Merge tag 'char-misc-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-miscHEADtorvalds/mastertorvalds/HEADmaster

Pull Char/Misc/IIO/Binder updates from Greg KH:
 "Here is the big set of char/misc/iio and other driver subsystem
  changes for 6.18-rc1.

  Loads of different stuff in here, it was a busy development cycle in
  lots of different subsystems, with over 27k new lines added to the
  tree.

  Included in here are:

   - IIO updates including new drivers, reworking of existing apis, and
     other goodness in the sensor subsystems

   - MEI driver updates and additions

   - NVMEM driver updates

   - slimbus removal for an unused driver and some other minor updates

   - coresight driver updates and additions

   - MHI driver updates

   - comedi driver updates and fixes

   - extcon driver updates

   - interconnect driver additions

   - eeprom driver updates and fixes

   - minor UIO driver updates

   - tiny W1 driver updates

  But the majority of new code is in the rust bindings and additions,
  which includes:

   - misc driver rust binding updates for read/write support, we can now
     write "normal" misc drivers in rust fully, and the sample driver
     shows how this can be done.

   - Initial framework for USB driver rust bindings, which are disabled
     for now in the build, due to limited support, but coming in through
     this tree due to dependencies on other rust binding changes that
     were in here. I'll be enabling these back on in the build in the
     usb.git tree after -rc1 is out so that developers can continue to
     work on these in linux-next over the next development cycle.

   - Android Binder driver implemented in Rust.

     This is the big one, and was driving a huge majority of the rust
     binding work over the past years. Right now there are two binder
     drivers in the kernel, selected only at build time as to which one
     to use as binder wants to be included in the system at boot time.

     The binder C maintainers all agreed on this, as eventually, they
     want the C code to be removed from the tree, but it will take a few
     releases to get there while both are maintained to ensure that the
     rust implementation is fully stable and compliant with the existing
     userspace apis.

  All of these have been in linux-next for a while"

* tag 'char-misc-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (320 commits)
  rust: usb: keep usb::Device private for now
  rust: usb: don't retain device context for the interface parent
  USB: disable rust bindings from the build for now
  samples: rust: add a USB driver sample
  rust: usb: add basic USB abstractions
  coresight: Add label sysfs node support
  dt-bindings: arm: Add label in the coresight components
  coresight: tnoc: add new AMBA ID to support Trace Noc V2
  coresight: Fix incorrect handling for return value of devm_kzalloc
  coresight: tpda: fix the logic to setup the element size
  coresight: trbe: Return NULL pointer for allocation failures
  coresight: Refactor runtime PM
  coresight: Make clock sequence consistent
  coresight: Refactor driver data allocation
  coresight: Consolidate clock enabling
  coresight: Avoid enable programming clock duplicately
  coresight: Appropriately disable trace bus clocks
  coresight: Appropriately disable programming clocks
  coresight: etm4x: Support atclk
  coresight: catu: Support atclk
  ...

5 files changed, 706 insertions, 9 deletions

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index e9b360cdc99a..1291369b9126 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -6,6 +6,7 @@
 obj-y				+= mem.o random.o
 obj-$(CONFIG_TTY_PRINTK)	+= ttyprintk.o
 obj-y				+= misc.o
+obj-$(CONFIG_TEST_MISC_MINOR)	+= misc_minor_kunit.o
 obj-$(CONFIG_ATARI_DSP56K)	+= dsp56k.o
 obj-$(CONFIG_VIRTIO_CONSOLE)	+= virtio_console.o
 obj-$(CONFIG_UV_MMTIMER)	+= uv_mmtimer.o
diff --git a/drivers/char/adi.c b/drivers/char/adi.c
index f9bec10a6064..4312b0cc391c 100644
--- a/drivers/char/adi.c
+++ b/drivers/char/adi.c
@@ -131,7 +131,7 @@ static ssize_t adi_write(struct file *file, const char __user *buf,
 	ssize_t ret;
 	int i;
 
-	if (count <= 0)
+	if (count == 0)
 		return -EINVAL;
 
 	ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 0713ea2b2a51..4f5ccd3a1f56 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -867,7 +867,7 @@ int hpet_alloc(struct hpet_data *hdp)
 
 	printk(KERN_INFO "hpet%u: at MMIO 0x%lx, IRQ%s",
 		hpetp->hp_which, hdp->hd_phys_address,
-		hpetp->hp_ntimer > 1 ? "s" : "");
+		str_plural(hpetp->hp_ntimer));
 	for (i = 0; i < hpetp->hp_ntimer; i++)
 		printk(KERN_CONT "%s %u", i > 0 ? "," : "", hdp->hd_irq[i]);
 	printk(KERN_CONT "\n");
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 558302a64dd9..726516fb0a3b 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -132,7 +132,8 @@ static int misc_open(struct inode *inode, struct file *file)
 		break;
 	}
 
