1 files changed, 56 insertions, 45 deletions

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 7a1388b0572b..726516fb0a3b 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -58,31 +58,27 @@ static LIST_HEAD(misc_list);
 static DEFINE_MUTEX(misc_mtx);
 
 /*
- * Assigned numbers, used for dynamic minors
+ * Assigned numbers.
  */
-#define DYNAMIC_MINORS 128 /* like dynamic majors */
 static DEFINE_IDA(misc_minors_ida);
 
-static int misc_minor_alloc(void)
+static int misc_minor_alloc(int minor)
 {
-	int ret;
+	int ret = 0;
 
-	ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);
-	if (ret >= 0) {
-		ret = DYNAMIC_MINORS - ret - 1;
-	} else {
+	if (minor == MISC_DYNAMIC_MINOR) {
+		/* allocate free id */
 		ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1,
 				      MINORMASK, GFP_KERNEL);
+	} else {
+		ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL);
 	}
 	return ret;
 }
 
 static void misc_minor_free(int minor)
 {
-	if (minor < DYNAMIC_MINORS)
-		ida_free(&misc_minors_ida, DYNAMIC_MINORS - minor - 1);
-	else if (minor > MISC_DYNAMIC_MINOR)
-		ida_free(&misc_minors_ida, minor);
+	ida_free(&misc_minors_ida, minor);
 }
 
 #ifdef CONFIG_PROC_FS
@@ -136,7 +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);
@@ -148,10 +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
@@ -168,7 +166,21 @@ fail:
 	return err;
 }
 
-static struct class *misc_class;
+static char *misc_devnode(const struct device *dev, umode_t *mode)
+{
+	const struct miscdevice *c = dev_get_drvdata(dev);
+
+	if (mode && c->mode)
+		*mode = c->mode;
+	if (c->nodename)
+		return kstrdup(c->nodename, GFP_KERNEL);
+	return NULL;
+}
+
+static const struct class misc_class = {
+	.name		= "misc",
+	.devnode	= misc_devnode,
+};
 
 static const struct file_operations misc_fops = {
 	.owner		= THIS_MODULE,
@@ -200,12 +212,18 @@ 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);
 
 	if (is_dynamic) {
-		int i = misc_minor_alloc();
+		int i = misc_minor_alloc(misc->minor);
 
 		if (i < 0) {
 			err = -EBUSY;
@@ -214,6 +232,7 @@ int misc_register(struct miscdevice *misc)
 		misc->minor = i;
 	} else {
 		struct miscdevice *c;
+		int i;
 
 		list_for_each_entry(c, &misc_list, list) {
 			if (c->minor == misc->minor) {
@@ -221,16 +240,22 @@ int misc_register(struct miscdevice *misc)
 				goto out;
 			}
 		}
+
+		i = misc_minor_alloc(misc->minor);
+		if (i < 0) {
+			err = -EBUSY;
+			goto out;
+		}
 	}
 
 	dev = MKDEV(MISC_MAJOR, misc->minor);
 
 	misc->this_device =
-		device_create_with_groups(misc_class, misc->parent, dev,
+		device_create_with_groups(&misc_class, misc->parent, dev,
 					  misc, misc->groups, "%s", misc->name);
 	if (IS_ERR(misc->this_device)) {
+		misc_minor_free(misc->minor);
 		if (is_dynamic) {
-			misc_minor_free(misc->minor);
 			misc->minor = MISC_DYNAMIC_MINOR;
 		}
 		err = PTR_ERR(misc->this_device);
@@ -258,50 +283,36 @@ 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);
-	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
+	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);
 
-static char *misc_devnode(const struct device *dev, umode_t *mode)
-{
-	const struct miscdevice *c = dev_get_drvdata(dev);
-
-	if (mode && c->mode)
-		*mode = c->mode;
-	if (c->nodename)
-		return kstrdup(c->nodename, GFP_KERNEL);
-	return NULL;
-}
-
 static int __init misc_init(void)
 {
 	int err;
-	struct proc_dir_entry *ret;
+	struct proc_dir_entry *misc_proc_file;
 
-	ret = proc_create_seq("misc", 0, NULL, &misc_seq_ops);
-	misc_class = class_create(THIS_MODULE, "misc");
-	err = PTR_ERR(misc_class);
-	if (IS_ERR(misc_class))
+	misc_proc_file = proc_create_seq("misc", 0, NULL, &misc_seq_ops);
+	err = class_register(&misc_class);
+	if (err)
 		goto fail_remove;
 
-	err = -EIO;
-	if (register_chrdev(MISC_MAJOR, "misc", &misc_fops))
+	err = __register_chrdev(MISC_MAJOR, 0, MINORMASK + 1, "misc", &misc_fops);
+	if (err < 0)
 		goto fail_printk;
-	misc_class->devnode = misc_devnode;
 	return 0;
 
 fail_printk:
 	pr_err("unable to get major %d for misc devices\n", MISC_MAJOR);
-	class_destroy(misc_class);
+	class_unregister(&misc_class);
 fail_remove:
-	if (ret)
+	if (misc_proc_file)
 		remove_proc_entry("misc", NULL);
 	return err;
 }