[PATCH v5 02/18] kunit: test: add test resource management API

[Brendan Higgins]

Create a common API for test managed resources like memory and test
objects. A lot of times a test will want to set up infrastructure to be
used in test cases; this could be anything from just wanting to allocate
some memory to setting up a driver stack; this defines facilities for
creating "test resources" which are managed by the test infrastructure
and are automatically cleaned up at the conclusion of the test.

Signed-off-by: Brendan Higgins <brendanhiggins at google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Reviewed-by: Logan Gunthorpe <logang at deltatee.com>
---
Changes Since Last Revision:
 - Found and fixed bug in resource deallocation logic. Bug was
   discovered as a result of making a change suggested by Stephen Boyd.
   This does not substantially change how any of the code works
   conceptually.
---
 include/kunit/test.h | 110 +++++++++++++++++++++++++++++++++++++++++++
 kunit/test.c         |  95 +++++++++++++++++++++++++++++++++++++
 2 files changed, 205 insertions(+)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 8476b3d371cb9..27bd95b6b5523 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -10,6 +10,70 @@
 #define _KUNIT_TEST_H
 
 #include <linux/types.h>
+#include <linux/slab.h>
+
+struct kunit_resource;
+
+typedef int (*kunit_resource_init_t)(struct kunit_resource *, void *);
+typedef void (*kunit_resource_free_t)(struct kunit_resource *);
+
+/**
+ * struct kunit_resource - represents a *test managed resource*
+ * @allocation: for the user to store arbitrary data.
+ * @free: a user supplied function to free the resource. Populated by
+ * kunit_alloc_resource().
+ *
+ * Represents a *test managed resource*, a resource which will automatically be
+ * cleaned up at the end of a test case.
+ *
+ * Example:
+ *
+ * .. code-block:: c
+ *
+ *	struct kunit_kmalloc_params {
+ *		size_t size;
+ *		gfp_t gfp;
+ *	};
+ *
+ *	static int kunit_kmalloc_init(struct kunit_resource *res, void *context)
+ *	{
+ *		struct kunit_kmalloc_params *params = context;
+ *		res->allocation = kmalloc(params->size, params->gfp);
+ *
+ *		if (!res->allocation)
+ *			return -ENOMEM;
+ *
+ *		return 0;
+ *	}
+ *
+ *	static void kunit_kmalloc_free(struct kunit_resource *res)
+ *	{
+ *		kfree(res->allocation);
+ *	}
+ *
+ *	void *kunit_kmalloc(struct kunit *test, size_t size, gfp_t gfp)
+ *	{
+ *		struct kunit_kmalloc_params params;
+ *		struct kunit_resource *res;
+ *
+ *		params.size = size;
+ *		params.gfp = gfp;
+ *
+ *		res = kunit_alloc_resource(test, kunit_kmalloc_init,
+ *			kunit_kmalloc_free, &params);
+ *		if (res)
+ *			return res->allocation;
+ *
+ *		return NULL;
+ *	}
+ */
+struct kunit_resource {
+	void *allocation;
+	kunit_resource_free_t free;
+
+	/* private: internal use only. */
+	struct list_head node;
+};
 
 struct kunit;
 
@@ -103,6 +167,7 @@ struct kunit {
 	const char *name; /* Read only after initialization! */
 	spinlock_t lock; /* Gaurds all mutable test state. */
 	bool success; /* Protected by lock. */
+	struct list_head resources; /* Protected by lock. */
 };
 
 void kunit_init_test(struct kunit *test, const char *name);
@@ -123,6 +188,51 @@ int kunit_run_tests(struct kunit_module *module);
 		} \
 		late_initcall(module_kunit_init##module)
 