-	if (!new_fops) {
+	/* Only request module for fixed minor code */
+	if (!new_fops && minor < MISC_DYNAMIC_MINOR) {
 		mutex_unlock(&misc_mtx);
 		request_module("char-major-%d-%d", MISC_MAJOR, minor);
 		mutex_lock(&misc_mtx);
@@ -144,10 +145,11 @@ static int misc_open(struct inode *inode, struct file *file)
 			new_fops = fops_get(iter->fops);
 			break;
 		}
-		if (!new_fops)
-			goto fail;
 	}
 
+	if (!new_fops)
+		goto fail;
+
 	/*
 	 * Place the miscdevice in the file's
 	 * private_data so it can be used by the
@@ -210,6 +212,12 @@ int misc_register(struct miscdevice *misc)
 	int err = 0;
 	bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);
 
+	if (misc->minor > MISC_DYNAMIC_MINOR) {
+		pr_err("Invalid fixed minor %d for miscdevice '%s'\n",
+		       misc->minor, misc->name);
+		return -EINVAL;
+	}
+
 	INIT_LIST_HEAD(&misc->list);
 
 	mutex_lock(&misc_mtx);
@@ -275,13 +283,12 @@ EXPORT_SYMBOL(misc_register);
 
 void misc_deregister(struct miscdevice *misc)
 {
-	if (WARN_ON(list_empty(&misc->list)))
-		return;
-
 	mutex_lock(&misc_mtx);
-	list_del(&misc->list);
+	list_del_init(&misc->list);
 	device_destroy(&misc_class, MKDEV(MISC_MAJOR, misc->minor));
 	misc_minor_free(misc->minor);
+	if (misc->minor > MISC_DYNAMIC_MINOR)
+		misc->minor = MISC_DYNAMIC_MINOR;
 	mutex_unlock(&misc_mtx);
 }
 EXPORT_SYMBOL(misc_deregister);
diff --git a/drivers/char/misc_minor_kunit.c b/drivers/char/misc_minor_kunit.c
new file mode 100644
index 000000000000..6fc8b05169c5
--- /dev/null
+++ b/drivers/char/misc_minor_kunit.c
@@ -0,0 +1,689 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <kunit/test.h>
+#include <kunit/test-bug.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/init_syscalls.h>
+
+/* static minor (LCD_MINOR) */
+static struct miscdevice dev_static_minor = {
+	.minor  = LCD_MINOR,
+	.name   = "dev_static_minor",
+};
+
+/* misc dynamic minor */
+static struct miscdevice dev_misc_dynamic_minor = {
+	.minor  = MISC_DYNAMIC_MINOR,
+	.name   = "dev_misc_dynamic_minor",
+};
+
+static void kunit_static_minor(struct kunit *test)
+{
+	int ret;
+
+	ret = misc_register(&dev_static_minor);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, LCD_MINOR, dev_static_minor.minor);
+	misc_deregister(&dev_static_minor);
+}
+
+static void kunit_misc_dynamic_minor(struct kunit *test)
+{
+	int ret;
+
+	ret = misc_register(&dev_misc_dynamic_minor);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	misc_deregister(&dev_misc_dynamic_minor);
+}
+
+struct miscdev_test_case {
+	const char *str;
+	int minor;
+};
+
+static struct miscdev_test_case miscdev_test_ranges[] = {
+	{
+		.str = "lower static range, top",
+		.minor = 15,
+	},
+	{
+		.str = "upper static range, bottom",
+		.minor = 130,
+	},
+	{
+		.str = "lower static range, bottom",
+		.minor = 0,
+	},
+	{
+		.str = "upper static range, top",
+		.minor = MISC_DYNAMIC_MINOR - 1,
+	},
+};
+
+KUNIT_ARRAY_PARAM_DESC(miscdev, miscdev_test_ranges, str);
+
+static int miscdev_find_minors(struct kunit_suite *suite)
+{
+	int ret;
+	struct miscdevice miscstat = {
+		.name = "miscstat",
+	};
+	int i;
+
+	for (i = 15; i >= 0; i--) {
+		miscstat.minor = i;
+		ret = misc_register(&miscstat);
+		if (ret == 0)
+			break;
+	}
+
+	if (ret == 0) {
+		kunit_info(suite, "found misc device minor %d available\n",
+				miscstat.minor);
+		miscdev_test_ranges[0].minor = miscstat.minor;
+		misc_deregister(&miscstat);
+	} else {
+		return ret;
+	}
+
+	for (i = 128; i < MISC_DYNAMIC_MINOR; i++) {
+		miscstat.minor = i;
+		ret = misc_register(&miscstat);
+		if (ret == 0)
+			break;
+	}
+
+	if (ret == 0) {
+		kunit_info(suite, "found misc device minor %d available\n",
+				miscstat.minor);
+		miscdev_test_ranges[1].minor = miscstat.minor;
