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
  30
  31 #ifdef CONFIG_UNIX98_PTYS
  32 static struct tty_driver *ptm_driver;
  33 static struct tty_driver *pts_driver;
  34 #endif
  35
  36 static void pty_close(struct tty_struct *tty, struct file *filp)
  37 {
  38         BUG_ON(!tty);
  39         if (tty->driver->subtype == PTY_TYPE_MASTER)
  40                 WARN_ON(tty->count > 1);
  41         else {
  42                 if (tty->count > 2)
  43                         return;
  44         }
  45         wake_up_interruptible(&tty->read_wait);
  46         wake_up_interruptible(&tty->write_wait);
  47         tty->packet = 0;
  48         if (!tty->link)
  49                 return;
  50         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  51         wake_up_interruptible(&tty->link->read_wait);
  52         wake_up_interruptible(&tty->link->write_wait);
  53         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  54                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  55 #ifdef CONFIG_UNIX98_PTYS
  56                 if (tty->driver == ptm_driver)
  57                         devpts_pty_kill(tty->link);
  58 #endif
  59                 tty_unlock();
  60                 tty_vhangup(tty->link);
  61                 tty_lock();
  62         }
  63 }
  64
  65 /*
  66  * The unthrottle routine is called by the line discipline to signal
  67  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  68  * flag is always set, to force the line discipline to always call the
  69  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  70  * characters in the queue.  This is necessary since each time this
  71  * happens, we need to wake up any sleeping processes that could be
  72  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  73  * for the pty buffer to be drained.
  74  */
  75 static void pty_unthrottle(struct tty_struct *tty)
  76 {
  77         tty_wakeup(tty->link);
  78         set_bit(TTY_THROTTLED, &tty->flags);
  79 }
  80
  81 /**
  82  *      pty_space       -       report space left for writing
  83  *      @to: tty we are writing into
  84  *
  85  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  86  *      allows a lot of overspill room for echo and other fun messes to
  87  *      be handled properly
  88  */
  89
  90 static int pty_space(struct tty_struct *to)
  91 {
  92         int n = 8192 - to->buf.memory_used;
  93         if (n < 0)
  94                 return 0;
  95         return n;
  96 }
  97
  98 /**
  99  *      pty_write               -       write to a pty
 100  *      @tty: the tty we write from
 101  *      @buf: kernel buffer of data
 102  *      @count: bytes to write
 103  *
 104  *      Our "hardware" write method. Data is coming from the ldisc which
 105  *      may be in a non sleeping state. We simply throw this at the other
 106  *      end of the link as if we were an IRQ handler receiving stuff for
 107  *      the other side of the pty/tty pair.
 108  */
 109
 110 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 111 {
 112         struct tty_struct *to = tty->link;
 113
 114         if (tty->stopped)
 115                 return 0;
 116
 117         if (c > 0) {
 118                 /* Stuff the data into the input queue of the other end */
 119                 c = tty_insert_flip_string(to, buf, c);
 120                 /* And shovel */
 121                 if (c) {
 122                         tty_flip_buffer_push(to);
 123                         tty_wakeup(tty);
 124                 }
 125         }
 126         return c;
 127 }
 128
 129 /**
 130  *      pty_write_room  -       write space
 131  *      @tty: tty we are writing from
 132  *
 133  *      Report how many bytes the ldisc can send into the queue for
 134  *      the other device.
 135  */
 136
 137 static int pty_write_room(struct tty_struct *tty)
 138 {
 139         if (tty->stopped)
 140                 return 0;
 141         return pty_space(tty->link);
 142 }
 143
 144 /**
 145  *      pty_chars_in_buffer     -       characters currently in our tx queue
 146  *      @tty: our tty
 147  *
 148  *      Report how much we have in the transmit queue. As everything is
 149  *      instantly at the other end this is easy to implement.
