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From:   glittao@gmail.com
To:     brendanhiggins@google.com, cl@linux.com, penberg@kernel.org,
        rientjes@google.com, iamjoonsoo.kim@lge.com,
        akpm@linux-foundation.org, vbabka@suse.cz
Cc:     linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        kunit-dev@googlegroups.com, linux-mm@kvack.org, elver@google.com,
        dlatypov@google.com, Oliver Glitta <glittao@gmail.com>
Subject: [PATCH v4 1/3] kunit: make test->lock irq safe
Date:   Tue, 13 Apr 2021 12:07:45 +0200
Message-Id: <20210413100747.4921-1-glittao@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Vlastimil Babka <vbabka@suse.cz>

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 <vbabka@suse.cz>
Signed-off-by: Oliver Glitta <glittao@gmail.com>
---
 include/kunit/test.h |  5 +++--
 lib/kunit/test.c     | 18 +++++++++++-------
 2 files changed, 14 insertions(+), 9 deletions(-)

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 ec9494e914ef..2c62eeb45b82 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -442,6 +442,7 @@ int kunit_add_resource(struct kunit *test,
 		       void *data)
 {
 	int ret = 0;
+	unsigned long flags;
 
 	res->free = free;
 	kref_init(&res->refcount);
@@ -454,10 +455,10 @@ 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;
 }
@@ -515,9 +516,11 @@ 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);
@@ -597,6 +600,7 @@ 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
@@ -608,9 +612,9 @@ 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,
@@ -621,7 +625,7 @@ 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);
 	}
 #if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
-- 
2.31.1.272.g89b43f80a5