drivers/char/pty.c

   1 /*
   2  *  linux/drivers/char/pty.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added support for a Unix98-style ptmx device.
   7  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   8  *
   9  *  When reading this code see also fs/devpts. In particular note that the
  10  *  driver_data field is used by the devpts side as a binding to the devpts
  11  *  inode.
  12  */
  13
  14 #include <linux/module.h>
  15
  16 #include <linux/errno.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_flip.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/string.h>
  22 #include <linux/major.h>
  23 #include <linux/mm.h>
  24 #include <linux/init.h>
  25 #include <linux/sysctl.h>
  26 #include <linux/device.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/bitops.h>
  29 #include <linux/devpts_fs.h>
  30
  31 #include <asm/system.h>
  32
  33 #ifdef CONFIG_UNIX98_PTYS
  34 static struct tty_driver *ptm_driver;
  35 static struct tty_driver *pts_driver;
  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                         devpts_pty_kill(tty->link);
  61 #endif
  62                 tty_vhangup(tty->link);
  63         }
  64 }
  65
  66 /*
  67  * The unthrottle routine is called by the line discipline to signal
  68  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  69  * flag is always set, to force the line discipline to always call the
  70  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  71  * characters in the queue.  This is necessary since each time this
  72  * happens, we need to wake up any sleeping processes that could be
  73  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  74  * for the pty buffer to be drained.
  75  */
  76 static void pty_unthrottle(struct tty_struct *tty)
  77 {
  78         tty_wakeup(tty->link);
  79         set_bit(TTY_THROTTLED, &tty->flags);
  80 }
  81
  82 /**
  83  *      pty_space       -       report space left for writing
  84  *      @to: tty we are writing into
  85  *
  86  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  87  *      allows a lot of overspill room for echo and other fun messes to
  88  *      be handled properly
  89  */
  90
  91 static int pty_space(struct tty_struct *to)
  92 {
  93         int n = 8192 - to->buf.memory_used;
  94         if (n < 0)
  95                 return 0;
  96         return n;
  97 }
  98
  99 /**
 100  *      pty_write               -       write to a pty
 101  *      @tty: the tty we write from
 102  *      @buf: kernel buffer of data
 103  *      @count: bytes to write
 104  *
 105  *      Our "hardware" write method. Data is coming from the ldisc which
 106  *      may be in a non sleeping state. We simply throw this at the other
 107  *      end of the link as if we were an IRQ handler receiving stuff for
 108  *      the other side of the pty/tty pair.
 109  */
 110
 111 static int pty_write(struct tty_struct *tty, const unsigned char *buf,
 112                                                                 int count)
 113 {
 114         struct tty_struct *to = tty->link;
 115         int c;
 116
 117         if (tty->stopped)
 118                 return 0;
 119
 120         /* This isn't locked but our 8K is quite sloppy so no
 121            big deal */
 122
 123         c = pty_space(to);
 124         if (c > count)
 125                 c = count;
 126         if (c > 0) {
 127                 /* Stuff the data into the input queue of the other end */
 128                 c = tty_insert_flip_string(to, buf, c);
 129                 /* And shovel */
 130                 tty_flip_buffer_push(to);
 131                 tty_wakeup(tty);
 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         return pty_space(tty->link);
 147 }
 148
 149 /**
 150  *      pty_chars_in_buffer     -       characters currently in our tx queue
 151  *      @tty: our tty
 152  *
 153  *      Report how much we have in the transmit queue. As everything is
 154  *      instantly at the other end this is easy to implement.
