drivers/tty/pty.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  Added support for a Unix98-style ptmx device.
   5  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   6  *
   7  *  When reading this code see also fs/devpts. In particular note that the
   8  *  driver_data field is used by the devpts side as a binding to the devpts
   9  *  inode.
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/errno.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/sched.h>
  20 #include <linux/string.h>
  21 #include <linux/major.h>
  22 #include <linux/mm.h>
  23 #include <linux/init.h>
  24 #include <linux/device.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/bitops.h>
  27 #include <linux/devpts_fs.h>
  28 #include <linux/slab.h>
  29 #include <linux/mutex.h>
  30
  31
  32 #ifdef CONFIG_UNIX98_PTYS
  33 static struct tty_driver *ptm_driver;
  34 static struct tty_driver *pts_driver;
  35 static DEFINE_MUTEX(devpts_mutex);
  36 #endif
  37
  38 static void pty_close(struct tty_struct *tty, struct file *filp)
  39 {
  40         BUG_ON(!tty);
  41         if (tty->driver->subtype == PTY_TYPE_MASTER)
  42                 WARN_ON(tty->count > 1);
  43         else {
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         wake_up_interruptible(&tty->read_wait);
  48         wake_up_interruptible(&tty->write_wait);
  49         tty->packet = 0;
  50         /* Review - krefs on tty_link ?? */
  51         if (!tty->link)
  52                 return;
  53         tty->link->packet = 0;
  54         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  55         wake_up_interruptible(&tty->link->read_wait);
  56         wake_up_interruptible(&tty->link->write_wait);
  57         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  58                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  59 #ifdef CONFIG_UNIX98_PTYS
  60                 if (tty->driver == ptm_driver) {
  61                         mutex_lock(&devpts_mutex);
  62                         devpts_pty_kill(tty->link);
  63                         mutex_unlock(&devpts_mutex);
  64                 }
  65 #endif
  66                 tty_unlock(tty);
  67                 tty_vhangup(tty->link);
  68                 tty_lock(tty);
  69         }
  70 }
  71
  72 /*
  73  * The unthrottle routine is called by the line discipline to signal
  74  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  75  * flag is always set, to force the line discipline to always call the
  76  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  77  * characters in the queue.  This is necessary since each time this
  78  * happens, we need to wake up any sleeping processes that could be
  79  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  80  * for the pty buffer to be drained.
  81  */
  82 static void pty_unthrottle(struct tty_struct *tty)
  83 {
  84         tty_wakeup(tty->link);
  85         set_bit(TTY_THROTTLED, &tty->flags);
  86 }
  87
  88 /**
  89  *      pty_space       -       report space left for writing
  90  *      @to: tty we are writing into
  91  *
  92  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  93  *      allows a lot of overspill room for echo and other fun messes to
  94  *      be handled properly
  95  */
  96
  97 static int pty_space(struct tty_struct *to)
  98 {
  99         int n = 8192 - to->buf.memory_used;
 100         if (n < 0)
 101                 return 0;
 102         return n;
 103 }
 104
 105 /**
 106  *      pty_write               -       write to a pty
 107  *      @tty: the tty we write from
 108  *      @buf: kernel buffer of data
 109  *      @count: bytes to write
 110  *
 111  *      Our "hardware" write method. Data is coming from the ldisc which
 112  *      may be in a non sleeping state. We simply throw this at the other
 113  *      end of the link as if we were an IRQ handler receiving stuff for
 114  *      the other side of the pty/tty pair.
 115  */
 116
 117 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 118 {
 119         struct tty_struct *to = tty->link;
 120
 121         if (tty->stopped)
 122                 return 0;
 123
 124         if (c > 0) {
 125                 /* Stuff the data into the input queue of the other end */
 126                 c = tty_insert_flip_string(to, buf, c);
 127                 /* And shovel */
 128                 if (c) {
 129                         tty_flip_buffer_push(to);
 130                         tty_wakeup(tty);
 131                 }
 132         }
 133         return c;
 134 }
 135
 136 /**
 137  *      pty_write_room  -       write space
 138  *      @tty: tty we are writing from
 139  *
 140  *      Report how many bytes the ldisc can send into the queue for
 141  *      the other device.
