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         if (!tty->link)
  51                 return;
  52         tty->link->packet = 0;
  53         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  54         wake_up_interruptible(&tty->link->read_wait);
  55         wake_up_interruptible(&tty->link->write_wait);
  56         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  57                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  58 #ifdef CONFIG_UNIX98_PTYS
  59                 if (tty->driver == ptm_driver) {
  60                         mutex_lock(&devpts_mutex);
  61                         devpts_pty_kill(tty->link);
  62                         mutex_unlock(&devpts_mutex);
  63                 }
  64 #endif
  65                 tty_unlock();
  66                 tty_vhangup(tty->link);
  67                 tty_lock();
  68         }
  69 }
  70
  71 /*
  72  * The unthrottle routine is called by the line discipline to signal
  73  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  74  * flag is always set, to force the line discipline to always call the
  75  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  76  * characters in the queue.  This is necessary since each time this
  77  * happens, we need to wake up any sleeping processes that could be
  78  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  79  * for the pty buffer to be drained.
  80  */
  81 static void pty_unthrottle(struct tty_struct *tty)
  82 {
  83         tty_wakeup(tty->link);
  84         set_bit(TTY_THROTTLED, &tty->flags);
  85 }
  86
  87 /**
  88  *      pty_space       -       report space left for writing
  89  *      @to: tty we are writing into
  90  *
  91  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  92  *      allows a lot of overspill room for echo and other fun messes to
  93  *      be handled properly
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = 8192 - to->buf.memory_used;
  99         if (n < 0)
 100                 return 0;
 101         return n;
 102 }
 103
 104 /**
 105  *      pty_write               -       write to a pty
 106  *      @tty: the tty we write from
 107  *      @buf: kernel buffer of data
 108  *      @count: bytes to write
 109  *
 110  *      Our "hardware" write method. Data is coming from the ldisc which
 111  *      may be in a non sleeping state. We simply throw this at the other
 112  *      end of the link as if we were an IRQ handler receiving stuff for
 113  *      the other side of the pty/tty pair.
 114  */
 115
 116 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 117 {
 118         struct tty_struct *to = tty->link;
 119
 120         if (tty->stopped)
 121                 return 0;
 122
 123         if (c > 0) {
 124                 /* Stuff the data into the input queue of the other end */
 125                 c = tty_insert_flip_string(to, buf, c);
 126                 /* And shovel */
 127                 if (c) {
 128                         tty_flip_buffer_push(to);
 129                         tty_wakeup(tty);
 130                 }
 131         }
 132         return c;
 133 }
 134
 135 /**
 136  *      pty_write_room  -       write space
 137  *      @tty: tty we are writing from
 138  *
 139  *      Report how many bytes the ldisc can send into the queue for
 140  *      the other device.
 141  */
 142
 143 static int pty_write_room(struct tty_struct *tty)
 144 {
 145         if (tty->stopped)
 146                 return 0;
 147         return pty_space(tty->link);
 148 }
 149
 150 /**
 151  *      pty_chars_in_buffer     -       characters currently in our tx queue
 152  *      @tty: our tty
 153  *
 154  *      Report how much we have in the transmit queue. As everything is
 155  *      instantly at the other end this is easy to implement.
 156  */
 157
 158 static int pty_chars_in_buffer(struct tty_struct *tty)
 159 {
 160         return 0;
 161 }
 162
 163 /* Set the lock flag on a pty */
 164 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 165 {
 166         int val;
 167         if (get_user(val, arg))
 168                 return -EFAULT;
 169         if (val)
 170                 set_bit(TTY_PTY_LOCK, &tty->flags);
 171         else
 172                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 173         return 0;
 174 }
 175
 176 /* Send a signal to the slave */
 177 static int pty_signal(struct tty_struct *tty, int sig)
 178 {
 179         unsigned long flags;
 180         struct pid *pgrp;
 181
 182         if (tty->link) {
 183                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 184                 pgrp = get_pid(tty->link->pgrp);
 185                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 186
 187                 kill_pgrp(pgrp, sig, 1);
 188                 put_pid(pgrp);
 189         }
 190         return 0;
 191 }
 192
 193 static void pty_flush_buffer(struct tty_struct *tty)
 194 {
 195         struct tty_struct *to = tty->link;
 196         unsigned long flags;
 197
 198         if (!to)
 199                 return;
 200         /* tty_buffer_flush(to); FIXME */
 201         if (to->packet) {
 202                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 203                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 204                 wake_up_interruptible(&to->read_wait);
 205                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 206         }
 207 }
 208
 209 static int pty_open(struct tty_struct *tty, struct file *filp)
 210 {
 211         int     retval = -ENODEV;
 212
 213         if (!tty || !tty->link)
 214                 goto out;
 215
 216         retval = -EIO;
 217         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 218                 goto out;
 219         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 220                 goto out;
 221         if (tty->link->count != 1)
 222                 goto out;
 223
 224         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 225         set_bit(TTY_THROTTLED, &tty->flags);
 226         retval = 0;
 227 out:
 228         return retval;
 229 }
 230
 231 static void pty_set_termios(struct tty_struct *tty,
 232                                         struct ktermios *old_termios)
 233 {
 234         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 235         tty->termios->c_cflag |= (CS8 | CREAD);
 236 }
 237
 238 /**
 239  *      pty_do_resize           -       resize event
 240  *      @tty: tty being resized
 241  *      @ws: window size being set.