 155  */
 156
 157 static int pty_chars_in_buffer(struct tty_struct *tty)
 158 {
 159         return 0;
 160 }
 161
 162 /* Set the lock flag on a pty */
 163 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 164 {
 165         int val;
 166         if (get_user(val, arg))
 167                 return -EFAULT;
 168         if (val)
 169                 set_bit(TTY_PTY_LOCK, &tty->flags);
 170         else
 171                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 172         return 0;
 173 }
 174
 175 static void pty_flush_buffer(struct tty_struct *tty)
 176 {
 177         struct tty_struct *to = tty->link;
 178         unsigned long flags;
 179
 180         if (!to)
 181                 return;
 182         /* tty_buffer_flush(to); FIXME */
 183         if (to->packet) {
 184                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 185                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 186                 wake_up_interruptible(&to->read_wait);
 187                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 188         }
 189 }
 190
 191 static int pty_open(struct tty_struct *tty, struct file *filp)
 192 {
 193         int     retval = -ENODEV;
 194
 195         if (!tty || !tty->link)
 196                 goto out;
 197
 198         retval = -EIO;
 199         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 200                 goto out;
 201         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 202                 goto out;
 203         if (tty->link->count != 1)
 204                 goto out;
 205
 206         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 207         set_bit(TTY_THROTTLED, &tty->flags);
 208         retval = 0;
 209 out:
 210         return retval;
 211 }
 212
 213 static void pty_set_termios(struct tty_struct *tty,
 214                                         struct ktermios *old_termios)
 215 {
 216         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 217         tty->termios->c_cflag |= (CS8 | CREAD);
 218 }
 219
 220 /**
 221  *      pty_do_resize           -       resize event
 222  *      @tty: tty being resized
 223  *      @ws: window size being set.
 224  *
 225  *      Update the termios variables and send the neccessary signals to
 226  *      peform a terminal resize correctly
 227  */
 228
 229 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 230 {
 231         struct pid *pgrp, *rpgrp;
 232         unsigned long flags;
 233         struct tty_struct *pty = tty->link;
 234
 235         /* For a PTY we need to lock the tty side */
 236         mutex_lock(&tty->termios_mutex);
 237         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 238                 goto done;
 239
 240         /* Get the PID values and reference them so we can
 241            avoid holding the tty ctrl lock while sending signals.
 242            We need to lock these individually however. */
 243
 244         spin_lock_irqsave(&tty->ctrl_lock, flags);
 245         pgrp = get_pid(tty->pgrp);
 246         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 247
 248         spin_lock_irqsave(&pty->ctrl_lock, flags);
 249         rpgrp = get_pid(pty->pgrp);
 250         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 251
 252         if (pgrp)
 253                 kill_pgrp(pgrp, SIGWINCH, 1);
 254         if (rpgrp != pgrp && rpgrp)
 255                 kill_pgrp(rpgrp, SIGWINCH, 1);
 256
 257         put_pid(pgrp);
 258         put_pid(rpgrp);
 259
 260         tty->winsize = *ws;
 261         pty->winsize = *ws;     /* Never used so will go away soon */
 262 done:
 263         mutex_unlock(&tty->termios_mutex);
 264         return 0;
 265 }
 266
 267 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 268 {
 269         struct tty_struct *o_tty;
 270         int idx = tty->index;
 271         int retval;
 272
 273         o_tty = alloc_tty_struct();
 274         if (!o_tty)
 275                 return -ENOMEM;
 276         if (!try_module_get(driver->other->owner)) {
 277                 /* This cannot in fact currently happen */
 278                 free_tty_struct(o_tty);
 279                 return -ENOMEM;
 280         }
 281         initialize_tty_struct(o_tty, driver->other, idx);
 282
 283         /* We always use new tty termios data so we can do this
 284            the easy way .. */
 285         retval = tty_init_termios(tty);
 286         if (retval)
 287                 goto free_mem_out;
 288
 289         retval = tty_init_termios(o_tty);
 290         if (retval) {
 291                 tty_free_termios(tty);
 292                 goto free_mem_out;
 293         }
 294
 295         /*
 296          * Everything allocated ... set up the o_tty structure.
