of: overlay: unittest: add tests for overlay notifiers

Add tests for overlay apply and remove notifiers.  Trigger errors
for each of the notifier actions.

These tests will reveal a memory leak problem when a notifier returns
an error for action OF_OVERLAY_POST_APPLY.  The pr_err() message is:

   OF: ERROR: memory leak, expected refcount 1 instead of 3,
   of_node_get()/of_node_put() unbalanced - destroy cset entry: attach
   overlay node /testcase-data/overlay-node/test-bus/test-unittest17
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220502181742.1402826-3-frowand.list@gmail.com

drivers/of/unittest-data/Makefile

@@ -17,6 +17,11 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtb.o \
 			    overlay_12.dtb.o \
 			    overlay_13.dtb.o \
 			    overlay_15.dtb.o \
+			    overlay_16.dtb.o \
+			    overlay_17.dtb.o \
+			    overlay_18.dtb.o \
+			    overlay_19.dtb.o \
+			    overlay_20.dtb.o \
 			    overlay_bad_add_dup_node.dtb.o \
 			    overlay_bad_add_dup_prop.dtb.o \
 			    overlay_bad_phandle.dtb.o \
@@ -75,6 +80,11 @@ apply_static_overlay_1 := overlay_0.dtbo \
 			  overlay_12.dtbo \
 			  overlay_13.dtbo \
 			  overlay_15.dtbo \
+			  overlay_16.dtbo \
+			  overlay_17.dtbo \
+			  overlay_18.dtbo \
+			  overlay_19.dtbo \
+			  overlay_20.dtbo \
 			  overlay_gpio_01.dtbo \
 			  overlay_gpio_02a.dtbo \
 			  overlay_gpio_02b.dtbo \

drivers/of/unittest-data/overlay_16.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_16 - notify test */
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	test-unittest16 {
+		compatible = "unittest";
+		reg = <16>;
+	};
+};

drivers/of/unittest-data/overlay_17.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_17 - notify test */
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	test-unittest17 {
+		compatible = "unittest";
+		reg = <17>;
+	};
+};

drivers/of/unittest-data/overlay_18.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_18 - notify test */
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	test-unittest18 {
+		compatible = "unittest";
+		reg = <18>;
+	};
+};

drivers/of/unittest-data/overlay_19.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_19 - notify test */
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	test-unittest19 {
+		compatible = "unittest";
+		reg = <19>;
+	};
+};

drivers/of/unittest-data/overlay_20.dts

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_20 - notify test */
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	test-unittest20 {
+		compatible = "unittest";
+		reg = <20>;
+	};
+};