 150  */
 151
 152 static int pty_chars_in_buffer(struct tty_struct *tty)
 153 {
 154         return 0;
 155 }
 156
 157 /* Set the lock flag on a pty */
 158 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 159 {
 160         int val;
 161         if (get_user(val, arg))
 162                 return -EFAULT;
 163         if (val)
 164                 set_bit(TTY_PTY_LOCK, &tty->flags);
 165         else
 166                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 167         return 0;
 168 }
 169
 170 /* Send a signal to the slave */
 171 static int pty_signal(struct tty_struct *tty, int sig)
 172 {
 173         unsigned long flags;
 174         struct pid *pgrp;
 175
 176         if (tty->link) {
 177                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 178                 pgrp = get_pid(tty->link->pgrp);
 179                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 180
 181                 kill_pgrp(pgrp, sig, 1);
 182                 put_pid(pgrp);
 183         }
 184         return 0;
 185 }
 186
 187 static void pty_flush_buffer(struct tty_struct *tty)
 188 {
 189         struct tty_struct *to = tty->link;
 190         unsigned long flags;
 191
 192         if (!to)
 193                 return;
 194         /* tty_buffer_flush(to); FIXME */
 195         if (to->packet) {
 196                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 197                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 198                 wake_up_interruptible(&to->read_wait);
 199                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 200         }
 201 }
 202
 203 static int pty_open(struct tty_struct *tty, struct file *filp)
 204 {
 205         int     retval = -ENODEV;
 206
 207         if (!tty || !tty->link)
 208                 goto out;
 209
 210         retval = -EIO;
 211         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 212                 goto out;
 213         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 214                 goto out;
 215         if (tty->link->count != 1)
 216                 goto out;
 217
 218         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 219         set_bit(TTY_THROTTLED, &tty->flags);
 220         retval = 0;
 221 out:
 222         return retval;
 223 }
 224
 225 static void pty_set_termios(struct tty_struct *tty,
 226                                         struct ktermios *old_termios)
 227 {
 228         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 229         tty->termios->c_cflag |= (CS8 | CREAD);
 230 }
 231
 232 /**
 233  *      pty_do_resize           -       resize event
 234  *      @tty: tty being resized
 235  *      @ws: window size being set.
 236  *
 237  *      Update the termios variables and send the necessary signals to
 238  *      peform a terminal resize correctly
 239  */
 240
 241 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 242 {
 243         struct pid *pgrp, *rpgrp;
 244         unsigned long flags;
 245         struct tty_struct *pty = tty->link;
 246
 247         /* For a PTY we need to lock the tty side */
 248         mutex_lock(&tty->termios_mutex);
 249         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 250                 goto done;
 251
 252         /* Get the PID values and reference them so we can
 253            avoid holding the tty ctrl lock while sending signals.
 254            We need to lock these individually however. */
 255
 256         spin_lock_irqsave(&tty->ctrl_lock, flags);
 257         pgrp = get_pid(tty->pgrp);
 258         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 259
 260         spin_lock_irqsave(&pty->ctrl_lock, flags);
 261         rpgrp = get_pid(pty->pgrp);
 262         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 263
 264         if (pgrp)
 265                 kill_pgrp(pgrp, SIGWINCH, 1);
 266         if (rpgrp != pgrp && rpgrp)
 267                 kill_pgrp(rpgrp, SIGWINCH, 1);
 268
 269         put_pid(pgrp);
 270         put_pid(rpgrp);
 271
 272         tty->winsize = *ws;
 273         pty->winsize = *ws;     /* Never used so will go away soon */
 274 done:
 275         mutex_unlock(&tty->termios_mutex);
 276         return 0;
 277 }
 278
 279 /* Traditional BSD devices */
 280 #ifdef CONFIG_LEGACY_PTYS
 281
 282 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 283 {
 284         struct tty_struct *o_tty;
 285         int idx = tty->index;
 286         int retval;
 287
 288         o_tty = alloc_tty_struct();
 289         if (!o_tty)
 290                 return -ENOMEM;
 291         if (!try_module_get(driver->other->owner)) {
 292                 /* This cannot in fact currently happen */
 293                 retval = -ENOMEM;
 294                 goto err_free_tty;
 295         }
 296         initialize_tty_struct(o_tty, driver->other, idx);
 297
 298         /* We always use new tty termios data so we can do this
 299            the easy way .. */
 300         retval = tty_init_termios(tty);
 301         if (retval)
 302                 goto err_deinit_tty;
 303
 304         retval = tty_init_termios(o_tty);
 305         if (retval)
 306                 goto err_free_termios;
 307
 308         /*
 309          * Everything allocated ... set up the o_tty structure.