+		misc_deregister(&miscstat);
+	} else {
+		return ret;
+	}
+
+	for (i = 0; i < miscdev_test_ranges[0].minor; i++) {
+		miscstat.minor = i;
+		ret = misc_register(&miscstat);
+		if (ret == 0)
+			break;
+	}
+
+	if (ret == 0) {
+		kunit_info(suite, "found misc device minor %d available\n",
+			miscstat.minor);
+		miscdev_test_ranges[2].minor = miscstat.minor;
+		misc_deregister(&miscstat);
+	} else {
+		return ret;
+	}
+
+	for (i = MISC_DYNAMIC_MINOR - 1; i > miscdev_test_ranges[1].minor; i--) {
+		miscstat.minor = i;
+		ret = misc_register(&miscstat);
+		if (ret == 0)
+			break;
+	}
+
+	if (ret == 0) {
+		kunit_info(suite, "found misc device minor %d available\n",
+			miscstat.minor);
+		miscdev_test_ranges[3].minor = miscstat.minor;
+		misc_deregister(&miscstat);
+	}
+
+	return ret;
+}
+
+static bool is_valid_dynamic_minor(int minor)
+{
+	if (minor < 0)
+		return false;
+	return minor > MISC_DYNAMIC_MINOR;
+}
+
+static int miscdev_test_open(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static const struct file_operations miscdev_test_fops = {
+	.open	= miscdev_test_open,
+};
+
+static void __init miscdev_test_can_open(struct kunit *test, struct miscdevice *misc)
+{
+	int ret;
+	struct file *filp;
+	char *devname;
+
+	devname = kasprintf(GFP_KERNEL, "/dev/%s", misc->name);
+	ret = init_mknod(devname, S_IFCHR | 0600,
+			 new_encode_dev(MKDEV(MISC_MAJOR, misc->minor)));
+	if (ret != 0)
+		KUNIT_FAIL(test, "failed to create node\n");
+
+	filp = filp_open(devname, O_RDONLY, 0);
+	if (IS_ERR_OR_NULL(filp))
+		KUNIT_FAIL(test, "failed to open misc device: %ld\n", PTR_ERR(filp));
+	else
+		fput(filp);
+
+	init_unlink(devname);
+	kfree(devname);
+}
+
+static void __init miscdev_test_static_basic(struct kunit *test)
+{
+	struct miscdevice misc_test = {
+		.name = "misc_test",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+	const struct miscdev_test_case *params = test->param_value;
+
+	misc_test.minor = params->minor;
+
+	ret = misc_register(&misc_test);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, misc_test.minor, params->minor);
+
+	if (ret == 0) {
+		miscdev_test_can_open(test, &misc_test);
+		misc_deregister(&misc_test);
+	}
+}
+
+static void __init miscdev_test_dynamic_basic(struct kunit *test)
+{
+	struct miscdevice misc_test = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc_test",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+
+	ret = misc_register(&misc_test);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(misc_test.minor));
+
+	if (ret == 0) {
+		miscdev_test_can_open(test, &misc_test);
+		misc_deregister(&misc_test);
+	}
+}
+
+static void miscdev_test_twice(struct kunit *test)
+{
+	struct miscdevice misc_test = {
+		.name = "misc_test",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+	const struct miscdev_test_case *params = test->param_value;
+
+	misc_test.minor = params->minor;
+
+	ret = misc_register(&misc_test);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, misc_test.minor, params->minor);
+	if (ret == 0)
+		misc_deregister(&misc_test);
+
+	ret = misc_register(&misc_test);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, misc_test.minor, params->minor);
+	if (ret == 0)
+		misc_deregister(&misc_test);
+}
+
+static void miscdev_test_duplicate_minor(struct kunit *test)
+{
+	struct miscdevice misc1 = {
+		.name = "misc1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice misc2 = {
+		.name = "misc2",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+	const struct miscdev_test_case *params = test->param_value;
+
+	misc1.minor = params->minor;
+	misc2.minor = params->minor;
+
+	ret = misc_register(&misc1);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, misc1.minor, params->minor);
