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 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 286                 bool legacy)
 287 {
 288         struct tty_struct *o_tty;
 289         struct tty_port *ports[2];
 290         int idx = tty->index;
 291         int retval = -ENOMEM;
 292
 293         o_tty = alloc_tty_struct();
 294         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 295         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 296         if (!o_tty || !ports[0] || !ports[1])
 297                 goto err_free_tty;
 298         if (!try_module_get(driver->other->owner)) {
 299                 /* This cannot in fact currently happen */
 300                 goto err_free_tty;
 301         }
 302         initialize_tty_struct(o_tty, driver->other, idx);
 303
 304         if (legacy) {
 305                 /* We always use new tty termios data so we can do this
 306                    the easy way .. */
 307                 retval = tty_init_termios(tty);
 308                 if (retval)
 309                         goto err_deinit_tty;
 310
 311                 retval = tty_init_termios(o_tty);
 312                 if (retval)
 313                         goto err_free_termios;
 314
 315                 driver->other->ttys[idx] = o_tty;
 316                 driver->ttys[idx] = tty;
 317         } else {
 318                 tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 319                 if (tty->termios == NULL)
 320                         goto err_deinit_tty;
 321                 *tty->termios = driver->init_termios;
 322                 tty->termios_locked = tty->termios + 1;
 323
 324                 o_tty->termios = kzalloc(sizeof(struct ktermios[2]),
 325                                 GFP_KERNEL);
 326                 if (o_tty->termios == NULL)
 327                         goto err_free_termios;
 328                 *o_tty->termios = driver->other->init_termios;
 329                 o_tty->termios_locked = o_tty->termios + 1;
 330         }
 331
 332         /*
 333          * Everything allocated ... set up the o_tty structure.
 334          */
 335         tty_driver_kref_get(driver->other);
 336         if (driver->subtype == PTY_TYPE_MASTER)
 337                 o_tty->count++;
 338         /* Establish the links in both directions */
 339         tty->link   = o_tty;
 340         o_tty->link = tty;
 341         tty_port_init(ports[0]);
 342         tty_port_init(ports[1]);
 343         o_tty->port = ports[0];
 344         tty->port = ports[1];
 345
 346         tty_driver_kref_get(driver);
 347         tty->count++;
 348         return 0;
 349 err_free_termios:
 350         if (legacy)
 351                 tty_free_termios(tty);
 352         else
 353                 kfree(tty->termios);
 354 err_deinit_tty:
 355         deinitialize_tty_struct(o_tty);
 356         module_put(o_tty->driver->owner);
 357 err_free_tty:
 358         kfree(ports[0]);
 359         kfree(ports[1]);
 360         free_tty_struct(o_tty);
 361         return retval;
 362 }
 363
 364 static void pty_cleanup(struct tty_struct *tty)
 365 {
 366         kfree(tty->port);
 367 }
 368
 369 /* Traditional BSD devices */
 370 #ifdef CONFIG_LEGACY_PTYS
 371
 372 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 373 {
 374         return pty_common_install(driver, tty, true);
 375 }
 376
 377 static int pty_bsd_ioctl(struct tty_struct *tty,
 378                          unsigned int cmd, unsigned long arg)
 379 {
 380         switch (cmd) {
 381         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 382                 return pty_set_lock(tty, (int __user *) arg);
 383         case TIOCSIG:    /* Send signal to other side of pty */
 384                 return pty_signal(tty, (int) arg);
 385         }
 386         return -ENOIOCTLCMD;
 387 }
 388
 389 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 390 module_param(legacy_count, int, 0);
 391
 392 /*
 393  * The master side of a pty can do TIOCSPTLCK and thus
 394  * has pty_bsd_ioctl.
