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 /**
 287  *      pty_common_install              -       set up the pty pair
 288  *      @driver: the pty driver
 289  *      @tty: the tty being instantiated
 290  *      @bool: legacy, true if this is BSD style
 291  *
 292  *      Perform the initial set up for the tty/pty pair. Called from the
 293  *      tty layer when the port is first opened.
 294  *
 295  *      Locking: the caller must hold the tty_mutex
 296  */
 297 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 298                 bool legacy)
 299 {
 300         struct tty_struct *o_tty;
 301         struct tty_port *ports[2];
 302         int idx = tty->index;
 303         int retval = -ENOMEM;
 304
 305         o_tty = alloc_tty_struct();
 306         if (!o_tty)
 307                 goto err;
 308         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 309         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 310         if (!ports[0] || !ports[1])
 311                 goto err_free_tty;
 312         if (!try_module_get(driver->other->owner)) {
 313                 /* This cannot in fact currently happen */
 314                 goto err_free_tty;
 315         }
 316         initialize_tty_struct(o_tty, driver->other, idx);
 317
 318         if (legacy) {
 319                 /* We always use new tty termios data so we can do this
 320                    the easy way .. */
 321                 retval = tty_init_termios(tty);
 322                 if (retval)
 323                         goto err_deinit_tty;
 324
 325                 retval = tty_init_termios(o_tty);
 326                 if (retval)
 327                         goto err_free_termios;
 328
 329                 driver->other->ttys[idx] = o_tty;
 330                 driver->ttys[idx] = tty;
 331         } else {
 332                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 333                 tty->termios = driver->init_termios;
 334                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 335                 o_tty->termios = driver->other->init_termios;
 336         }
 337
 338         /*
 339          * Everything allocated ... set up the o_tty structure.
 340          */
 341         tty_driver_kref_get(driver->other);
 342         if (driver->subtype == PTY_TYPE_MASTER)
 343                 o_tty->count++;
 344         /* Establish the links in both directions */
 345         tty->link   = o_tty;
 346         o_tty->link = tty;
 347         tty_port_init(ports[0]);
 348         tty_port_init(ports[1]);
 349         o_tty->port = ports[0];
 350         tty->port = ports[1];
 351
 352         tty_driver_kref_get(driver);
 353         tty->count++;
 354         return 0;
 355 err_free_termios:
 356         if (legacy)
 357                 tty_free_termios(tty);
 358 err_deinit_tty:
 359         deinitialize_tty_struct(o_tty);
 360         module_put(o_tty->driver->owner);
 361 err_free_tty:
 362         kfree(ports[0]);
 363         kfree(ports[1]);
 364         free_tty_struct(o_tty);
 365 err:
 366         return retval;
 367 }
 368
 369 static void pty_cleanup(struct tty_struct *tty)
 370 {
 371         kfree(tty->port);
 372 }
 373
 374 /* Traditional BSD devices */
 375 #ifdef CONFIG_LEGACY_PTYS
 376
 377 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 378 {
 379         return pty_common_install(driver, tty, true);
 380 }
 381
 382 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 383 {
 384         struct tty_struct *pair = tty->link;
 385         driver->ttys[tty->index] = NULL;
 386         if (pair)
 387                 pair->driver->ttys[pair->index] = NULL;
 388 }
 389
 390 static int pty_bsd_ioctl(struct tty_struct *tty,
 391                          unsigned int cmd, unsigned long arg)
 392 {
 393         switch (cmd) {
 394         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 395                 return pty_set_lock(tty, (int __user *) arg);
 396         case TIOCSIG:    /* Send signal to other side of pty */
 397                 return pty_signal(tty, (int) arg);
 398         }
 399         return -ENOIOCTLCMD;
 400 }
 401
 402 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 403 module_param(legacy_count, int, 0);
 404
 405 /*
 406  * The master side of a pty can do TIOCSPTLCK and thus
 407  * has pty_bsd_ioctl.
