char: misc: Adapt and add test cases for simple minor space division

Adapt and add test cases for next change which regards minor whose
value > macro MISC_DYNAMIC_MINOR as invalid parameter when register
miscdevice, hence get a simple minor space division below:

<  MISC_DYNAMIC_MINOR: fixed minor code
== MISC_DYNAMIC_MINOR: indicator to request dynamic minor code
>  MISC_DYNAMIC_MINOR: dynamic minor code requested

Signed-off-by: Zijun Hu <zijun.hu@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250714-rfc_miscdev-v6-2-2ed949665bde@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/misc_minor_kunit.c b/drivers/char/misc_minor_kunit.c
index 30eceac5f1b6402b0f918af6f56602ed1a6c14ec..3184f383bea8c77cbca69ff5e315ea5de2d5512e 100644 (file)
--- a/drivers/char/misc_minor_kunit.c
+++ b/drivers/char/misc_minor_kunit.c
@@ -7,12 +7,6 @@
 #include <linux/file.h>
 #include <linux/init_syscalls.h>
 
-/* dynamic minor (2) */
-static struct miscdevice dev_dynamic_minor = {
-       .minor  = 2,
-       .name   = "dev_dynamic_minor",
-};
-
 /* static minor (LCD_MINOR) */
 static struct miscdevice dev_static_minor = {
        .minor  = LCD_MINOR,
@@ -25,16 +19,6 @@ static struct miscdevice dev_misc_dynamic_minor = {
        .name   = "dev_misc_dynamic_minor",
 };
 
-static void kunit_dynamic_minor(struct kunit *test)
-{
-       int ret;
-
-       ret = misc_register(&dev_dynamic_minor);
-       KUNIT_EXPECT_EQ(test, 0, ret);
-       KUNIT_EXPECT_EQ(test, 2, dev_dynamic_minor.minor);
-       misc_deregister(&dev_dynamic_minor);
-}
-
 static void kunit_static_minor(struct kunit *test)
 {
        int ret;
@@ -157,13 +141,7 @@ static bool is_valid_dynamic_minor(int minor)
 {
        if (minor < 0)
                return false;
-       if (minor == MISC_DYNAMIC_MINOR)
-               return false;
-       if (minor >= 0 && minor <= 15)
-               return false;
-       if (minor >= 128 && minor < MISC_DYNAMIC_MINOR)
-               return false;
-       return true;
+       return minor > MISC_DYNAMIC_MINOR;
 }
 
 static int miscdev_test_open(struct inode *inode, struct file *file)
@@ -557,7 +535,7 @@ static void __init miscdev_test_conflict(struct kunit *test)
         */
        miscstat.minor = miscdyn.minor;
        ret = misc_register(&miscstat);
-       KUNIT_EXPECT_EQ(test, ret, -EBUSY);
+       KUNIT_EXPECT_EQ(test, ret, -EINVAL);
        if (ret == 0)
                misc_deregister(&miscstat);
 
@@ -590,8 +568,9 @@ static void __init miscdev_test_conflict_reverse(struct kunit *test)
        misc_deregister(&miscdyn);
 
        ret = misc_register(&miscstat);
-       KUNIT_EXPECT_EQ(test, ret, 0);
-       KUNIT_EXPECT_EQ(test, miscstat.minor, miscdyn.minor);
+       KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+       if (ret == 0)
+               misc_deregister(&miscstat);
 
        /*
         * Try to register a dynamic minor after registering a static minor
@@ -601,20 +580,32 @@ static void __init miscdev_test_conflict_reverse(struct kunit *test)
        miscdyn.minor = MISC_DYNAMIC_MINOR;
        ret = misc_register(&miscdyn);
        KUNIT_EXPECT_EQ(test, ret, 0);
-       KUNIT_EXPECT_NE(test, miscdyn.minor, miscstat.minor);
+       KUNIT_EXPECT_EQ(test, miscdyn.minor, miscstat.minor);
        KUNIT_EXPECT_TRUE(test, is_valid_dynamic_minor(miscdyn.minor));
        if (ret == 0)
                misc_deregister(&miscdyn);
+}
 
-       miscdev_test_can_open(test, &miscstat);
+/* 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;
 
-       misc_deregister(&miscstat);
+       ret = misc_register(&misc_test);
+       KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+       if (ret == 0)
+               misc_deregister(&misc_test);
 }
 
 static struct kunit_case test_cases[] = {
-       KUNIT_CASE(kunit_dynamic_minor),
        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),