+/**
+ * kunit_alloc_resource() - Allocates a *test managed resource*.
+ * @test: The test context object.
+ * @init: a user supplied function to initialize the resource.
+ * @free: a user supplied function to free the resource.
+ * @context: for the user to pass in arbitrary data to the init function.
+ *
+ * Allocates a *test managed resource*, a resource which will automatically be
+ * cleaned up at the end of a test case. See &struct kunit_resource for an
+ * example.
+ */
+struct kunit_resource *kunit_alloc_resource(struct kunit *test,
+					    kunit_resource_init_t init,
+					    kunit_resource_free_t free,
+					    void *context);
+
+void kunit_free_resource(struct kunit *test, struct kunit_resource *res);
+
+/**
+ * kunit_kmalloc() - Like kmalloc() except the allocation is *test managed*.
+ * @test: The test context object.
+ * @size: The size in bytes of the desired memory.
+ * @gfp: flags passed to underlying kmalloc().
+ *
+ * Just like `kmalloc(...)`, except the allocation is managed by the test case
+ * and is automatically cleaned up after the test case concludes. See &struct
+ * kunit_resource for more information.
+ */
+void *kunit_kmalloc(struct kunit *test, size_t size, gfp_t gfp);
+
+/**
+ * kunit_kzalloc() - Just like kunit_kmalloc(), but zeroes the allocation.
+ * @test: The test context object.
+ * @size: The size in bytes of the desired memory.
+ * @gfp: flags passed to underlying kmalloc().
+ *
+ * See kzalloc() and kunit_kmalloc() for more information.
+ */
+static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
+{
+	return kunit_kmalloc(test, size, gfp | __GFP_ZERO);
+}
+
+void kunit_cleanup(struct kunit *test);
+
 void __printf(3, 4) kunit_printk(const char *level,
 				 const struct kunit *test,
 				 const char *fmt, ...);
diff --git a/kunit/test.c b/kunit/test.c
index d05d254f1521f..53838f5394303 100644
--- a/kunit/test.c
+++ b/kunit/test.c
@@ -142,6 +142,7 @@ static void kunit_print_test_case_ok_not_ok(struct kunit_case *test_case,
 void kunit_init_test(struct kunit *test, const char *name)
 {
 	spin_lock_init(&test->lock);
+	INIT_LIST_HEAD(&test->resources);
 	test->name = name;
 	test->success = true;
 }
@@ -172,6 +173,8 @@ static void kunit_run_case(struct kunit_module *module,
 	if (module->exit)
 		module->exit(&test);
 
+	kunit_cleanup(&test);
+
 	test_case->success = kunit_get_success(&test);
 }
 
@@ -192,6 +195,98 @@ int kunit_run_tests(struct kunit_module *module)
 	return 0;
 }
 
+struct kunit_resource *kunit_alloc_resource(struct kunit *test,
+					    kunit_resource_init_t init,
+					    kunit_resource_free_t free,
+					    void *context)
+{
+	struct kunit_resource *res;
+	unsigned long flags;
+	int ret;
+
+	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	if (!res)
+		return NULL;
+
+	ret = init(res, context);
+	if (ret)
+		return NULL;
+
+	res->free = free;
+	spin_lock_irqsave(&test->lock, flags);
+	list_add_tail(&res->node, &test->resources);
+	spin_unlock_irqrestore(&test->lock, flags);
+
+	return res;
+}
+
+void kunit_free_resource(struct kunit *test, struct kunit_resource *res)
+{
+	res->free(res);
+	list_del(&res->node);
+	kfree(res);
+}
+
+struct kunit_kmalloc_params {
+	size_t size;
+	gfp_t gfp;
+};
+
+static int kunit_kmalloc_init(struct kunit_resource *res, void *context)
+{
+	struct kunit_kmalloc_params *params = context;
+
+	res->allocation = kmalloc(params->size, params->gfp);
+	if (!res->allocation)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void kunit_kmalloc_free(struct kunit_resource *res)
+{
+	kfree(res->allocation);
+}
+
+void *kunit_kmalloc(struct kunit *test, size_t size, gfp_t gfp)
+{
+	struct kunit_kmalloc_params params;
+	struct kunit_resource *res;
+
+	params.size = size;
+	params.gfp = gfp;
+
+	res = kunit_alloc_resource(test,
+				   kunit_kmalloc_init,
+				   kunit_kmalloc_free,
+				   &params);
+
+	if (res)
+		return res->allocation;
+
+	return NULL;
+}
+
+void kunit_cleanup(struct kunit *test)
+{
+	struct kunit_resource *resource, *resource_safe;
+	unsigned long flags;
+
+	spin_lock_irqsave(&test->lock, flags);
+	/*
+	 * test->resources is a stack - each allocation must be freed in the
+	 * reverse order from which it was added since one resource may depend
+	 * on another for its entire lifetime.
+	 */
+	list_for_each_entry_safe_reverse(resource,
+					 resource_safe,
+					 &test->resources,
+					 node) {
+		kunit_free_resource(test, resource);
+	}
+	spin_unlock_irqrestore(&test->lock, flags);
+}
+
 void kunit_printk(const char *level,
 		  const struct kunit *test,
 		  const char *fmt, ...)
-- 
2.22.0.410.gd8fdbe21b5-goog