 142  */
 143
 144 static int pty_write_room(struct tty_struct *tty)
 145 {
 146         if (tty->stopped)
 147                 return 0;
 148         return pty_space(tty->link);
 149 }
 150
 151 /**
 152  *      pty_chars_in_buffer     -       characters currently in our tx queue
 153  *      @tty: our tty
 154  *
 155  *      Report how much we have in the transmit queue. As everything is
 156  *      instantly at the other end this is easy to implement.
 157  */
 158
 159 static int pty_chars_in_buffer(struct tty_struct *tty)
 160 {
 161         return 0;
 162 }
 163
 164 /* Set the lock flag on a pty */
 165 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 166 {
 167         int val;
 168         if (get_user(val, arg))
 169                 return -EFAULT;
 170         if (val)
 171                 set_bit(TTY_PTY_LOCK, &tty->flags);
 172         else
 173                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 174         return 0;
 175 }
 176
 177 /* Send a signal to the slave */
 178 static int pty_signal(struct tty_struct *tty, int sig)
 179 {
 180         unsigned long flags;
 181         struct pid *pgrp;
 182
 183         if (tty->link) {
 184                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 185                 pgrp = get_pid(tty->link->pgrp);
 186                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 187
 188                 kill_pgrp(pgrp, sig, 1);
 189                 put_pid(pgrp);
 190         }
 191         return 0;
 192 }
 193
 194 static void pty_flush_buffer(struct tty_struct *tty)
 195 {
 196         struct tty_struct *to = tty->link;
 197         unsigned long flags;
 198
 199         if (!to)
 200                 return;
 201         /* tty_buffer_flush(to); FIXME */
 202         if (to->packet) {
 203                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 204                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 205                 wake_up_interruptible(&to->read_wait);
 206                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 207         }
 208 }
 209
 210 static int pty_open(struct tty_struct *tty, struct file *filp)
 211 {
 212         int     retval = -ENODEV;
 213
 214         if (!tty || !tty->link)
 215                 goto out;
 216
 217         retval = -EIO;
 218         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 219                 goto out;
 220         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 221                 goto out;
 222         if (tty->link->count != 1)
 223                 goto out;
 224
 225         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 226         set_bit(TTY_THROTTLED, &tty->flags);
 227         retval = 0;
 228 out:
 229         return retval;
 230 }
 231
 232 static void pty_set_termios(struct tty_struct *tty,
 233                                         struct ktermios *old_termios)
 234 {
 235         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 236         tty->termios->c_cflag |= (CS8 | CREAD);
 237 }
 238
 239 /**
 240  *      pty_do_resize           -       resize event
 241  *      @tty: tty being resized
 242  *      @ws: window size being set.
 243  *
 244  *      Update the termios variables and send the necessary signals to
 245  *      peform a terminal resize correctly
 246  */
 247
 248 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 249 {
 250         struct pid *pgrp, *rpgrp;
 251         unsigned long flags;
 252         struct tty_struct *pty = tty->link;
 253
 254         /* For a PTY we need to lock the tty side */
 255         mutex_lock(&tty->termios_mutex);
 256         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 257                 goto done;
 258
 259         /* Get the PID values and reference them so we can
 260            avoid holding the tty ctrl lock while sending signals.
