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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320// SPDX-License-Identifier: GPL-2.0/* * linux/drivers/char/misc.c * * Generic misc open routine by Johan Myreen * * Based on code from Linus * * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's * changes incorporated into 0.97pl4 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) * See busmouse.c for particulars. * * Made things a lot mode modular - easy to compile in just one or two * of the misc drivers, as they are now completely independent. Linus. * * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk> * * Fixed a failing symbol register to free the device registration * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96 * * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 * * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 * * Handling of mouse minor numbers for kerneld: * Idea by Jacques Gelinas <jack@solucorp.qc.ca>, * adapted by Bjorn Ekwall <bj0rn@blox.se> * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk> * * Changes for kmod (from kerneld): * Cyrus Durgin <cider@speakeasy.org> * * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998 */
#include <linux/module.h>
#include <linux/fs.h>#include <linux/errno.h>#include <linux/miscdevice.h>#include <linux/kernel.h>#include <linux/major.h>#include <linux/mutex.h>#include <linux/proc_fs.h>#include <linux/seq_file.h>#include <linux/stat.h>#include <linux/init.h>#include <linux/device.h>#include <linux/tty.h>#include <linux/kmod.h>#include <linux/gfp.h>
/* * Head entry for the doubly linked miscdevice list */static LIST_HEAD(misc_list);static DEFINE_MUTEX(misc_mtx);
/* * Assigned numbers. */static DEFINE_IDA(misc_minors_ida);
static int misc_minor_alloc(int minor){ int ret = 0;
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){ ida_free(&misc_minors_ida, minor);}
#ifdef CONFIG_PROC_FSstatic void *misc_seq_start(struct seq_file *seq, loff_t *pos){ mutex_lock(&misc_mtx); return seq_list_start(&misc_list, *pos);}
static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos){ return seq_list_next(v, &misc_list, pos);}
static void misc_seq_stop(struct seq_file *seq, void *v){ mutex_unlock(&misc_mtx);}
static int misc_seq_show(struct seq_file *seq, void *v){ const struct miscdevice *p = list_entry(v, struct miscdevice, list);
seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); return 0;}
static const struct seq_operations misc_seq_ops = { .start = misc_seq_start, .next = misc_seq_next, .stop = misc_seq_stop, .show = misc_seq_show,};#endif
static int misc_open(struct inode *inode, struct file *file){ int minor = iminor(inode); struct miscdevice *c = NULL, *iter; int err = -ENODEV; const struct file_operations *new_fops = NULL;
mutex_lock(&misc_mtx);
list_for_each_entry(iter, &misc_list, list) { if (iter->minor != minor) continue; c = iter; new_fops = fops_get(iter->fops); break; }
/* 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);
list_for_each_entry(iter, &misc_list, list) { if (iter->minor != minor) continue; c = iter; new_fops = fops_get(iter->fops); break; } }
if (!new_fops) goto fail;
/* * Place the miscdevice in the file's * private_data so it can be used by the * file operations, including f_op->open below */ file->private_data = c;
err = 0; replace_fops(file, new_fops); if (file->f_op->open) err = file->f_op->open(inode, file);fail: mutex_unlock(&misc_mtx); return err;}
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, .open = misc_open, .llseek = noop_llseek,};
/** * misc_register - register a miscellaneous device * @misc: device structure * * Register a miscellaneous device with the kernel. If the minor * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned * and placed in the minor field of the structure. For other cases * the minor number requested is used. * * The structure passed is linked into the kernel and may not be * destroyed until it has been unregistered. By default, an open() * syscall to the device sets file->private_data to point to the * structure. Drivers don't need open in fops for this. * * A zero is returned on success and a negative errno code for * failure. */
int misc_register(struct miscdevice *misc){ dev_t dev; 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(misc->minor);
if (i < 0) { err = -EBUSY; goto out; } misc->minor = i; } else { struct miscdevice *c; int i;
list_for_each_entry(c, &misc_list, list) { if (c->minor == misc->minor) { err = -EBUSY; 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, misc, misc->groups, "%s", misc->name); if (IS_ERR(misc->this_device)) { misc_minor_free(misc->minor); if (is_dynamic) { misc->minor = MISC_DYNAMIC_MINOR; } err = PTR_ERR(misc->this_device); goto out; }
/* * Add it to the front, so that later devices can "override" * earlier defaults */ list_add(&misc->list, &misc_list); out: mutex_unlock(&misc_mtx); return err;}EXPORT_SYMBOL(misc_register);
/** * misc_deregister - unregister a miscellaneous device * @misc: device to unregister * * Unregister a miscellaneous device that was previously * successfully registered with misc_register(). */
void misc_deregister(struct miscdevice *misc){ mutex_lock(&misc_mtx); 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 int __init misc_init(void){ int err; struct proc_dir_entry *misc_proc_file;
misc_proc_file = proc_create_seq("misc", 0, NULL, &misc_seq_ops); err = class_register(&misc_class); if (err) goto fail_remove;
err = __register_chrdev(MISC_MAJOR, 0, MINORMASK + 1, "misc", &misc_fops); if (err < 0) goto fail_printk; return 0;
fail_printk: pr_err("unable to get major %d for misc devices\n", MISC_MAJOR); class_unregister(&misc_class);fail_remove: if (misc_proc_file) remove_proc_entry("misc", NULL); return err;}subsys_initcall(misc_init);