 395  */
 396 static const struct tty_operations master_pty_ops_bsd = {
 397         .install = pty_install,
 398         .open = pty_open,
 399         .close = pty_close,
 400         .write = pty_write,
 401         .write_room = pty_write_room,
 402         .flush_buffer = pty_flush_buffer,
 403         .chars_in_buffer = pty_chars_in_buffer,
 404         .unthrottle = pty_unthrottle,
 405         .set_termios = pty_set_termios,
 406         .ioctl = pty_bsd_ioctl,
 407         .cleanup = pty_cleanup,
 408         .resize = pty_resize
 409 };
 410
 411 static const struct tty_operations slave_pty_ops_bsd = {
 412         .install = pty_install,
 413         .open = pty_open,
 414         .close = pty_close,
 415         .write = pty_write,
 416         .write_room = pty_write_room,
 417         .flush_buffer = pty_flush_buffer,
 418         .chars_in_buffer = pty_chars_in_buffer,
 419         .unthrottle = pty_unthrottle,
 420         .set_termios = pty_set_termios,
 421         .cleanup = pty_cleanup,
 422         .resize = pty_resize
 423 };
 424
 425 static void __init legacy_pty_init(void)
 426 {
 427         struct tty_driver *pty_driver, *pty_slave_driver;
 428
 429         if (legacy_count <= 0)
 430                 return;
 431
 432         pty_driver = alloc_tty_driver(legacy_count);
 433         if (!pty_driver)
 434                 panic("Couldn't allocate pty driver");
 435
 436         pty_slave_driver = alloc_tty_driver(legacy_count);
 437         if (!pty_slave_driver)
 438                 panic("Couldn't allocate pty slave driver");
 439
 440         pty_driver->driver_name = "pty_master";
 441         pty_driver->name = "pty";
 442         pty_driver->major = PTY_MASTER_MAJOR;
 443         pty_driver->minor_start = 0;
 444         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 445         pty_driver->subtype = PTY_TYPE_MASTER;
 446         pty_driver->init_termios = tty_std_termios;
 447         pty_driver->init_termios.c_iflag = 0;
 448         pty_driver->init_termios.c_oflag = 0;
 449         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 450         pty_driver->init_termios.c_lflag = 0;
 451         pty_driver->init_termios.c_ispeed = 38400;
 452         pty_driver->init_termios.c_ospeed = 38400;
 453         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 454         pty_driver->other = pty_slave_driver;
 455         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 456
 457         pty_slave_driver->driver_name = "pty_slave";
 458         pty_slave_driver->name = "ttyp";
 459         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 460         pty_slave_driver->minor_start = 0;
 461         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 462         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 463         pty_slave_driver->init_termios = tty_std_termios;
 464         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 465         pty_slave_driver->init_termios.c_ispeed = 38400;
 466         pty_slave_driver->init_termios.c_ospeed = 38400;
 467         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 468                                         TTY_DRIVER_REAL_RAW;
 469         pty_slave_driver->other = pty_driver;
 470         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 471
 472         if (tty_register_driver(pty_driver))
 473                 panic("Couldn't register pty driver");
 474         if (tty_register_driver(pty_slave_driver))
 475                 panic("Couldn't register pty slave driver");
 476 }
 477 #else
 478 static inline void legacy_pty_init(void) { }
 479 #endif
 480
 481 /* Unix98 devices */
 482 #ifdef CONFIG_UNIX98_PTYS
 483
 484 static struct cdev ptmx_cdev;
 485
 486 static int pty_unix98_ioctl(struct tty_struct *tty,
 487                             unsigned int cmd, unsigned long arg)
 488 {
 489         switch (cmd) {
 490         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 491                 return pty_set_lock(tty, (int __user *)arg);
 492         case TIOCGPTN: /* Get PT Number */
 493                 return put_user(tty->index, (unsigned int __user *)arg);
 494         case TIOCSIG:    /* Send signal to other side of pty */
 495                 return pty_signal(tty, (int) arg);
 496         }
 497
 498         return -ENOIOCTLCMD;
 499 }
 500
 501 /**
 502  *      ptm_unix98_lookup       -       find a pty master
 503  *      @driver: ptm driver
 504  *      @idx: tty index
 505  *
 506  *      Look up a pty master device. Called under the tty_mutex for now.