 261            We need to lock these individually however. */
 262
 263         spin_lock_irqsave(&tty->ctrl_lock, flags);
 264         pgrp = get_pid(tty->pgrp);
 265         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 266
 267         spin_lock_irqsave(&pty->ctrl_lock, flags);
 268         rpgrp = get_pid(pty->pgrp);
 269         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 270
 271         if (pgrp)
 272                 kill_pgrp(pgrp, SIGWINCH, 1);
 273         if (rpgrp != pgrp && rpgrp)
 274                 kill_pgrp(rpgrp, SIGWINCH, 1);
 275
 276         put_pid(pgrp);
 277         put_pid(rpgrp);
 278
 279         tty->winsize = *ws;
 280         pty->winsize = *ws;     /* Never used so will go away soon */
 281 done:
 282         mutex_unlock(&tty->termios_mutex);
 283         return 0;
 284 }
 285
 286 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 287                 bool legacy)
 288 {
 289         struct tty_struct *o_tty;
 290         struct tty_port *ports[2];
 291         int idx = tty->index;
 292         int retval = -ENOMEM;
 293
 294         o_tty = alloc_tty_struct();
 295         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 296         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 297         if (!o_tty || !ports[0] || !ports[1])
 298                 goto err_free_tty;
 299         if (!try_module_get(driver->other->owner)) {
 300                 /* This cannot in fact currently happen */
 301                 goto err_free_tty;
 302         }
 303         initialize_tty_struct(o_tty, driver->other, idx);
 304
 305         if (legacy) {
 306                 /* We always use new tty termios data so we can do this
 307                    the easy way .. */
 308                 retval = tty_init_termios(tty);
 309                 if (retval)
 310                         goto err_deinit_tty;
 311
 312                 retval = tty_init_termios(o_tty);
 313                 if (retval)
 314                         goto err_free_termios;
 315
 316                 driver->other->ttys[idx] = o_tty;
 317                 driver->ttys[idx] = tty;
 318         } else {
 319                 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 320                 if (tty->termios == NULL)
 321                         goto err_deinit_tty;
 322                 *tty->termios = driver->init_termios;
 323                 tty->termios_locked = tty->termios + 1;
 324
 325                 o_tty->termios = kzalloc(sizeof(struct ktermios[2]),
 326                                 GFP_KERNEL);
 327                 if (o_tty->termios == NULL)
 328                         goto err_free_termios;
 329                 *o_tty->termios = driver->other->init_termios;
 330                 o_tty->termios_locked = o_tty->termios + 1;
 331         }
 332
 333         /*
 334          * Everything allocated ... set up the o_tty structure.
 335          */
 336         tty_driver_kref_get(driver->other);
 337         if (driver->subtype == PTY_TYPE_MASTER)
 338                 o_tty->count++;
 339         /* Establish the links in both directions */
 340         tty->link   = o_tty;
 341         o_tty->link = tty;
 342         tty_port_init(ports[0]);
 343         tty_port_init(ports[1]);
 344         o_tty->port = ports[0];
 345         tty->port = ports[1];
 346
 347         tty_driver_kref_get(driver);
 348         tty->count++;
 349         return 0;
 350 err_free_termios:
 351         if (legacy)
 352                 tty_free_termios(tty);
 353         else
 354                 kfree(tty->termios);
 355 err_deinit_tty:
 356         deinitialize_tty_struct(o_tty);
 357         module_put(o_tty->driver->owner);
 358 err_free_tty:
 359         kfree(ports[0]);
 360         kfree(ports[1]);
 361         free_tty_struct(o_tty);
 362         return retval;
 363 }
 364
 365 static void pty_cleanup(struct tty_struct *tty)
 366 {
 367         kfree(tty->port);
 368 }
 369
 370 /* Traditional BSD devices */
 371 #ifdef CONFIG_LEGACY_PTYS
 372
 373 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 374 {
 375         return pty_common_install(driver, tty, true);
 376 }
 377
 378 static int pty_bsd_ioctl(struct tty_struct *tty,
 379                          unsigned int cmd, unsigned long arg)
 380 {
 381         switch (cmd) {
 382         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 383                 return pty_set_lock(tty, (int __user *) arg);
 384         case TIOCSIG:    /* Send signal to other side of pty */
 385                 return pty_signal(tty, (int) arg);
 386         }
 387         return -ENOIOCTLCMD;
 388 }
 389
 390 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 391 module_param(legacy_count, int, 0);
 392
 393 /*
 394  * The master side of a pty can do TIOCSPTLCK and thus
 395  * has pty_bsd_ioctl.