+
+	ret = misc_register(&misc2);
+	KUNIT_EXPECT_EQ(test, ret, -EBUSY);
+	if (ret == 0)
+		misc_deregister(&misc2);
+
+	misc_deregister(&misc1);
+}
+
+static void miscdev_test_duplicate_name(struct kunit *test)
+{
+	struct miscdevice misc1 = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice misc2 = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc1",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+
+	ret = misc_register(&misc1);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(misc1.minor));
+
+	ret = misc_register(&misc2);
+	KUNIT_EXPECT_EQ(test, ret, -EEXIST);
+	if (ret == 0)
+		misc_deregister(&misc2);
+
+	misc_deregister(&misc1);
+}
+
+/*
+ * Test that after a duplicate name failure, the reserved minor number is
+ * freed to be allocated next.
+ */
+static void miscdev_test_duplicate_name_leak(struct kunit *test)
+{
+	struct miscdevice misc1 = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice misc2 = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice misc3 = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "misc3",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+	int dyn_minor;
+
+	ret = misc_register(&misc1);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(misc1.minor));
+
+	/*
+	 * Find out what is the next minor number available.
+	 */
+	ret = misc_register(&misc3);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(misc3.minor));
+	dyn_minor = misc3.minor;
+	misc_deregister(&misc3);
+	misc3.minor = MISC_DYNAMIC_MINOR;
+
+	ret = misc_register(&misc2);
+	KUNIT_EXPECT_EQ(test, ret, -EEXIST);
+	if (ret == 0)
+		misc_deregister(&misc2);
+
+	/*
+	 * Now check that we can still get the same minor we found before.
+	 */
+	ret = misc_register(&misc3);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(misc3.minor));
+	KUNIT_EXPECT_EQ(test, misc3.minor, dyn_minor);
+	misc_deregister(&misc3);
+
+	misc_deregister(&misc1);
+}
+
+/*
+ * Try to register a static minor with a duplicate name. That might not
+ * deallocate the minor, preventing it from being used again.
+ */
+static void miscdev_test_duplicate_error(struct kunit *test)
+{
+	struct miscdevice miscdyn = {
+		.minor = MISC_DYNAMIC_MINOR,
+		.name = "name1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice miscstat = {
+		.name = "name1",
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice miscnew = {
+		.name = "name2",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+	const struct miscdev_test_case *params = test->param_value;
+
+	miscstat.minor = params->minor;
+	miscnew.minor = params->minor;
+
+	ret = misc_register(&miscdyn);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn.minor));
+
+	ret = misc_register(&miscstat);
+	KUNIT_EXPECT_EQ(test, ret, -EEXIST);
+	if (ret == 0)
+		misc_deregister(&miscstat);
+
+	ret = misc_register(&miscnew);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, miscnew.minor, params->minor);
+	if (ret == 0)
+		misc_deregister(&miscnew);
+
+	misc_deregister(&miscdyn);
+}
+
+static void __init miscdev_test_dynamic_only_range(struct kunit *test)
+{
+	int ret;
+	struct miscdevice *miscdev;
+	const int dynamic_minors = 256;
+	int i;
+
+	miscdev = kunit_kmalloc_array(test, dynamic_minors,
+					sizeof(struct miscdevice),
+					GFP_KERNEL | __GFP_ZERO);
+
+	for (i = 0; i < dynamic_minors; i++) {
+		miscdev[i].minor = MISC_DYNAMIC_MINOR;
+		miscdev[i].name = kasprintf(GFP_KERNEL, "misc_test%d", i);
+		miscdev[i].fops = &miscdev_test_fops;
+		ret = misc_register(&miscdev[i]);
+		if (ret != 0)
+			break;
+		/*
+		 * This is the bug we are looking for!
+		 * We asked for a dynamic minor and got a minor in the static range space.
+		 */
+		if (miscdev[i].minor >= 0 && miscdev[i].minor <= 15) {