 310          */
 311         driver->other->ttys[idx] = o_tty;
 312         tty_driver_kref_get(driver->other);
 313         if (driver->subtype == PTY_TYPE_MASTER)
 314                 o_tty->count++;
 315         /* Establish the links in both directions */
 316         tty->link   = o_tty;
 317         o_tty->link = tty;
 318
 319         tty_driver_kref_get(driver);
 320         tty->count++;
 321         driver->ttys[idx] = tty;
 322         return 0;
 323 err_free_termios:
 324         tty_free_termios(tty);
 325 err_deinit_tty:
 326         deinitialize_tty_struct(o_tty);
 327         module_put(o_tty->driver->owner);
 328 err_free_tty:
 329         free_tty_struct(o_tty);
 330         return retval;
 331 }
 332
 333 static int pty_bsd_ioctl(struct tty_struct *tty,
 334                          unsigned int cmd, unsigned long arg)
 335 {
 336         switch (cmd) {
 337         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 338                 return pty_set_lock(tty, (int __user *) arg);
 339         case TIOCSIG:    /* Send signal to other side of pty */
 340                 return pty_signal(tty, (int) arg);
 341         }
 342         return -ENOIOCTLCMD;
 343 }
 344
 345 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 346 module_param(legacy_count, int, 0);
 347
 348 /*
 349  * The master side of a pty can do TIOCSPTLCK and thus
 350  * has pty_bsd_ioctl.
 351  */
 352 static const struct tty_operations master_pty_ops_bsd = {
 353         .install = pty_install,
 354         .open = pty_open,
 355         .close = pty_close,
 356         .write = pty_write,
 357         .write_room = pty_write_room,
 358         .flush_buffer = pty_flush_buffer,
 359         .chars_in_buffer = pty_chars_in_buffer,
 360         .unthrottle = pty_unthrottle,
 361         .set_termios = pty_set_termios,
 362         .ioctl = pty_bsd_ioctl,
 363         .resize = pty_resize
 364 };
 365
 366 static const struct tty_operations slave_pty_ops_bsd = {
 367         .install = pty_install,
 368         .open = pty_open,
 369         .close = pty_close,
 370         .write = pty_write,
 371         .write_room = pty_write_room,
 372         .flush_buffer = pty_flush_buffer,
 373         .chars_in_buffer = pty_chars_in_buffer,
 374         .unthrottle = pty_unthrottle,
 375         .set_termios = pty_set_termios,
 376         .resize = pty_resize
 377 };
 378
 379 static void __init legacy_pty_init(void)
 380 {
 381         struct tty_driver *pty_driver, *pty_slave_driver;
 382
 383         if (legacy_count <= 0)
 384                 return;
 385
 386         pty_driver = alloc_tty_driver(legacy_count);
 387         if (!pty_driver)
 388                 panic("Couldn't allocate pty driver");
 389
 390         pty_slave_driver = alloc_tty_driver(legacy_count);
 391         if (!pty_slave_driver)
 392                 panic("Couldn't allocate pty slave driver");
 393
 394         pty_driver->driver_name = "pty_master";
 395         pty_driver->name = "pty";
 396         pty_driver->major = PTY_MASTER_MAJOR;
 397         pty_driver->minor_start = 0;
 398         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 399         pty_driver->subtype = PTY_TYPE_MASTER;
 400         pty_driver->init_termios = tty_std_termios;
 401         pty_driver->init_termios.c_iflag = 0;
 402         pty_driver->init_termios.c_oflag = 0;
 403         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 404         pty_driver->init_termios.c_lflag = 0;
 405         pty_driver->init_termios.c_ispeed = 38400;
 406         pty_driver->init_termios.c_ospeed = 38400;
 407         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 408         pty_driver->other = pty_slave_driver;
 409         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 410
 411         pty_slave_driver->driver_name = "pty_slave";
 412         pty_slave_driver->name = "ttyp";
 413         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 414         pty_slave_driver->minor_start = 0;
 415         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 416         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 417         pty_slave_driver->init_termios = tty_std_termios;
 418         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 419         pty_slave_driver->init_termios.c_ispeed = 38400;
 420         pty_slave_driver->init_termios.c_ospeed = 38400;
 421         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 422                                         TTY_DRIVER_REAL_RAW;
 423         pty_slave_driver->other = pty_driver;
 424         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 425
 426         if (tty_register_driver(pty_driver))
 427                 panic("Couldn't register pty driver");
 428         if (tty_register_driver(pty_slave_driver))
 429                 panic("Couldn't register pty slave driver");
 430 }
 431 #else
 432 static inline void legacy_pty_init(void) { }
 433 #endif
 434
 435 /* Unix98 devices */
 436 #ifdef CONFIG_UNIX98_PTYS
 437
 438 static struct cdev ptmx_cdev;
 439
 440 static int pty_unix98_ioctl(struct tty_struct *tty,
 441                             unsigned int cmd, unsigned long arg)
 442 {
 443         switch (cmd) {
 444         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 445                 return pty_set_lock(tty, (int __user *)arg);
 446         case TIOCGPTN: /* Get PT Number */
 447                 return put_user(tty->index, (unsigned int __user *)arg);
 448         case TIOCSIG:    /* Send signal to other side of pty */
 449                 return pty_signal(tty, (int) arg);
 450         }
 451
 452         return -ENOIOCTLCMD;
 453 }
 454
 455 /**
 456  *      ptm_unix98_lookup       -       find a pty master
 457  *      @driver: ptm driver
 458  *      @idx: tty index
 459  *
 460  *      Look up a pty master device. Called under the tty_mutex for now.