 396  */
 397 static const struct tty_operations master_pty_ops_bsd = {
 398         .install = pty_install,
 399         .open = pty_open,
 400         .close = pty_close,
 401         .write = pty_write,
 402         .write_room = pty_write_room,
 403         .flush_buffer = pty_flush_buffer,
 404         .chars_in_buffer = pty_chars_in_buffer,
 405         .unthrottle = pty_unthrottle,
 406         .set_termios = pty_set_termios,
 407         .ioctl = pty_bsd_ioctl,
 408         .cleanup = pty_cleanup,
 409         .resize = pty_resize
 410 };
 411
 412 static const struct tty_operations slave_pty_ops_bsd = {
 413         .install = pty_install,
 414         .open = pty_open,
 415         .close = pty_close,
 416         .write = pty_write,
 417         .write_room = pty_write_room,
 418         .flush_buffer = pty_flush_buffer,
 419         .chars_in_buffer = pty_chars_in_buffer,
 420         .unthrottle = pty_unthrottle,
 421         .set_termios = pty_set_termios,
 422         .cleanup = pty_cleanup,
 423         .resize = pty_resize
 424 };
 425
 426 static void __init legacy_pty_init(void)
 427 {
 428         struct tty_driver *pty_driver, *pty_slave_driver;
 429
 430         if (legacy_count <= 0)
 431                 return;
 432
 433         pty_driver = alloc_tty_driver(legacy_count);
 434         if (!pty_driver)
 435                 panic("Couldn't allocate pty driver");
 436
 437         pty_slave_driver = alloc_tty_driver(legacy_count);
 438         if (!pty_slave_driver)
 439                 panic("Couldn't allocate pty slave driver");
 440
 441         pty_driver->driver_name = "pty_master";
 442         pty_driver->name = "pty";
 443         pty_driver->major = PTY_MASTER_MAJOR;
 444         pty_driver->minor_start = 0;
 445         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 446         pty_driver->subtype = PTY_TYPE_MASTER;
 447         pty_driver->init_termios = tty_std_termios;
 448         pty_driver->init_termios.c_iflag = 0;
 449         pty_driver->init_termios.c_oflag = 0;
 450         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 451         pty_driver->init_termios.c_lflag = 0;
 452         pty_driver->init_termios.c_ispeed = 38400;
 453         pty_driver->init_termios.c_ospeed = 38400;
 454         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 455         pty_driver->other = pty_slave_driver;
 456         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 457
 458         pty_slave_driver->driver_name = "pty_slave";
 459         pty_slave_driver->name = "ttyp";
 460         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 461         pty_slave_driver->minor_start = 0;
 462         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 463         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 464         pty_slave_driver->init_termios = tty_std_termios;
 465         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 466         pty_slave_driver->init_termios.c_ispeed = 38400;
 467         pty_slave_driver->init_termios.c_ospeed = 38400;
 468         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 469                                         TTY_DRIVER_REAL_RAW;
 470         pty_slave_driver->other = pty_driver;
 471         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 472
 473         if (tty_register_driver(pty_driver))
 474                 panic("Couldn't register pty driver");
 475         if (tty_register_driver(pty_slave_driver))
 476                 panic("Couldn't register pty slave driver");
 477 }
 478 #else
 479 static inline void legacy_pty_init(void) { }
 480 #endif
 481
 482 /* Unix98 devices */
 483 #ifdef CONFIG_UNIX98_PTYS
 484
 485 static struct cdev ptmx_cdev;
 486
 487 static int pty_unix98_ioctl(struct tty_struct *tty,
 488                             unsigned int cmd, unsigned long arg)
 489 {
 490         switch (cmd) {
 491         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 492                 return pty_set_lock(tty, (int __user *)arg);
 493         case TIOCGPTN: /* Get PT Number */
 494                 return put_user(tty->index, (unsigned int __user *)arg);
 495         case TIOCSIG:    /* Send signal to other side of pty */
 496                 return pty_signal(tty, (int) arg);
 497         }
 498
 499         return -ENOIOCTLCMD;
 500 }
 501
 502 /**
 503  *      ptm_unix98_lookup       -       find a pty master
 504  *      @driver: ptm driver
 505  *      @idx: tty index
 506  *
 507  *      Look up a pty master device. Called under the tty_mutex for now.