 242  *
 243  *      Update the termios variables and send the necessary signals to
 244  *      peform a terminal resize correctly
 245  */
 246
 247 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 248 {
 249         struct pid *pgrp, *rpgrp;
 250         unsigned long flags;
 251         struct tty_struct *pty = tty->link;
 252
 253         /* For a PTY we need to lock the tty side */
 254         mutex_lock(&tty->termios_mutex);
 255         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 256                 goto done;
 257
 258         /* Get the PID values and reference them so we can
 259            avoid holding the tty ctrl lock while sending signals.
 260            We need to lock these individually however. */
 261
 262         spin_lock_irqsave(&tty->ctrl_lock, flags);
 263         pgrp = get_pid(tty->pgrp);
 264         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 265
 266         spin_lock_irqsave(&pty->ctrl_lock, flags);
 267         rpgrp = get_pid(pty->pgrp);
 268         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 269
 270         if (pgrp)
 271                 kill_pgrp(pgrp, SIGWINCH, 1);
 272         if (rpgrp != pgrp && rpgrp)
 273                 kill_pgrp(rpgrp, SIGWINCH, 1);
 274
 275         put_pid(pgrp);
 276         put_pid(rpgrp);
 277
 278         tty->winsize = *ws;
 279         pty->winsize = *ws;     /* Never used so will go away soon */
 280 done:
 281         mutex_unlock(&tty->termios_mutex);
 282         return 0;
 283 }
 284
 285 /* Traditional BSD devices */
 286 #ifdef CONFIG_LEGACY_PTYS
 287
 288 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 289 {
 290         struct tty_struct *o_tty;
 291         int idx = tty->index;
 292         int retval;
 293
 294         o_tty = alloc_tty_struct();
 295         if (!o_tty)
 296                 return -ENOMEM;
 297         if (!try_module_get(driver->other->owner)) {
 298                 /* This cannot in fact currently happen */
 299                 retval = -ENOMEM;
 300                 goto err_free_tty;
 301         }
 302         initialize_tty_struct(o_tty, driver->other, idx);
 303
 304         /* We always use new tty termios data so we can do this
 305            the easy way .. */
 306         retval = tty_init_termios(tty);
 307         if (retval)
 308                 goto err_deinit_tty;
 309
 310         retval = tty_init_termios(o_tty);
 311         if (retval)
 312                 goto err_free_termios;
 313
 314         /*
 315          * Everything allocated ... set up the o_tty structure.
 316          */
 317         driver->other->ttys[idx] = o_tty;
 318         tty_driver_kref_get(driver->other);
 319         if (driver->subtype == PTY_TYPE_MASTER)
 320                 o_tty->count++;
 321         /* Establish the links in both directions */
 322         tty->link   = o_tty;
 323         o_tty->link = tty;
 324
 325         tty_driver_kref_get(driver);
 326         tty->count++;
 327         driver->ttys[idx] = tty;
 328         return 0;
 329 err_free_termios:
 330         tty_free_termios(tty);
 331 err_deinit_tty:
 332         deinitialize_tty_struct(o_tty);
 333         module_put(o_tty->driver->owner);
 334 err_free_tty:
 335         free_tty_struct(o_tty);
 336         return retval;
 337 }
 338
 339 static int pty_bsd_ioctl(struct tty_struct *tty,
 340                          unsigned int cmd, unsigned long arg)
 341 {
 342         switch (cmd) {
 343         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 344                 return pty_set_lock(tty, (int __user *) arg);
 345         case TIOCSIG:    /* Send signal to other side of pty */
 346                 return pty_signal(tty, (int) arg);
 347         }
 348         return -ENOIOCTLCMD;
 349 }
 350
 351 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 352 module_param(legacy_count, int, 0);
 353
 354 /*
 355  * The master side of a pty can do TIOCSPTLCK and thus
 356  * has pty_bsd_ioctl.