 297          */
 298         driver->other->ttys[idx] = o_tty;
 299         tty_driver_kref_get(driver->other);
 300         if (driver->subtype == PTY_TYPE_MASTER)
 301                 o_tty->count++;
 302         /* Establish the links in both directions */
 303         tty->link   = o_tty;
 304         o_tty->link = tty;
 305
 306         tty_driver_kref_get(driver);
 307         tty->count++;
 308         driver->ttys[idx] = tty;
 309         return 0;
 310 free_mem_out:
 311         module_put(o_tty->driver->owner);
 312         free_tty_struct(o_tty);
 313         return -ENOMEM;
 314 }
 315
 316
 317 static const struct tty_operations pty_ops = {
 318         .install = pty_install,
 319         .open = pty_open,
 320         .close = pty_close,
 321         .write = pty_write,
 322         .write_room = pty_write_room,
 323         .flush_buffer = pty_flush_buffer,
 324         .chars_in_buffer = pty_chars_in_buffer,
 325         .unthrottle = pty_unthrottle,
 326         .set_termios = pty_set_termios,
 327         .resize = pty_resize
 328 };
 329
 330 /* Traditional BSD devices */
 331 #ifdef CONFIG_LEGACY_PTYS
 332 static struct tty_driver *pty_driver, *pty_slave_driver;
 333
 334 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 335                          unsigned int cmd, unsigned long arg)
 336 {
 337         switch (cmd) {
 338         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 339                 return pty_set_lock(tty, (int __user *) arg);
 340         }
 341         return -ENOIOCTLCMD;
 342 }
 343
 344 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 345 module_param(legacy_count, int, 0);
 346
 347 static const struct tty_operations pty_ops_bsd = {
 348         .open = pty_open,
 349         .close = pty_close,
 350         .write = pty_write,
 351         .write_room = pty_write_room,
 352         .flush_buffer = pty_flush_buffer,
 353         .chars_in_buffer = pty_chars_in_buffer,
 354         .unthrottle = pty_unthrottle,
 355         .set_termios = pty_set_termios,
 356         .ioctl = pty_bsd_ioctl,
 357         .resize = pty_resize
 358 };
 359
 360 static void __init legacy_pty_init(void)
 361 {
 362         if (legacy_count <= 0)
 363                 return;
 364
 365         pty_driver = alloc_tty_driver(legacy_count);
 366         if (!pty_driver)
 367                 panic("Couldn't allocate pty driver");
 368
 369         pty_slave_driver = alloc_tty_driver(legacy_count);
 370         if (!pty_slave_driver)
 371                 panic("Couldn't allocate pty slave driver");
 372
 373         pty_driver->owner = THIS_MODULE;
 374         pty_driver->driver_name = "pty_master";
 375         pty_driver->name = "pty";
 376         pty_driver->major = PTY_MASTER_MAJOR;
 377         pty_driver->minor_start = 0;
 378         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 379         pty_driver->subtype = PTY_TYPE_MASTER;
 380         pty_driver->init_termios = tty_std_termios;
 381         pty_driver->init_termios.c_iflag = 0;
 382         pty_driver->init_termios.c_oflag = 0;
 383         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 384         pty_driver->init_termios.c_lflag = 0;
 385         pty_driver->init_termios.c_ispeed = 38400;
 386         pty_driver->init_termios.c_ospeed = 38400;
 387         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 388         pty_driver->other = pty_slave_driver;
 389         tty_set_operations(pty_driver, &pty_ops);
 390
 391         pty_slave_driver->owner = THIS_MODULE;
 392         pty_slave_driver->driver_name = "pty_slave";
 393         pty_slave_driver->name = "ttyp";
 394         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 395         pty_slave_driver->minor_start = 0;
 396         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 397         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 398         pty_slave_driver->init_termios = tty_std_termios;
 399         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 400         pty_slave_driver->init_termios.c_ispeed = 38400;
 401         pty_slave_driver->init_termios.c_ospeed = 38400;
 402         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 403                                         TTY_DRIVER_REAL_RAW;
 404         pty_slave_driver->other = pty_driver;
 405         tty_set_operations(pty_slave_driver, &pty_ops);
 406
 407         if (tty_register_driver(pty_driver))
 408                 panic("Couldn't register pty driver");
 409         if (tty_register_driver(pty_slave_driver))
 410                 panic("Couldn't register pty slave driver");
 411 }
 412 #else
 413 static inline void legacy_pty_init(void) { }
 414 #endif
 415
 416 /* Unix98 devices */
 417 #ifdef CONFIG_UNIX98_PTYS
 418 /*
 419  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 420  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 421  */
 422 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 423 static int pty_limit_min;
 424 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 425 static int pty_count;
 426