 508  *      This provides our locking.
 509  */
 510
 511 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 512                 struct inode *ptm_inode, int idx)
 513 {
 514         /* Master must be open via /dev/ptmx */
 515         return ERR_PTR(-EIO);
 516 }
 517
 518 /**
 519  *      pts_unix98_lookup       -       find a pty slave
 520  *      @driver: pts driver
 521  *      @idx: tty index
 522  *
 523  *      Look up a pty master device. Called under the tty_mutex for now.
 524  *      This provides our locking for the tty pointer.
 525  */
 526
 527 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 528                 struct inode *pts_inode, int idx)
 529 {
 530         struct tty_struct *tty;
 531
 532         mutex_lock(&devpts_mutex);
 533         tty = devpts_get_tty(pts_inode, idx);
 534         mutex_unlock(&devpts_mutex);
 535         /* Master must be open before slave */
 536         if (!tty)
 537                 return ERR_PTR(-EIO);
 538         return tty;
 539 }
 540
 541 static void pty_unix98_shutdown(struct tty_struct *tty)
 542 {
 543         tty_driver_remove_tty(tty->driver, tty);
 544         /* We have our own method as we don't use the tty index */
 545         kfree(tty->termios);
 546 }
 547
 548 /* We have no need to install and remove our tty objects as devpts does all
 549    the work for us */
 550
 551 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 552 {
 553         return pty_common_install(driver, tty, false);
 554 }
 555
 556 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 557 {
 558 }
 559
 560 static const struct tty_operations ptm_unix98_ops = {
 561         .lookup = ptm_unix98_lookup,
 562         .install = pty_unix98_install,
 563         .remove = pty_unix98_remove,
 564         .open = pty_open,
 565         .close = pty_close,
 566         .write = pty_write,
 567         .write_room = pty_write_room,
 568         .flush_buffer = pty_flush_buffer,
 569         .chars_in_buffer = pty_chars_in_buffer,
 570         .unthrottle = pty_unthrottle,
 571         .set_termios = pty_set_termios,
 572         .ioctl = pty_unix98_ioctl,
 573         .shutdown = pty_unix98_shutdown,
 574         .cleanup = pty_cleanup,
 575         .resize = pty_resize
 576 };
 577
 578 static const struct tty_operations pty_unix98_ops = {
 579         .lookup = pts_unix98_lookup,
 580         .install = pty_unix98_install,
 581         .remove = pty_unix98_remove,
 582         .open = pty_open,
 583         .close = pty_close,
 584         .write = pty_write,
 585         .write_room = pty_write_room,
 586         .flush_buffer = pty_flush_buffer,
 587         .chars_in_buffer = pty_chars_in_buffer,
 588         .unthrottle = pty_unthrottle,
 589         .set_termios = pty_set_termios,
 590         .shutdown = pty_unix98_shutdown,
 591         .cleanup = pty_cleanup,
 592 };
 593
 594 /**
 595  *      ptmx_open               -       open a unix 98 pty master
 596  *      @inode: inode of device file
 597  *      @filp: file pointer to tty
 598  *
 599  *      Allocate a unix98 pty master device from the ptmx driver.
 600  *
 601  *      Locking: tty_mutex protects the init_dev work. tty->count should
 602  *              protect the rest.