 408  */
 409 static const struct tty_operations master_pty_ops_bsd = {
 410         .install = pty_install,
 411         .open = pty_open,
 412         .close = pty_close,
 413         .write = pty_write,
 414         .write_room = pty_write_room,
 415         .flush_buffer = pty_flush_buffer,
 416         .chars_in_buffer = pty_chars_in_buffer,
 417         .unthrottle = pty_unthrottle,
 418         .set_termios = pty_set_termios,
 419         .ioctl = pty_bsd_ioctl,
 420         .cleanup = pty_cleanup,
 421         .resize = pty_resize,
 422         .remove = pty_remove
 423 };
 424
 425 static const struct tty_operations slave_pty_ops_bsd = {
 426         .install = pty_install,
 427         .open = pty_open,
 428         .close = pty_close,
 429         .write = pty_write,
 430         .write_room = pty_write_room,
 431         .flush_buffer = pty_flush_buffer,
 432         .chars_in_buffer = pty_chars_in_buffer,
 433         .unthrottle = pty_unthrottle,
 434         .set_termios = pty_set_termios,
 435         .cleanup = pty_cleanup,
 436         .resize = pty_resize,
 437         .remove = pty_remove
 438 };
 439
 440 static void __init legacy_pty_init(void)
 441 {
 442         struct tty_driver *pty_driver, *pty_slave_driver;
 443
 444         if (legacy_count <= 0)
 445                 return;
 446
 447         pty_driver = alloc_tty_driver(legacy_count);
 448         if (!pty_driver)
 449                 panic("Couldn't allocate pty driver");
 450
 451         pty_slave_driver = alloc_tty_driver(legacy_count);
 452         if (!pty_slave_driver)
 453                 panic("Couldn't allocate pty slave driver");
 454
 455         pty_driver->driver_name = "pty_master";
 456         pty_driver->name = "pty";
 457         pty_driver->major = PTY_MASTER_MAJOR;
 458         pty_driver->minor_start = 0;
 459         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 460         pty_driver->subtype = PTY_TYPE_MASTER;
 461         pty_driver->init_termios = tty_std_termios;
 462         pty_driver->init_termios.c_iflag = 0;
 463         pty_driver->init_termios.c_oflag = 0;
 464         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 465         pty_driver->init_termios.c_lflag = 0;
 466         pty_driver->init_termios.c_ispeed = 38400;
 467         pty_driver->init_termios.c_ospeed = 38400;
 468         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 469         pty_driver->other = pty_slave_driver;
 470         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 471
 472         pty_slave_driver->driver_name = "pty_slave";
 473         pty_slave_driver->name = "ttyp";
 474         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 475         pty_slave_driver->minor_start = 0;
 476         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 477         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 478         pty_slave_driver->init_termios = tty_std_termios;
 479         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 480         pty_slave_driver->init_termios.c_ispeed = 38400;
 481         pty_slave_driver->init_termios.c_ospeed = 38400;
 482         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 483                                         TTY_DRIVER_REAL_RAW;
 484         pty_slave_driver->other = pty_driver;
 485         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 486
 487         if (tty_register_driver(pty_driver))
 488                 panic("Couldn't register pty driver");
 489         if (tty_register_driver(pty_slave_driver))
 490                 panic("Couldn't register pty slave driver");
 491 }
 492 #else
 493 static inline void legacy_pty_init(void) { }
 494 #endif
 495
 496 /* Unix98 devices */
 497 #ifdef CONFIG_UNIX98_PTYS
 498
 499 static struct cdev ptmx_cdev;
 500
 501 static int pty_unix98_ioctl(struct tty_struct *tty,
 502                             unsigned int cmd, unsigned long arg)
 503 {
 504         switch (cmd) {
 505         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 506                 return pty_set_lock(tty, (int __user *)arg);
 507         case TIOCGPTN: /* Get PT Number */
 508                 return put_user(tty->index, (unsigned int __user *)arg);
 509         case TIOCSIG:    /* Send signal to other side of pty */
 510                 return pty_signal(tty, (int) arg);
 511         }
 512
 513         return -ENOIOCTLCMD;
 514 }
 515
 516 /**
 517  *      ptm_unix98_lookup       -       find a pty master
 518  *      @driver: ptm driver
 519  *      @idx: tty index
 520  *
 521  *      Look up a pty master device. Called under the tty_mutex for now.
 522  *      This provides our locking.
 523  */
 524
 525 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 526                 struct inode *ptm_inode, int idx)
 527 {
 528         /* Master must be open via /dev/ptmx */
 529         return ERR_PTR(-EIO);
 530 }
 531
 532 /**
 533  *      pts_unix98_lookup       -       find a pty slave
 534  *      @driver: pts driver
 535  *      @idx: tty index
 536  *
 537  *      Look up a pty master device. Called under the tty_mutex for now.
 538  *      This provides our locking for the tty pointer.
 539  */
 540
 541 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 542                 struct inode *pts_inode, int idx)
 543 {
 544         struct tty_struct *tty;
 545
 546         mutex_lock(&devpts_mutex);
 547         tty = devpts_get_tty(pts_inode, idx);
 548         mutex_unlock(&devpts_mutex);
 549         /* Master must be open before slave */
 550         if (!tty)
 551                 return ERR_PTR(-EIO);
 552         return tty;
 553 }
 554
 555 /* We have no need to install and remove our tty objects as devpts does all
 556    the work for us */
 557
 558 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 559 {
 560         return pty_common_install(driver, tty, false);
 561 }
 562
 563 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 564 {
 565 }
 566
 567 static const struct tty_operations ptm_unix98_ops = {
 568         .lookup = ptm_unix98_lookup,
 569         .install = pty_unix98_install,
 570         .remove = pty_unix98_remove,
 571         .open = pty_open,
 572         .close = pty_close,
 573         .write = pty_write,
 574         .write_room = pty_write_room,
 575         .flush_buffer = pty_flush_buffer,
 576         .chars_in_buffer = pty_chars_in_buffer,
 577         .unthrottle = pty_unthrottle,
 578         .set_termios = pty_set_termios,
 579         .ioctl = pty_unix98_ioctl,
 580         .resize = pty_resize,
 581         .cleanup = pty_cleanup
 582 };
 583
 584 static const struct tty_operations pty_unix98_ops = {
 585         .lookup = pts_unix98_lookup,
 586         .install = pty_unix98_install,
 587         .remove = pty_unix98_remove,
 588         .open = pty_open,
 589         .close = pty_close,
 590         .write = pty_write,
 591         .write_room = pty_write_room,
 592         .flush_buffer = pty_flush_buffer,
 593         .chars_in_buffer = pty_chars_in_buffer,
 594         .unthrottle = pty_unthrottle,
 595         .set_termios = pty_set_termios,
 596         .cleanup = pty_cleanup,
 597 };
 598
 599 /**
 600  *      ptmx_open               -       open a unix 98 pty master
 601  *      @inode: inode of device file
 602  *      @filp: file pointer to tty
 603  *
 604  *      Allocate a unix98 pty master device from the ptmx driver.