drivers/of/unittest.c

@@ -2741,6 +2741,189 @@ static inline void of_unittest_overlay_i2c_15(void) { }
 
 #endif
 
+static int of_notify(struct notifier_block *nb, unsigned long action,
+		     void *arg)
+{
+	struct of_overlay_notify_data *nd = arg;
+	struct device_node *found;
+	int ret;
+
+	/*
+	 * For overlay_16 .. overlay_19, check that returning an error
+	 * works for each of the actions by setting an arbitrary return
+	 * error number that matches the test number.  e.g. for unittest16,
+	 * ret = -EBUSY which is -16.
+	 *
+	 * OVERLAY_INFO() for the overlays is declared to expect the same
+	 * error number, so overlay_data_apply() will return no error.
+	 *
+	 * overlay_20 will return NOTIFY_DONE
+	 */
+
+	ret = 0;
+	of_node_get(nd->overlay);
+
+	switch (action) {
+
+	case OF_OVERLAY_PRE_APPLY:
+		found = of_find_node_by_name(nd->overlay, "test-unittest16");
+		if (found) {
+			of_node_put(found);
+			ret = -EBUSY;
+		}
+		break;
+
+	case OF_OVERLAY_POST_APPLY:
+		found = of_find_node_by_name(nd->overlay, "test-unittest17");
+		if (found) {
+			of_node_put(found);
+			ret = -EEXIST;
+		}
+		break;
+
+	case OF_OVERLAY_PRE_REMOVE:
+		found = of_find_node_by_name(nd->overlay, "test-unittest18");
+		if (found) {
+			of_node_put(found);
+			ret = -EXDEV;
+		}
+		break;
+
+	case OF_OVERLAY_POST_REMOVE:
+		found = of_find_node_by_name(nd->overlay, "test-unittest19");
+		if (found) {
+			of_node_put(found);
+			ret = -ENODEV;
+		}
+		break;
+
+	default:			/* should not happen */
+		of_node_put(nd->overlay);
+		ret = -EINVAL;
+		break;
+	}
+
+	if (ret)
+		return notifier_from_errno(ret);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block of_nb = {
+	.notifier_call = of_notify,
+};
+
+static void __init of_unittest_overlay_notify(void)
+{
+	int ovcs_id;
+	int ret;
+
+	ret = of_overlay_notifier_register(&of_nb);
+	unittest(!ret,
+		 "of_overlay_notifier_register() failed, ret = %d\n", ret);
+	if (ret)
+		return;
+
+	/*
+	 * The overlays are applied by overlay_data_apply()
+	 * instead of of_unittest_apply_overlay() so that they
+	 * will not be tracked.  Thus they will not be removed
+	 * by of_unittest_remove_tracked_overlays().
+	 *
+	 * Applying overlays 16 - 19 will each trigger an error for a
+	 * different action in of_notify().
+	 *
+	 * Applying overlay 20 will not trigger any error in of_notify().
+	 */
+
+	/* ---  overlay 16  --- */
+
+	EXPECT_BEGIN(KERN_INFO, "OF: overlay: overlay changeset pre-apply notifier error -16, target: /testcase-data/overlay-node/test-bus");
+
+	unittest(overlay_data_apply("overlay_16", &ovcs_id),
+		 "test OF_OVERLAY_PRE_APPLY notify injected error\n");
+
+	EXPECT_END(KERN_INFO, "OF: overlay: overlay changeset pre-apply notifier error -16, target: /testcase-data/overlay-node/test-bus");
+
+	unittest(!ovcs_id, "ovcs_id created for overlay_16\n");
+
+	/* ---  overlay 17  --- */
+
+	EXPECT_BEGIN(KERN_INFO, "OF: overlay: overlay changeset post-apply notifier error -17, target: /testcase-data/overlay-node/test-bus");
+
+	unittest(overlay_data_apply("overlay_17", &ovcs_id),
+		 "test OF_OVERLAY_POST_APPLY notify injected error\n");
+
+	EXPECT_END(KERN_INFO, "OF: overlay: overlay changeset post-apply notifier error -17, target: /testcase-data/overlay-node/test-bus");
+
+	unittest(!ovcs_id, "ovcs_id created for overlay_17\n");
+
+	/* ---  overlay 18  --- */
+
+	unittest(overlay_data_apply("overlay_18", &ovcs_id),
+		 "OF_OVERLAY_PRE_REMOVE notify injected error\n");
+
+	unittest(ovcs_id, "ovcs_id not created for overlay_18\n");
+
+	if (ovcs_id) {
+		EXPECT_BEGIN(KERN_INFO, "OF: overlay: overlay changeset pre-remove notifier error -18, target: /testcase-data/overlay-node/test-bus");
+
+		ret = of_overlay_remove(&ovcs_id);
+		EXPECT_END(KERN_INFO, "OF: overlay: overlay changeset pre-remove notifier error -18, target: /testcase-data/overlay-node/test-bus");
+		if (ret == -EXDEV) {
+			/*
+			 * change set ovcs_id should still exist
+			 */
+			unittest(1, "overlay_18 of_overlay_remove() injected error for OF_OVERLAY_PRE_REMOVE\n");
+		} else {
+			unittest(0, "overlay_18 of_overlay_remove() injected error for OF_OVERLAY_PRE_REMOVE not returned\n");
+		}
+	} else {
+		unittest(1, "ovcs_id not created for overlay_18\n");
+	}
+
+	unittest(ovcs_id, "ovcs_id removed for overlay_18\n");
+
+	/* ---  overlay 19  --- */
+
+	unittest(overlay_data_apply("overlay_19", &ovcs_id),
+		 "OF_OVERLAY_POST_REMOVE notify injected error\n");
+
+	unittest(ovcs_id, "ovcs_id not created for overlay_19\n");
+
+	if (ovcs_id) {
+		EXPECT_BEGIN(KERN_INFO, "OF: overlay: overlay changeset post-remove notifier error -19, target: /testcase-data/overlay-node/test-bus");
+		ret = of_overlay_remove(&ovcs_id);
+		EXPECT_END(KERN_INFO, "OF: overlay: overlay changeset post-remove notifier error -19, target: /testcase-data/overlay-node/test-bus");
+		if (ret == -ENODEV)
+			unittest(1, "overlay_19 of_overlay_remove() injected error for OF_OVERLAY_POST_REMOVE\n");
+		else
+			unittest(0, "overlay_19 of_overlay_remove() injected error for OF_OVERLAY_POST_REMOVE not returned\n");
+	} else {
+		unittest(1, "ovcs_id removed for overlay_19\n");
+	}
+
+	unittest(!ovcs_id, "changeset ovcs_id = %d not removed for overlay_19\n",
+		 ovcs_id);
+
+	/* ---  overlay 20  --- */
+
+	unittest(overlay_data_apply("overlay_20", &ovcs_id),
+		 "overlay notify no injected error\n");
+
+	if (ovcs_id) {
+		ret = of_overlay_remove(&ovcs_id);
+		if (ret)
+			unittest(1, "overlay_20 failed to be destroyed, ret = %d\n",
+				 ret);
+	} else {
+		unittest(1, "ovcs_id not created for overlay_20\n");
+	}
+
+	unittest(!of_overlay_notifier_unregister(&of_nb),
+		 "of_overlay_notifier_unregister() failed, ret = %d\n", ret);
+}
+
 static void __init of_unittest_overlay(void)
 {
 	struct device_node *bus_np = NULL;
@@ -2804,6 +2987,8 @@ static void __init of_unittest_overlay(void)
 