 603  *              allocated_ptys_lock handles the list of free pty numbers
 604  */
 605
 606 static int ptmx_open(struct inode *inode, struct file *filp)
 607 {
 608         struct tty_struct *tty;
 609         int retval;
 610         int index;
 611
 612         nonseekable_open(inode, filp);
 613
 614         retval = tty_alloc_file(filp);
 615         if (retval)
 616                 return retval;
 617
 618         /* find a device that is not in use. */
 619         mutex_lock(&devpts_mutex);
 620         index = devpts_new_index(inode);
 621         mutex_unlock(&devpts_mutex);
 622         if (index < 0) {
 623                 retval = index;
 624                 goto err_file;
 625         }
 626
 627         mutex_lock(&tty_mutex);
 628         tty = tty_init_dev(ptm_driver, index);
 629
 630         if (IS_ERR(tty)) {
 631                 retval = PTR_ERR(tty);
 632                 goto out;
 633         }
 634
 635         /* The tty returned here is locked so we can safely
 636            drop the mutex */
 637         mutex_unlock(&tty_mutex);
 638
 639         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 640
 641         tty_add_file(tty, filp);
 642
 643         retval = devpts_pty_new(inode, tty->link);
 644         if (retval)
 645                 goto err_release;
 646
 647         retval = ptm_driver->ops->open(tty, filp);
 648         if (retval)
 649                 goto err_release;
 650
 651         tty_unlock(tty);
 652         return 0;
 653 err_release:
 654         tty_unlock(tty);
 655         tty_release(inode, filp);
 656         return retval;
 657 out:
 658         mutex_unlock(&tty_mutex);
 659         devpts_kill_index(inode, index);
 660 err_file:
 661         tty_free_file(filp);
 662         return retval;
 663 }
 664
 665 static struct file_operations ptmx_fops;
 666
 667 static void __init unix98_pty_init(void)
 668 {
 669         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 670         if (!ptm_driver)
 671                 panic("Couldn't allocate Unix98 ptm driver");
 672         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 673         if (!pts_driver)
 674                 panic("Couldn't allocate Unix98 pts driver");
 675
 676         ptm_driver->driver_name = "pty_master";
 677         ptm_driver->name = "ptm";
 678         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 679         ptm_driver->minor_start = 0;
 680         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 681         ptm_driver->subtype = PTY_TYPE_MASTER;
 682         ptm_driver->init_termios = tty_std_termios;
 683         ptm_driver->init_termios.c_iflag = 0;
 684         ptm_driver->init_termios.c_oflag = 0;
 685         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 686         ptm_driver->init_termios.c_lflag = 0;
 687         ptm_driver->init_termios.c_ispeed = 38400;
 688         ptm_driver->init_termios.c_ospeed = 38400;
 689         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 690                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 691         ptm_driver->other = pts_driver;
 692         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 693
 694         pts_driver->driver_name = "pty_slave";
 695         pts_driver->name = "pts";
 696         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 697         pts_driver->minor_start = 0;
 698         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 699         pts_driver->subtype = PTY_TYPE_SLAVE;
 700         pts_driver->init_termios = tty_std_termios;
 701         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 702         pts_driver->init_termios.c_ispeed = 38400;
 703         pts_driver->init_termios.c_ospeed = 38400;
 704         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 705                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 706         pts_driver->other = ptm_driver;
 707         tty_set_operations(pts_driver, &pty_unix98_ops);
 708
 709         if (tty_register_driver(ptm_driver))
 710                 panic("Couldn't register Unix98 ptm driver");
 711         if (tty_register_driver(pts_driver))
 712                 panic("Couldn't register Unix98 pts driver");
 713
 714         /* Now create the /dev/ptmx special device */
 715         tty_default_fops(&ptmx_fops);
 716         ptmx_fops.open = ptmx_open;
 717
 718         cdev_init(&ptmx_cdev, &ptmx_fops);
 719         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 720             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 721                 panic("Couldn't register /dev/ptmx driver\n");
 722         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 723 }
 724
 725 #else
 726 static inline void unix98_pty_init(void) { }
 727 #endif
 728
 729 static int __init pty_init(void)
 730 {
 731         legacy_pty_init();
 732         unix98_pty_init();
 733         return 0;
 734 }
 735 module_init(pty_init);