 461  *      This provides our locking.
 462  */
 463
 464 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 465                 struct inode *ptm_inode, int idx)
 466 {
 467         /* Master must be open via /dev/ptmx */
 468         return ERR_PTR(-EIO);
 469 }
 470
 471 /**
 472  *      pts_unix98_lookup       -       find a pty slave
 473  *      @driver: pts driver
 474  *      @idx: tty index
 475  *
 476  *      Look up a pty master device. Called under the tty_mutex for now.
 477  *      This provides our locking.
 478  */
 479
 480 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 481                 struct inode *pts_inode, int idx)
 482 {
 483         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 484         /* Master must be open before slave */
 485         if (!tty)
 486                 return ERR_PTR(-EIO);
 487         return tty;
 488 }
 489
 490 static void pty_unix98_shutdown(struct tty_struct *tty)
 491 {
 492         tty_driver_remove_tty(tty->driver, tty);
 493         /* We have our own method as we don't use the tty index */
 494         kfree(tty->termios);
 495 }
 496
 497 /* We have no need to install and remove our tty objects as devpts does all
 498    the work for us */
 499
 500 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 501 {
 502         struct tty_struct *o_tty;
 503         int idx = tty->index;
 504
 505         o_tty = alloc_tty_struct();
 506         if (!o_tty)
 507                 return -ENOMEM;
 508         if (!try_module_get(driver->other->owner)) {
 509                 /* This cannot in fact currently happen */
 510                 goto err_free_tty;
 511         }
 512         initialize_tty_struct(o_tty, driver->other, idx);
 513
 514         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 515         if (tty->termios == NULL)
 516                 goto err_free_mem;
 517         *tty->termios = driver->init_termios;
 518         tty->termios_locked = tty->termios + 1;
 519
 520         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 521         if (o_tty->termios == NULL)
 522                 goto err_free_mem;
 523         *o_tty->termios = driver->other->init_termios;
 524         o_tty->termios_locked = o_tty->termios + 1;
 525
 526         tty_driver_kref_get(driver->other);
 527         if (driver->subtype == PTY_TYPE_MASTER)
 528                 o_tty->count++;
 529         /* Establish the links in both directions */
 530         tty->link   = o_tty;
 531         o_tty->link = tty;
 532         /*
 533          * All structures have been allocated, so now we install them.
 534          * Failures after this point use release_tty to clean up, so
 535          * there's no need to null out the local pointers.
 536          */
 537         tty_driver_kref_get(driver);
 538         tty->count++;
 539         return 0;
 540 err_free_mem:
 541         deinitialize_tty_struct(o_tty);
 542         kfree(o_tty->termios);
 543         kfree(tty->termios);
 544         module_put(o_tty->driver->owner);
 545 err_free_tty:
 546         free_tty_struct(o_tty);
 547         return -ENOMEM;
 548 }
 549
 550 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 551 {
 552 }
 553
 554 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 555 {
 556 }
 557
 558 static const struct tty_operations ptm_unix98_ops = {
 559         .lookup = ptm_unix98_lookup,
 560         .install = pty_unix98_install,
 561         .remove = ptm_unix98_remove,
 562         .open = pty_open,
 563         .close = pty_close,
 564         .write = pty_write,
 565         .write_room = pty_write_room,
 566         .flush_buffer = pty_flush_buffer,
 567         .chars_in_buffer = pty_chars_in_buffer,
 568         .unthrottle = pty_unthrottle,
 569         .set_termios = pty_set_termios,
 570         .ioctl = pty_unix98_ioctl,
 571         .shutdown = pty_unix98_shutdown,
 572         .resize = pty_resize
 573 };
 574
 575 static const struct tty_operations pty_unix98_ops = {
 576         .lookup = pts_unix98_lookup,
 577         .install = pty_unix98_install,
 578         .remove = pts_unix98_remove,
 579         .open = pty_open,
 580         .close = pty_close,
 581         .write = pty_write,
 582         .write_room = pty_write_room,
 583         .flush_buffer = pty_flush_buffer,
 584         .chars_in_buffer = pty_chars_in_buffer,
 585         .unthrottle = pty_unthrottle,
 586         .set_termios = pty_set_termios,
 587         .shutdown = pty_unix98_shutdown
 588 };
 589
 590 /**
 591  *      ptmx_open               -       open a unix 98 pty master
 592  *      @inode: inode of device file
 593  *      @filp: file pointer to tty
 594  *
 595  *      Allocate a unix98 pty master device from the ptmx driver.
