[PATCH v2 3/3] mm: slub: test: Use the kunit_get_current_test() function

[David Gow <davidgow@google.com>]

Use the newly-added function kunit_get_current_test() instead of
accessing current->kunit_test directly. This function uses a static key
to return more quickly when KUnit is enabled, but no tests are actively
running. There should therefore be a negligible performance impact to
enabling the slub KUnit tests.

Other than the performance improvement, this should be a no-op.

Cc: Oliver Glitta <glittao@gmail.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Gow <davidgow@google.com>
---

This is intended as an example use of the new function. Other users
(such as KASAN) will be updated separately, as there would otherwise be
conflicts.

Assuming there are no objections, we'll take this whole series via the
kselftest/kunit tree.

There was no v1 of this patch. v1 of the series can be found here:
https://lore.kernel.org/linux-kselftest/20221021072854.333010-1-davidgow@google.com/T/#u

---
 lib/slub_kunit.c | 1 +
 mm/slub.c        | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
index 7a0564d7cb7a..8fd19c8301ad 100644
--- a/lib/slub_kunit.c
+++ b/lib/slub_kunit.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <kunit/test.h>
+#include <kunit/test-bug.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/module.h>
diff --git a/mm/slub.c b/mm/slub.c
index 157527d7101b..15d10d250ef2 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -39,6 +39,7 @@
 #include <linux/memcontrol.h>
 #include <linux/random.h>
 #include <kunit/test.h>
+#include <kunit/test-bug.h>
 #include <linux/sort.h>
 
 #include <linux/debugfs.h>
@@ -603,10 +604,10 @@ static bool slab_add_kunit_errors(void)
 {
 	struct kunit_resource *resource;
 
-	if (likely(!current->kunit_test))
+	if (likely(!kunit_get_current_test()))
 		return false;
 
-	resource = kunit_find_named_resource(current->kunit_test, "slab_errors");
+	resource = kunit_find_named_resource(kunit_get_current_test(), "slab_errors");
 	if (!resource)
 		return false;
 
-- 
2.38.0.135.g90850a2211-goog