diff options
Diffstat (limited to 'drivers/char/misc.c')
| -rw-r--r-- | drivers/char/misc.c | 62 |
1 files changed, 36 insertions, 26 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 541edc26ec89..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 @@ -214,12 +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; @@ -228,6 +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) { @@ -235,6 +240,12 @@ 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); @@ -243,8 +254,8 @@ int misc_register(struct miscdevice *misc) 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); @@ -272,13 +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); @@ -286,15 +296,15 @@ EXPORT_SYMBOL(misc_deregister); 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_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; return 0; @@ -302,7 +312,7 @@ fail_printk: pr_err("unable to get major %d for misc devices\n", MISC_MAJOR); class_unregister(&misc_class); fail_remove: - if (ret) + if (misc_proc_file) remove_proc_entry("misc", NULL); return err; } |