 596  *
 597  *      Locking: tty_mutex protects the init_dev work. tty->count should
 598  *              protect the rest.
 599  *              allocated_ptys_lock handles the list of free pty numbers
 600  */
 601
 602 static int ptmx_open(struct inode *inode, struct file *filp)
 603 {
 604         struct tty_struct *tty;
 605         int retval;
 606         int index;
 607
 608         nonseekable_open(inode, filp);
 609
 610         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 611         filp->f_mode |= FMODE_NONOTIFY;
 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         tty_lock();
 628         tty = tty_init_dev(ptm_driver, index);
 629         mutex_unlock(&tty_mutex);
 630
 631         if (IS_ERR(tty)) {
 632                 retval = PTR_ERR(tty);
 633                 goto out;
 634         }
 635
 636         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 637
 638         tty_add_file(tty, filp);
 639
 640         retval = devpts_pty_new(inode, tty->link);
 641         if (retval)
 642                 goto err_release;
 643
 644         retval = ptm_driver->ops->open(tty, filp);
 645         if (retval)
 646                 goto err_release;
 647
 648         tty_unlock();
 649         return 0;
 650 err_release:
 651         tty_unlock();
 652         tty_release(inode, filp);
 653         return retval;
 654 out:
 655         devpts_kill_index(inode, index);
 656         tty_unlock();
 657 err_file:
 658         tty_free_file(filp);
 659         return retval;
 660 }
 661
 662 static struct file_operations ptmx_fops;
 663
 664 static void __init unix98_pty_init(void)
 665 {
 666         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 667         if (!ptm_driver)
 668                 panic("Couldn't allocate Unix98 ptm driver");
 669         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 670         if (!pts_driver)
 671                 panic("Couldn't allocate Unix98 pts driver");
 672
 673         ptm_driver->driver_name = "pty_master";
 674         ptm_driver->name = "ptm";
 675         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 676         ptm_driver->minor_start = 0;
 677         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 678         ptm_driver->subtype = PTY_TYPE_MASTER;
 679         ptm_driver->init_termios = tty_std_termios;
 680         ptm_driver->init_termios.c_iflag = 0;
 681         ptm_driver->init_termios.c_oflag = 0;
 682         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 683         ptm_driver->init_termios.c_lflag = 0;
 684         ptm_driver->init_termios.c_ispeed = 38400;
 685         ptm_driver->init_termios.c_ospeed = 38400;
 686         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 687                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 688         ptm_driver->other = pts_driver;
 689         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 690
 691         pts_driver->driver_name = "pty_slave";
 692         pts_driver->name = "pts";
 693         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 694         pts_driver->minor_start = 0;
 695         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 696         pts_driver->subtype = PTY_TYPE_SLAVE;
 697         pts_driver->init_termios = tty_std_termios;
 698         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 699         pts_driver->init_termios.c_ispeed = 38400;
 700         pts_driver->init_termios.c_ospeed = 38400;
 701         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 702                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 703         pts_driver->other = ptm_driver;
 704         tty_set_operations(pts_driver, &pty_unix98_ops);
 705
 706         if (tty_register_driver(ptm_driver))
 707                 panic("Couldn't register Unix98 ptm driver");
 708         if (tty_register_driver(pts_driver))
 709                 panic("Couldn't register Unix98 pts driver");
 710
 711         /* Now create the /dev/ptmx special device */
 712         tty_default_fops(&ptmx_fops);
 713         ptmx_fops.open = ptmx_open;
 714
 715         cdev_init(&ptmx_cdev, &ptmx_fops);
 716         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 717             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 718                 panic("Couldn't register /dev/ptmx driver\n");
 719         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 720 }
 721
 722 #else
 723 static inline void unix98_pty_init(void) { }
 724 #endif
 725
 726 static int __init pty_init(void)
 727 {
 728         legacy_pty_init();
 729         unix98_pty_init();
 730         return 0;
 731 }
 732 module_init(pty_init);