 427 static struct cdev ptmx_cdev;
 428
 429 static struct ctl_table pty_table[] = {
 430         {
 431                 .ctl_name       = PTY_MAX,
 432                 .procname       = "max",
 433                 .maxlen         = sizeof(int),
 434                 .mode           = 0644,
 435                 .data           = &pty_limit,
 436                 .proc_handler   = &proc_dointvec_minmax,
 437                 .strategy       = &sysctl_intvec,
 438                 .extra1         = &pty_limit_min,
 439                 .extra2         = &pty_limit_max,
 440         }, {
 441                 .ctl_name       = PTY_NR,
 442                 .procname       = "nr",
 443                 .maxlen         = sizeof(int),
 444                 .mode           = 0444,
 445                 .data           = &pty_count,
 446                 .proc_handler   = &proc_dointvec,
 447         }, {
 448                 .ctl_name       = 0
 449         }
 450 };
 451
 452 static struct ctl_table pty_kern_table[] = {
 453         {
 454                 .ctl_name       = KERN_PTY,
 455                 .procname       = "pty",
 456                 .mode           = 0555,
 457                 .child          = pty_table,
 458         },
 459         {}
 460 };
 461
 462 static struct ctl_table pty_root_table[] = {
 463         {
 464                 .ctl_name       = CTL_KERN,
 465                 .procname       = "kernel",
 466                 .mode           = 0555,
 467                 .child          = pty_kern_table,
 468         },
 469         {}
 470 };
 471
 472
 473 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 474                             unsigned int cmd, unsigned long arg)
 475 {
 476         switch (cmd) {
 477         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 478                 return pty_set_lock(tty, (int __user *)arg);
 479         case TIOCGPTN: /* Get PT Number */
 480                 return put_user(tty->index, (unsigned int __user *)arg);
 481         }
 482
 483         return -ENOIOCTLCMD;
 484 }
 485
 486 /**
 487  *      ptm_unix98_lookup       -       find a pty master
 488  *      @driver: ptm driver
 489  *      @idx: tty index
 490  *
 491  *      Look up a pty master device. Called under the tty_mutex for now.
 492  *      This provides our locking.
 493  */
 494
 495 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 496                 struct inode *ptm_inode, int idx)
 497 {
 498         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 499         if (tty)
 500                 tty = tty->link;
 501         return tty;
 502 }
 503
 504 /**
 505  *      pts_unix98_lookup       -       find a pty slave
 506  *      @driver: pts driver
 507  *      @idx: tty index
 508  *
 509  *      Look up a pty master device. Called under the tty_mutex for now.
 510  *      This provides our locking.
 511  */
 512
 513 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 514                 struct inode *pts_inode, int idx)
 515 {
 516         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 517         /* Master must be open before slave */
 518         if (!tty)
 519                 return ERR_PTR(-EIO);
 520         return tty;
 521 }
 522
 523 static void pty_unix98_shutdown(struct tty_struct *tty)
 524 {
 525         /* We have our own method as we don't use the tty index */
 526         kfree(tty->termios);
 527 }
 528
 529 /* We have no need to install and remove our tty objects as devpts does all
 530    the work for us */
 531
 532 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 533 {
 534         struct tty_struct *o_tty;
 535         int idx = tty->index;
 536
 537         o_tty = alloc_tty_struct();
 538         if (!o_tty)
 539                 return -ENOMEM;
 540         if (!try_module_get(driver->other->owner)) {
 541                 /* This cannot in fact currently happen */
 542                 free_tty_struct(o_tty);
 543                 return -ENOMEM;
 544         }
 545         initialize_tty_struct(o_tty, driver->other, idx);
 546
 547         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 548         if (tty->termios == NULL)
 549                 goto free_mem_out;
 550         *tty->termios = driver->init_termios;
 551         tty->termios_locked = tty->termios + 1;
 552
 553         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 554         if (o_tty->termios == NULL)
 555                 goto free_mem_out;
 556         *o_tty->termios = driver->other->init_termios;
 557         o_tty->termios_locked = o_tty->termios + 1;
 558
 559         tty_driver_kref_get(driver->other);
 560         if (driver->subtype == PTY_TYPE_MASTER)
 561                 o_tty->count++;
 562         /* Establish the links in both directions */
 563         tty->link   = o_tty;
 564         o_tty->link = tty;
 565         /*
 566          * All structures have been allocated, so now we install them.
 567          * Failures after this point use release_tty to clean up, so
 568          * there's no need to null out the local pointers.