 357  */
 358 static const struct tty_operations master_pty_ops_bsd = {
 359         .install = pty_install,
 360         .open = pty_open,
 361         .close = pty_close,
 362         .write = pty_write,
 363         .write_room = pty_write_room,
 364         .flush_buffer = pty_flush_buffer,
 365         .chars_in_buffer = pty_chars_in_buffer,
 366         .unthrottle = pty_unthrottle,
 367         .set_termios = pty_set_termios,
 368         .ioctl = pty_bsd_ioctl,
 369         .resize = pty_resize
 370 };
 371
 372 static const struct tty_operations slave_pty_ops_bsd = {
 373         .install = pty_install,
 374         .open = pty_open,
 375         .close = pty_close,
 376         .write = pty_write,
 377         .write_room = pty_write_room,
 378         .flush_buffer = pty_flush_buffer,
 379         .chars_in_buffer = pty_chars_in_buffer,
 380         .unthrottle = pty_unthrottle,
 381         .set_termios = pty_set_termios,
 382         .resize = pty_resize
 383 };
 384
 385 static void __init legacy_pty_init(void)
 386 {
 387         struct tty_driver *pty_driver, *pty_slave_driver;
 388
 389         if (legacy_count <= 0)
 390                 return;
 391
 392         pty_driver = alloc_tty_driver(legacy_count);
 393         if (!pty_driver)
 394                 panic("Couldn't allocate pty driver");
 395
 396         pty_slave_driver = alloc_tty_driver(legacy_count);
 397         if (!pty_slave_driver)
 398                 panic("Couldn't allocate pty slave driver");
 399
 400         pty_driver->driver_name = "pty_master";
 401         pty_driver->name = "pty";
 402         pty_driver->major = PTY_MASTER_MAJOR;
 403         pty_driver->minor_start = 0;
 404         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 405         pty_driver->subtype = PTY_TYPE_MASTER;
 406         pty_driver->init_termios = tty_std_termios;
 407         pty_driver->init_termios.c_iflag = 0;
 408         pty_driver->init_termios.c_oflag = 0;
 409         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 410         pty_driver->init_termios.c_lflag = 0;
 411         pty_driver->init_termios.c_ispeed = 38400;
 412         pty_driver->init_termios.c_ospeed = 38400;
 413         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 414         pty_driver->other = pty_slave_driver;
 415         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 416
 417         pty_slave_driver->driver_name = "pty_slave";
 418         pty_slave_driver->name = "ttyp";
 419         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 420         pty_slave_driver->minor_start = 0;
 421         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 422         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 423         pty_slave_driver->init_termios = tty_std_termios;
 424         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 425         pty_slave_driver->init_termios.c_ispeed = 38400;
 426         pty_slave_driver->init_termios.c_ospeed = 38400;
 427         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 428                                         TTY_DRIVER_REAL_RAW;
 429         pty_slave_driver->other = pty_driver;
 430         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 431
 432         if (tty_register_driver(pty_driver))
 433                 panic("Couldn't register pty driver");
 434         if (tty_register_driver(pty_slave_driver))
 435                 panic("Couldn't register pty slave driver");
 436 }
 437 #else
 438 static inline void legacy_pty_init(void) { }
 439 #endif
 440
 441 /* Unix98 devices */
 442 #ifdef CONFIG_UNIX98_PTYS
 443
 444 static struct cdev ptmx_cdev;
 445
 446 static int pty_unix98_ioctl(struct tty_struct *tty,
 447                             unsigned int cmd, unsigned long arg)
 448 {
 449         switch (cmd) {
 450         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 451                 return pty_set_lock(tty, (int __user *)arg);
 452         case TIOCGPTN: /* Get PT Number */
 453                 return put_user(tty->index, (unsigned int __user *)arg);
 454         case TIOCSIG:    /* Send signal to other side of pty */
 455                 return pty_signal(tty, (int) arg);
 456         }
 457
 458         return -ENOIOCTLCMD;
 459 }
 460
 461 /**
 462  *      ptm_unix98_lookup       -       find a pty master
 463  *      @driver: ptm driver
 464  *      @idx: tty index
 465  *
 466  *      Look up a pty master device. Called under the tty_mutex for now.
 467  *      This provides our locking.