 507  *      This provides our locking.
 508  */
 509
 510 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 511                 struct inode *ptm_inode, int idx)
 512 {
 513         /* Master must be open via /dev/ptmx */
 514         return ERR_PTR(-EIO);
 515 }
 516
 517 /**
 518  *      pts_unix98_lookup       -       find a pty slave
 519  *      @driver: pts driver
 520  *      @idx: tty index
 521  *
 522  *      Look up a pty master device. Called under the tty_mutex for now.
 523  *      This provides our locking for the tty pointer.
 524  */
 525
 526 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 527                 struct inode *pts_inode, int idx)
 528 {
 529         struct tty_struct *tty;
 530
 531         mutex_lock(&devpts_mutex);
 532         tty = devpts_get_tty(pts_inode, idx);
 533         mutex_unlock(&devpts_mutex);
 534         /* Master must be open before slave */
 535         if (!tty)
 536                 return ERR_PTR(-EIO);
 537         return tty;
 538 }
 539
 540 static void pty_unix98_shutdown(struct tty_struct *tty)
 541 {
 542         tty_driver_remove_tty(tty->driver, tty);
 543         /* We have our own method as we don't use the tty index */
 544         kfree(tty->termios);
 545 }
 546
 547 /* We have no need to install and remove our tty objects as devpts does all
 548    the work for us */
 549
 550 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 551 {
 552         return pty_common_install(driver, tty, false);
 553 }
 554
 555 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 556 {
 557 }
 558
 559 static const struct tty_operations ptm_unix98_ops = {
 560         .lookup = ptm_unix98_lookup,
 561         .install = pty_unix98_install,
 562         .remove = pty_unix98_remove,
 563         .open = pty_open,
 564         .close = pty_close,
 565         .write = pty_write,
 566         .write_room = pty_write_room,
 567         .flush_buffer = pty_flush_buffer,
 568         .chars_in_buffer = pty_chars_in_buffer,
 569         .unthrottle = pty_unthrottle,
 570         .set_termios = pty_set_termios,
 571         .ioctl = pty_unix98_ioctl,
 572         .shutdown = pty_unix98_shutdown,
 573         .cleanup = pty_cleanup,
 574         .resize = pty_resize
 575 };
 576
 577 static const struct tty_operations pty_unix98_ops = {
 578         .lookup = pts_unix98_lookup,
 579         .install = pty_unix98_install,
 580         .remove = pty_unix98_remove,
 581         .open = pty_open,
 582         .close = pty_close,
 583         .write = pty_write,
 584         .write_room = pty_write_room,
 585         .flush_buffer = pty_flush_buffer,
 586         .chars_in_buffer = pty_chars_in_buffer,
 587         .unthrottle = pty_unthrottle,
 588         .set_termios = pty_set_termios,
 589         .shutdown = pty_unix98_shutdown,
 590         .cleanup = pty_cleanup,
 591 };
 592
 593 /**
 594  *      ptmx_open               -       open a unix 98 pty master
 595  *      @inode: inode of device file
 596  *      @filp: file pointer to tty
 597  *
 598  *      Allocate a unix98 pty master device from the ptmx driver.
 599  *
 600  *      Locking: tty_mutex protects the init_dev work. tty->count should
 601  *              protect the rest.