+			KUNIT_FAIL(test, "misc_register allocated minor %d\n", miscdev[i].minor);
+			i++;
+			break;
+		}
+		KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdev[i].minor));
+	}
+
+	for (i--; i >= 0; i--) {
+		miscdev_test_can_open(test, &miscdev[i]);
+		misc_deregister(&miscdev[i]);
+		kfree_const(miscdev[i].name);
+	}
+
+	KUNIT_EXPECT_EQ(test, ret, 0);
+}
+
+static void __init miscdev_test_collision(struct kunit *test)
+{
+	int ret;
+	struct miscdevice *miscdev;
+	struct miscdevice miscstat = {
+		.name = "miscstat",
+		.fops = &miscdev_test_fops,
+	};
+	const int dynamic_minors = 256;
+	int i;
+
+	miscdev = kunit_kmalloc_array(test, dynamic_minors,
+					sizeof(struct miscdevice),
+					GFP_KERNEL | __GFP_ZERO);
+
+	miscstat.minor = miscdev_test_ranges[0].minor;
+	ret = misc_register(&miscstat);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, miscstat.minor, miscdev_test_ranges[0].minor);
+
+	for (i = 0; i < dynamic_minors; i++) {
+		miscdev[i].minor = MISC_DYNAMIC_MINOR;
+		miscdev[i].name = kasprintf(GFP_KERNEL, "misc_test%d", i);
+		miscdev[i].fops = &miscdev_test_fops;
+		ret = misc_register(&miscdev[i]);
+		if (ret != 0)
+			break;
+		KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdev[i].minor));
+	}
+
+	for (i--; i >= 0; i--) {
+		miscdev_test_can_open(test, &miscdev[i]);
+		misc_deregister(&miscdev[i]);
+		kfree_const(miscdev[i].name);
+	}
+
+	misc_deregister(&miscstat);
+
+	KUNIT_EXPECT_EQ(test, ret, 0);
+}
+
+static void __init miscdev_test_collision_reverse(struct kunit *test)
+{
+	int ret;
+	struct miscdevice *miscdev;
+	struct miscdevice miscstat = {
+		.name = "miscstat",
+		.fops = &miscdev_test_fops,
+	};
+	const int dynamic_minors = 256;
+	int i;
+
+	miscdev = kunit_kmalloc_array(test, dynamic_minors,
+					sizeof(struct miscdevice),
+					GFP_KERNEL | __GFP_ZERO);
+
+	for (i = 0; i < dynamic_minors; i++) {
+		miscdev[i].minor = MISC_DYNAMIC_MINOR;
+		miscdev[i].name = kasprintf(GFP_KERNEL, "misc_test%d", i);
+		miscdev[i].fops = &miscdev_test_fops;
+		ret = misc_register(&miscdev[i]);
+		if (ret != 0)
+			break;
+		KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdev[i].minor));
+	}
+
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	miscstat.minor = miscdev_test_ranges[0].minor;
+	ret = misc_register(&miscstat);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, miscstat.minor, miscdev_test_ranges[0].minor);
+	if (ret == 0)
+		misc_deregister(&miscstat);
+
+	for (i--; i >= 0; i--) {
+		miscdev_test_can_open(test, &miscdev[i]);
+		misc_deregister(&miscdev[i]);
+		kfree_const(miscdev[i].name);
+	}
+}
+
+static void __init miscdev_test_conflict(struct kunit *test)
+{
+	int ret;
+	struct miscdevice miscdyn = {
+		.name = "miscdyn",
+		.minor = MISC_DYNAMIC_MINOR,
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice miscstat = {
+		.name = "miscstat",
+		.fops = &miscdev_test_fops,
+	};
+
+	ret = misc_register(&miscdyn);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn.minor));
+
+	/*
+	 * Try to register a static minor with the same minor as the
+	 * dynamic one.
+	 */
+	miscstat.minor = miscdyn.minor;
+	ret = misc_register(&miscstat);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+	if (ret == 0)
+		misc_deregister(&miscstat);
+
+	miscdev_test_can_open(test, &miscdyn);
+
+	misc_deregister(&miscdyn);
+}
+
+static void __init miscdev_test_conflict_reverse(struct kunit *test)
+{
+	int ret;
+	struct miscdevice miscdyn = {
+		.name = "miscdyn",
+		.minor = MISC_DYNAMIC_MINOR,
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice miscstat = {
+		.name = "miscstat",
+		.fops = &miscdev_test_fops,
+	};
+
+	/*
+	 * Find the first available dynamic minor to use it as a static
+	 * minor later on.
+	 */