 468  */
 469
 470 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 471                 struct inode *ptm_inode, int idx)
 472 {
 473         /* Master must be open via /dev/ptmx */
 474         return ERR_PTR(-EIO);
 475 }
 476
 477 /**
 478  *      pts_unix98_lookup       -       find a pty slave
 479  *      @driver: pts driver
 480  *      @idx: tty index
 481  *
 482  *      Look up a pty master device. Called under the tty_mutex for now.
 483  *      This provides our locking for the tty pointer.
 484  */
 485
 486 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 487                 struct inode *pts_inode, int idx)
 488 {
 489         struct tty_struct *tty;
 490
 491         mutex_lock(&devpts_mutex);
 492         tty = devpts_get_tty(pts_inode, idx);
 493         mutex_unlock(&devpts_mutex);
 494         /* Master must be open before slave */
 495         if (!tty)
 496                 return ERR_PTR(-EIO);
 497         return tty;
 498 }
 499
 500 static void pty_unix98_shutdown(struct tty_struct *tty)
 501 {
 502         tty_driver_remove_tty(tty->driver, tty);
 503         /* We have our own method as we don't use the tty index */
 504         kfree(tty->termios);
 505 }
 506
 507 /* We have no need to install and remove our tty objects as devpts does all
 508    the work for us */
 509
 510 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 511 {
 512         struct tty_struct *o_tty;
 513         int idx = tty->index;
 514
 515         o_tty = alloc_tty_struct();
 516         if (!o_tty)
 517                 return -ENOMEM;
 518         if (!try_module_get(driver->other->owner)) {
 519                 /* This cannot in fact currently happen */
 520                 goto err_free_tty;
 521         }
 522         initialize_tty_struct(o_tty, driver->other, idx);
 523
 524         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 525         if (tty->termios == NULL)
 526                 goto err_free_mem;
 527         *tty->termios = driver->init_termios;
 528         tty->termios_locked = tty->termios + 1;
 529
 530         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 531         if (o_tty->termios == NULL)
 532                 goto err_free_mem;
 533         *o_tty->termios = driver->other->init_termios;
 534         o_tty->termios_locked = o_tty->termios + 1;
 535
 536         tty_driver_kref_get(driver->other);
 537         if (driver->subtype == PTY_TYPE_MASTER)
 538                 o_tty->count++;
 539         /* Establish the links in both directions */
 540         tty->link   = o_tty;
 541         o_tty->link = tty;
 542         /*
 543          * All structures have been allocated, so now we install them.
 544          * Failures after this point use release_tty to clean up, so
 545          * there's no need to null out the local pointers.
 546          */
 547         tty_driver_kref_get(driver);
 548         tty->count++;
 549         return 0;
 550 err_free_mem:
 551         deinitialize_tty_struct(o_tty);
 552         kfree(o_tty->termios);
 553         kfree(tty->termios);
 554         module_put(o_tty->driver->owner);
 555 err_free_tty:
 556         free_tty_struct(o_tty);
 557         return -ENOMEM;
 558 }
 559
 560 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 561 {
 562 }
 563
 564 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 565 {
 566 }
 567
 568 static const struct tty_operations ptm_unix98_ops = {
 569         .lookup = ptm_unix98_lookup,
 570         .install = pty_unix98_install,
 571         .remove = ptm_unix98_remove,
 572         .open = pty_open,
 573         .close = pty_close,
 574         .write = pty_write,
 575         .write_room = pty_write_room,
 576         .flush_buffer = pty_flush_buffer,
 577         .chars_in_buffer = pty_chars_in_buffer,
 578         .unthrottle = pty_unthrottle,
 579         .set_termios = pty_set_termios,
 580         .ioctl = pty_unix98_ioctl,
 581         .shutdown = pty_unix98_shutdown,
 582         .resize = pty_resize
 583 };
 584
 585 static const struct tty_operations pty_unix98_ops = {
 586         .lookup = pts_unix98_lookup,
 587         .install = pty_unix98_install,
 588         .remove = pts_unix98_remove,
 589         .open = pty_open,
 590         .close = pty_close,
 591         .write = pty_write,
 592         .write_room = pty_write_room,
 593         .flush_buffer = pty_flush_buffer,
 594         .chars_in_buffer = pty_chars_in_buffer,
 595         .unthrottle = pty_unthrottle,
 596         .set_termios = pty_set_termios,
 597         .shutdown = pty_unix98_shutdown
 598 };
 599
 600 /**
 601  *      ptmx_open               -       open a unix 98 pty master
 602  *      @inode: inode of device file
 603  *      @filp: file pointer to tty
 604  *
 605  *      Allocate a unix98 pty master device from the ptmx driver.