 602  *              allocated_ptys_lock handles the list of free pty numbers
 603  */
 604
 605 static int ptmx_open(struct inode *inode, struct file *filp)
 606 {
 607         struct tty_struct *tty;
 608         int retval;
 609         int index;
 610
 611         nonseekable_open(inode, filp);
 612
 613         retval = tty_alloc_file(filp);
 614         if (retval)
 615                 return retval;
 616
 617         /* find a device that is not in use. */
 618         tty_lock();
 619         index = devpts_new_index(inode);
 620         tty_unlock();
 621         if (index < 0) {
 622                 retval = index;
 623                 goto err_file;
 624         }
 625
 626         mutex_lock(&tty_mutex);
 627         mutex_lock(&devpts_mutex);
 628         tty = tty_init_dev(ptm_driver, index);
 629         mutex_unlock(&devpts_mutex);
 630         tty_lock();
 631         mutex_unlock(&tty_mutex);
 632
 633         if (IS_ERR(tty)) {
 634                 retval = PTR_ERR(tty);
 635                 goto out;
 636         }
 637
 638         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 639
 640         tty_add_file(tty, filp);
 641
 642         retval = devpts_pty_new(inode, tty->link);
 643         if (retval)
 644                 goto err_release;
 645
 646         retval = ptm_driver->ops->open(tty, filp);
 647         if (retval)
 648                 goto err_release;
 649
 650         tty_unlock();
 651         return 0;
 652 err_release:
 653         tty_unlock();
 654         tty_release(inode, filp);
 655         return retval;
 656 out:
 657         devpts_kill_index(inode, index);
 658         tty_unlock();
 659 err_file:
 660         tty_free_file(filp);
 661         return retval;
 662 }
 663
 664 static struct file_operations ptmx_fops;
 665
 666 static void __init unix98_pty_init(void)
 667 {
 668         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 669         if (!ptm_driver)
 670                 panic("Couldn't allocate Unix98 ptm driver");
 671         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 672         if (!pts_driver)
 673                 panic("Couldn't allocate Unix98 pts driver");
 674
 675         ptm_driver->driver_name = "pty_master";
 676         ptm_driver->name = "ptm";
 677         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 678         ptm_driver->minor_start = 0;
 679         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 680         ptm_driver->subtype = PTY_TYPE_MASTER;
 681         ptm_driver->init_termios = tty_std_termios;
 682         ptm_driver->init_termios.c_iflag = 0;
 683         ptm_driver->init_termios.c_oflag = 0;
 684         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 685         ptm_driver->init_termios.c_lflag = 0;
 686         ptm_driver->init_termios.c_ispeed = 38400;
 687         ptm_driver->init_termios.c_ospeed = 38400;
 688         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 689                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 690         ptm_driver->other = pts_driver;
 691         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 692
 693         pts_driver->driver_name = "pty_slave";
 694         pts_driver->name = "pts";
 695         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 696         pts_driver->minor_start = 0;
 697         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 698         pts_driver->subtype = PTY_TYPE_SLAVE;
 699         pts_driver->init_termios = tty_std_termios;
 700         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 701         pts_driver->init_termios.c_ispeed = 38400;
 702         pts_driver->init_termios.c_ospeed = 38400;
 703         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 704                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 705         pts_driver->other = ptm_driver;
 706         tty_set_operations(pts_driver, &pty_unix98_ops);
 707
 708         if (tty_register_driver(ptm_driver))
 709                 panic("Couldn't register Unix98 ptm driver");
 710         if (tty_register_driver(pts_driver))
 711                 panic("Couldn't register Unix98 pts driver");
 712
 713         /* Now create the /dev/ptmx special device */
 714         tty_default_fops(&ptmx_fops);
 715         ptmx_fops.open = ptmx_open;
 716
 717         cdev_init(&ptmx_cdev, &ptmx_fops);
 718         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 719             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 720                 panic("Couldn't register /dev/ptmx driver\n");
 721         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 722 }
 723
 724 #else
 725 static inline void unix98_pty_init(void) { }
 726 #endif
 727
 728 static int __init pty_init(void)
 729 {
 730         legacy_pty_init();
 731         unix98_pty_init();
 732         return 0;
 733 }
 734 module_init(pty_init);