+	ret = misc_register(&miscdyn);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn.minor));
+	miscstat.minor = miscdyn.minor;
+	misc_deregister(&miscdyn);
+
+	ret = misc_register(&miscstat);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+	if (ret == 0)
+		misc_deregister(&miscstat);
+
+	/*
+	 * Try to register a dynamic minor after registering a static minor
+	 * within the dynamic range. It should work but get a different
+	 * minor.
+	 */
+	miscdyn.minor = MISC_DYNAMIC_MINOR;
+	ret = misc_register(&miscdyn);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, miscdyn.minor, miscstat.minor);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn.minor));
+	if (ret == 0)
+		misc_deregister(&miscdyn);
+}
+
+/* Take minor(> MISC_DYNAMIC_MINOR) as invalid when register miscdevice */
+static void miscdev_test_invalid_input(struct kunit *test)
+{
+	struct miscdevice misc_test = {
+		.minor = MISC_DYNAMIC_MINOR + 1,
+		.name = "misc_test",
+		.fops = &miscdev_test_fops,
+	};
+	int ret;
+
+	ret = misc_register(&misc_test);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+	if (ret == 0)
+		misc_deregister(&misc_test);
+}
+
+/*
+ * Verify if @miscdyn_a can still be registered successfully without
+ * reinitialization even if its minor ever owned was requested by
+ * another miscdevice such as @miscdyn_b.
+ */
+static void miscdev_test_dynamic_reentry(struct kunit *test)
+{
+	struct miscdevice miscdyn_a = {
+		.name = "miscdyn_a",
+		.minor = MISC_DYNAMIC_MINOR,
+		.fops = &miscdev_test_fops,
+	};
+	struct miscdevice miscdyn_b = {
+		.name = "miscdyn_b",
+		.minor = MISC_DYNAMIC_MINOR,
+		.fops = &miscdev_test_fops,
+	};
+	int ret, minor_a;
+
+	ret = misc_register(&miscdyn_a);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn_a.minor));
+	minor_a = miscdyn_a.minor;
+	if (ret != 0)
+		return;
+	misc_deregister(&miscdyn_a);
+
+	ret = misc_register(&miscdyn_b);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, miscdyn_b.minor, minor_a);
+	if (ret != 0)
+		return;
+
+	ret = misc_register(&miscdyn_a);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn_a.minor));
+	KUNIT_EXPECT_NE(test, miscdyn_a.minor, miscdyn_b.minor);
+	if (ret == 0)
+		misc_deregister(&miscdyn_a);
+
+	misc_deregister(&miscdyn_b);
+}
+
+static struct kunit_case test_cases[] = {
+	KUNIT_CASE(kunit_static_minor),
+	KUNIT_CASE(kunit_misc_dynamic_minor),
+	KUNIT_CASE(miscdev_test_invalid_input),
+	KUNIT_CASE_PARAM(miscdev_test_twice, miscdev_gen_params),
+	KUNIT_CASE_PARAM(miscdev_test_duplicate_minor, miscdev_gen_params),
+	KUNIT_CASE(miscdev_test_duplicate_name),
+	KUNIT_CASE(miscdev_test_duplicate_name_leak),
+	KUNIT_CASE_PARAM(miscdev_test_duplicate_error, miscdev_gen_params),
+	KUNIT_CASE(miscdev_test_dynamic_reentry),
+	{}
+};
+
+static struct kunit_suite test_suite = {
+	.name = "miscdev",
+	.suite_init = miscdev_find_minors,
+	.test_cases = test_cases,
+};
+kunit_test_suite(test_suite);
+
+static struct kunit_case __refdata test_init_cases[] = {
+	KUNIT_CASE_PARAM(miscdev_test_static_basic, miscdev_gen_params),
+	KUNIT_CASE(miscdev_test_dynamic_basic),
+	KUNIT_CASE(miscdev_test_dynamic_only_range),
+	KUNIT_CASE(miscdev_test_collision),
+	KUNIT_CASE(miscdev_test_collision_reverse),
+	KUNIT_CASE(miscdev_test_conflict),
+	KUNIT_CASE(miscdev_test_conflict_reverse),
+	{}
+};
+
+static struct kunit_suite test_init_suite = {
+	.name = "miscdev_init",
+	.suite_init = miscdev_find_minors,
+	.test_cases = test_init_cases,
+};
+kunit_test_init_section_suite(test_init_suite);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Vimal Agrawal");
+MODULE_AUTHOR("Thadeu Lima de Souza Cascardo <cascardo@igalia.com>");
+MODULE_DESCRIPTION("Test module for misc character devices");