 	of_unittest_remove_tracked_overlays();
 
+	of_unittest_overlay_notify();
+
 out:
 	of_node_put(bus_np);
 }
@@ -2855,6 +3040,11 @@ OVERLAY_INFO_EXTERN(overlay_11);
 OVERLAY_INFO_EXTERN(overlay_12);
 OVERLAY_INFO_EXTERN(overlay_13);
 OVERLAY_INFO_EXTERN(overlay_15);
+OVERLAY_INFO_EXTERN(overlay_16);
+OVERLAY_INFO_EXTERN(overlay_17);
+OVERLAY_INFO_EXTERN(overlay_18);
+OVERLAY_INFO_EXTERN(overlay_19);
+OVERLAY_INFO_EXTERN(overlay_20);
 OVERLAY_INFO_EXTERN(overlay_gpio_01);
 OVERLAY_INFO_EXTERN(overlay_gpio_02a);
 OVERLAY_INFO_EXTERN(overlay_gpio_02b);
@@ -2885,6 +3075,11 @@ static struct overlay_info overlays[] = {
 	OVERLAY_INFO(overlay_12, 0),
 	OVERLAY_INFO(overlay_13, 0),
 	OVERLAY_INFO(overlay_15, 0),
+	OVERLAY_INFO(overlay_16, -EBUSY),
+	OVERLAY_INFO(overlay_17, -EEXIST),
+	OVERLAY_INFO(overlay_18, 0),
+	OVERLAY_INFO(overlay_19, 0),
+	OVERLAY_INFO(overlay_20, 0),
 	OVERLAY_INFO(overlay_gpio_01, 0),
 	OVERLAY_INFO(overlay_gpio_02a, 0),
 	OVERLAY_INFO(overlay_gpio_02b, 0),