* Release a 'fake' KUnit device. */
 static void kunit_device_release(struct device *d)
 {
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 31a5a992e646..1d1475578515 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -928,6 +928,9 @@ static void __exit kunit_exit(void)
 #ifdef CONFIG_MODULES
 	unregister_module_notifier(&kunit_mod_nb);
 #endif
+
+	kunit_bus_shutdown();
+
 	kunit_debugfs_cleanup();
 }
 module_exit(kunit_exit);
-- 
2.43.0.429.g432eaa2c6b-goog