 605  *
 606  *      Locking: tty_mutex protects the init_dev work. tty->count should
 607  *              protect the rest.
 608  *              allocated_ptys_lock handles the list of free pty numbers
 609  */
 610
 611 static int ptmx_open(struct inode *inode, struct file *filp)
 612 {
 613         struct tty_struct *tty;
 614         int retval;
 615         int index;
 616
 617         nonseekable_open(inode, filp);
 618
 619         retval = tty_alloc_file(filp);
 620         if (retval)
 621                 return retval;
 622
 623         /* find a device that is not in use. */
 624         mutex_lock(&devpts_mutex);
 625         index = devpts_new_index(inode);
 626         if (index < 0) {
 627                 retval = index;
 628                 goto err_file;
 629         }
 630
 631         mutex_unlock(&devpts_mutex);
 632
 633         mutex_lock(&tty_mutex);
 634         tty = tty_init_dev(ptm_driver, index);
 635
 636         if (IS_ERR(tty)) {
 637                 retval = PTR_ERR(tty);
 638                 goto out;
 639         }
 640
 641         /* The tty returned here is locked so we can safely
 642            drop the mutex */
 643         mutex_unlock(&tty_mutex);
 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(tty);
 658         return 0;
 659 err_release:
 660         tty_unlock(tty);
 661         tty_release(inode, filp);
 662         return retval;
 663 out:
 664         mutex_unlock(&tty_mutex);
 665         devpts_kill_index(inode, index);
 666 err_file:
 667         mutex_unlock(&devpts_mutex);
 668         tty_free_file(filp);
 669         return retval;
 670 }
 671
 672 static struct file_operations ptmx_fops;
 673
 674 static void __init unix98_pty_init(void)
 675 {
 676         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 677         if (!ptm_driver)
 678                 panic("Couldn't allocate Unix98 ptm driver");
 679         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 680         if (!pts_driver)
 681                 panic("Couldn't allocate Unix98 pts driver");
 682
 683         ptm_driver->driver_name = "pty_master";
 684         ptm_driver->name = "ptm";
 685         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 686         ptm_driver->minor_start = 0;
 687         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 688         ptm_driver->subtype = PTY_TYPE_MASTER;
 689         ptm_driver->init_termios = tty_std_termios;
 690         ptm_driver->init_termios.c_iflag = 0;
 691         ptm_driver->init_termios.c_oflag = 0;
 692         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 693         ptm_driver->init_termios.c_lflag = 0;
 694         ptm_driver->init_termios.c_ispeed = 38400;
 695         ptm_driver->init_termios.c_ospeed = 38400;
 696         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 697                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 698         ptm_driver->other = pts_driver;
 699         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 700
 701         pts_driver->driver_name = "pty_slave";
 702         pts_driver->name = "pts";
 703         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 704         pts_driver->minor_start = 0;
 705         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 706         pts_driver->subtype = PTY_TYPE_SLAVE;
 707         pts_driver->init_termios = tty_std_termios;
 708         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 709         pts_driver->init_termios.c_ispeed = 38400;
 710         pts_driver->init_termios.c_ospeed = 38400;
 711         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 712                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 713         pts_driver->other = ptm_driver;
 714         tty_set_operations(pts_driver, &pty_unix98_ops);
 715
 716         if (tty_register_driver(ptm_driver))
 717                 panic("Couldn't register Unix98 ptm driver");
 718         if (tty_register_driver(pts_driver))
 719                 panic("Couldn't register Unix98 pts driver");
 720
 721         /* Now create the /dev/ptmx special device */
 722         tty_default_fops(&ptmx_fops);
 723         ptmx_fops.open = ptmx_open;
 724
 725         cdev_init(&ptmx_cdev, &ptmx_fops);
 726         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 727             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 728                 panic("Couldn't register /dev/ptmx driver\n");
 729         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 730 }
 731
 732 #else
 733 static inline void unix98_pty_init(void) { }
 734 #endif
 735
 736 static int __init pty_init(void)
 737 {
 738         legacy_pty_init();
 739         unix98_pty_init();
 740         return 0;
 741 }
 742 module_init(pty_init);