 606  *
 607  *      Locking: tty_mutex protects the init_dev work. tty->count should
 608  *              protect the rest.
 609  *              allocated_ptys_lock handles the list of free pty numbers
 610  */
 611
 612 static int ptmx_open(struct inode *inode, struct file *filp)
 613 {
 614         struct tty_struct *tty;
 615         int retval;
 616         int index;
 617
 618         nonseekable_open(inode, filp);
 619
 620         retval = tty_alloc_file(filp);
 621         if (retval)
 622                 return retval;
 623
 624         /* find a device that is not in use. */
 625         tty_lock();
 626         index = devpts_new_index(inode);
 627         tty_unlock();
 628         if (index < 0) {
 629                 retval = index;
 630                 goto err_file;
 631         }
 632
 633         mutex_lock(&tty_mutex);
 634         mutex_lock(&devpts_mutex);
 635         tty = tty_init_dev(ptm_driver, index);
 636         mutex_unlock(&devpts_mutex);
 637         tty_lock();
 638         mutex_unlock(&tty_mutex);
 639
 640         if (IS_ERR(tty)) {
 641                 retval = PTR_ERR(tty);
 642                 goto out;
 643         }
 644
 645         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 646
 647         tty_add_file(tty, filp);
 648
 649         retval = devpts_pty_new(inode, tty->link);
 650         if (retval)
 651                 goto err_release;
 652
 653         retval = ptm_driver->ops->open(tty, filp);
 654         if (retval)
 655                 goto err_release;
 656
 657         tty_unlock();
 658         return 0;
 659 err_release:
 660         tty_unlock();
 661         tty_release(inode, filp);
 662         return retval;
 663 out:
 664         devpts_kill_index(inode, index);
 665         tty_unlock();
 666 err_file:
 667         tty_free_file(filp);
 668         return retval;
 669 }
 670
 671 static struct file_operations ptmx_fops;
 672
 673 static void __init unix98_pty_init(void)
 674 {
 675         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 676         if (!ptm_driver)
 677                 panic("Couldn't allocate Unix98 ptm driver");
 678         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 679         if (!pts_driver)
 680                 panic("Couldn't allocate Unix98 pts driver");
 681
 682         ptm_driver->driver_name = "pty_master";
 683         ptm_driver->name = "ptm";
 684         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 685         ptm_driver->minor_start = 0;
 686         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 687         ptm_driver->subtype = PTY_TYPE_MASTER;
 688         ptm_driver->init_termios = tty_std_termios;
 689         ptm_driver->init_termios.c_iflag = 0;
 690         ptm_driver->init_termios.c_oflag = 0;
 691         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 692         ptm_driver->init_termios.c_lflag = 0;
 693         ptm_driver->init_termios.c_ispeed = 38400;
 694         ptm_driver->init_termios.c_ospeed = 38400;
 695         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 696                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 697         ptm_driver->other = pts_driver;
 698         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 699
 700         pts_driver->driver_name = "pty_slave";
 701         pts_driver->name = "pts";
 702         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 703         pts_driver->minor_start = 0;
 704         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 705         pts_driver->subtype = PTY_TYPE_SLAVE;
 706         pts_driver->init_termios = tty_std_termios;
 707         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 708         pts_driver->init_termios.c_ispeed = 38400;
 709         pts_driver->init_termios.c_ospeed = 38400;
 710         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 711                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 712         pts_driver->other = ptm_driver;
 713         tty_set_operations(pts_driver, &pty_unix98_ops);
 714
 715         if (tty_register_driver(ptm_driver))
 716                 panic("Couldn't register Unix98 ptm driver");
 717         if (tty_register_driver(pts_driver))
 718                 panic("Couldn't register Unix98 pts driver");
 719
 720         /* Now create the /dev/ptmx special device */
 721         tty_default_fops(&ptmx_fops);
 722         ptmx_fops.open = ptmx_open;
 723
 724         cdev_init(&ptmx_cdev, &ptmx_fops);
 725         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 726             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 727                 panic("Couldn't register /dev/ptmx driver\n");
 728         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 729 }
 730
 731 #else
 732 static inline void unix98_pty_init(void) { }
 733 #endif
 734
 735 static int __init pty_init(void)
 736 {
 737         legacy_pty_init();
 738         unix98_pty_init();
 739         return 0;
 740 }
 741 module_init(pty_init);