[v5,1/3] kunit: make test->lock irq safe

Commit Message

Oliver Glitta May 11, 2021, 3:07 p.m. UTC

From: Vlastimil Babka <[e-mail]>

The upcoming SLUB kunit test will be calling kunit_find_named_resource() from
a context with disabled interrupts. That means kunit's test->lock needs to be
IRQ safe to avoid potential deadlocks and lockdep splats.

This patch therefore changes the test->lock usage to spin_lock_irqsave()
and spin_unlock_irqrestore().

Signed-off-by: Vlastimil Babka <[e-mail]>
Signed-off-by: Oliver Glitta <[e-mail]>
---
Changes since v4
Rebased whole series on 5.13-rc1

 include/kunit/test.h |  5 +++--
 lib/kunit/test.c     | 18 +++++++++++-------
 2 files changed, 14 insertions(+), 9 deletions(-)

--
2.31.1.272.g89b43f80a5

Comments

Vlastimil Babka May 12, 2021, 10:28 a.m. UTC | #1

On 5/11/21 5:07 PM, [e-mail] wrote:
> From: Vlastimil Babka <[e-mail]>
> 
> The upcoming SLUB kunit test will be calling kunit_find_named_resource() from
> a context with disabled interrupts. That means kunit's test->lock needs to be
> IRQ safe to avoid potential deadlocks and lockdep splats.
> 
> This patch therefore changes the test->lock usage to spin_lock_irqsave()
> and spin_unlock_irqrestore().
> 
> Signed-off-by: Vlastimil Babka <[e-mail]>
> Signed-off-by: Oliver Glitta <[e-mail]>

Note v4 had

Reviewed-by: Brendan Higgins <[e-mail]>

and it's unchanged AFAIK.

Patch

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 49601c4b98b8..524d4789af22 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -515,8 +515,9 @@  kunit_find_resource(struct kunit *test,
 		    void *match_data)
 {
 	struct kunit_resource *res, *found = NULL;
+	unsigned long flags;

-	spin_lock(&test->lock);
+	spin_lock_irqsave(&test->lock, flags);

 	list_for_each_entry_reverse(res, &test->resources, node) {
 		if (match(test, res, (void *)match_data)) {
@@ -526,7 +527,7 @@  kunit_find_resource(struct kunit *test,
 		}
 	}

-	spin_unlock(&test->lock);
+	spin_unlock_irqrestore(&test->lock, flags);

 	return found;
 }
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 2f6cc0123232..45f068864d76 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -475,6 +475,7 @@  int kunit_add_resource(struct kunit *test,
 		       void *data)
 {
 	int ret = 0;
+	unsigned long flags;

 	res->free = free;
 	kref_init(&res->refcount);
@@ -487,10 +488,10 @@  int kunit_add_resource(struct kunit *test,
 		res->data = data;
 	}

-	spin_lock(&test->lock);
+	spin_lock_irqsave(&test->lock, flags);
 	list_add_tail(&res->node, &test->resources);
 	/* refcount for list is established by kref_init() */
-	spin_unlock(&test->lock);
+	spin_unlock_irqrestore(&test->lock, flags);

 	return ret;
 }
@@ -548,9 +549,11 @@  EXPORT_SYMBOL_GPL(kunit_alloc_and_get_resource);

 void kunit_remove_resource(struct kunit *test, struct kunit_resource *res)
 {
-	spin_lock(&test->lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&test->lock, flags);
 	list_del(&res->node);
-	spin_unlock(&test->lock);
+	spin_unlock_irqrestore(&test->lock, flags);
 	kunit_put_resource(res);
 }
 EXPORT_SYMBOL_GPL(kunit_remove_resource);
@@ -630,6 +633,7 @@  EXPORT_SYMBOL_GPL(kunit_kfree);
 void kunit_cleanup(struct kunit *test)
 {
 	struct kunit_resource *res;
+	unsigned long flags;

 	/*
 	 * test->resources is a stack - each allocation must be freed in the
@@ -641,9 +645,9 @@  void kunit_cleanup(struct kunit *test)
 	 * protect against the current node being deleted, not the next.
 	 */
 	while (true) {
-		spin_lock(&test->lock);
+		spin_lock_irqsave(&test->lock, flags);
 		if (list_empty(&test->resources)) {
-			spin_unlock(&test->lock);
+			spin_unlock_irqrestore(&test->lock, flags);
 			break;
 		}
 		res = list_last_entry(&test->resources,
@@ -654,7 +658,7 @@  void kunit_cleanup(struct kunit *test)
 		 * resource, and this can't happen if the test->lock
 		 * is held.
 		 */
-		spin_unlock(&test->lock);
+		spin_unlock_irqrestore(&test->lock, flags);
 		kunit_remove_resource(test, res);
 	}
 	current->kunit_test = NULL;