 569          */
 570         tty_driver_kref_get(driver);
 571         tty->count++;
 572         pty_count++;
 573         return 0;
 574 free_mem_out:
 575         kfree(o_tty->termios);
 576         module_put(o_tty->driver->owner);
 577         free_tty_struct(o_tty);
 578         kfree(tty->termios);
 579         return -ENOMEM;
 580 }
 581
 582 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 583 {
 584         pty_count--;
 585 }
 586
 587 static const struct tty_operations ptm_unix98_ops = {
 588         .lookup = ptm_unix98_lookup,
 589         .install = pty_unix98_install,
 590         .remove = pty_unix98_remove,
 591         .open = pty_open,
 592         .close = pty_close,
 593         .write = pty_write,
 594         .write_room = pty_write_room,
 595         .flush_buffer = pty_flush_buffer,
 596         .chars_in_buffer = pty_chars_in_buffer,
 597         .unthrottle = pty_unthrottle,
 598         .set_termios = pty_set_termios,
 599         .ioctl = pty_unix98_ioctl,
 600         .shutdown = pty_unix98_shutdown,
 601         .resize = pty_resize
 602 };
 603
 604 static const struct tty_operations pty_unix98_ops = {
 605         .lookup = pts_unix98_lookup,
 606         .install = pty_unix98_install,
 607         .remove = pty_unix98_remove,
 608         .open = pty_open,
 609         .close = pty_close,
 610         .write = pty_write,
 611         .write_room = pty_write_room,
 612         .flush_buffer = pty_flush_buffer,
 613         .chars_in_buffer = pty_chars_in_buffer,
 614         .unthrottle = pty_unthrottle,
 615         .set_termios = pty_set_termios,
 616         .shutdown = pty_unix98_shutdown
 617 };
 618
 619 /**
 620  *      ptmx_open               -       open a unix 98 pty master
 621  *      @inode: inode of device file
 622  *      @filp: file pointer to tty
 623  *
 624  *      Allocate a unix98 pty master device from the ptmx driver.
 625  *
 626  *      Locking: tty_mutex protects the init_dev work. tty->count should
 627  *              protect the rest.
 628  *              allocated_ptys_lock handles the list of free pty numbers
 629  */
 630
 631 static int __ptmx_open(struct inode *inode, struct file *filp)
 632 {
 633         struct tty_struct *tty;
 634         int retval;
 635         int index;
 636
 637         nonseekable_open(inode, filp);
 638
 639         /* find a device that is not in use. */
 640         index = devpts_new_index(inode);
 641         if (index < 0)
 642                 return index;
 643
 644         mutex_lock(&tty_mutex);
 645         tty = tty_init_dev(ptm_driver, index, 1);
 646         mutex_unlock(&tty_mutex);
 647
 648         if (IS_ERR(tty)) {
 649                 retval = PTR_ERR(tty);
 650                 goto out;
 651         }
 652
 653         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 654         filp->private_data = tty;
 655         file_move(filp, &tty->tty_files);
 656
 657         retval = devpts_pty_new(inode, tty->link);
 658         if (retval)
 659                 goto out1;
 660
 661         retval = ptm_driver->ops->open(tty, filp);
 662         if (!retval)
 663                 return 0;
 664 out1:
 665         tty_release_dev(filp);
 666         return retval;
 667 out:
 668         devpts_kill_index(inode, index);
 669         return retval;
 670 }
 671
 672 static int ptmx_open(struct inode *inode, struct file *filp)
 673 {
 674         int ret;
 675
 676         lock_kernel();
 677         ret = __ptmx_open(inode, filp);
 678         unlock_kernel();
 679         return ret;
 680 }
 681
 682 static struct file_operations ptmx_fops;
 683
 684 static void __init unix98_pty_init(void)
 685 {
 686         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 687         if (!ptm_driver)
 688                 panic("Couldn't allocate Unix98 ptm driver");
 689         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 690         if (!pts_driver)
 691                 panic("Couldn't allocate Unix98 pts driver");
 692
 693         ptm_driver->owner = THIS_MODULE;
 694         ptm_driver->driver_name = "pty_master";
 695         ptm_driver->name = "ptm";
 696         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 697         ptm_driver->minor_start = 0;
 698         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 699         ptm_driver->subtype = PTY_TYPE_MASTER;
 700         ptm_driver->init_termios = tty_std_termios;
 701         ptm_driver->init_termios.c_iflag = 0;
 702         ptm_driver->init_termios.c_oflag = 0;
 703         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 704         ptm_driver->init_termios.c_lflag = 0;
 705         ptm_driver->init_termios.c_ispeed = 38400;
 706         ptm_driver->init_termios.c_ospeed = 38400;
 707         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 708                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 709         ptm_driver->other = pts_driver;
 710         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 711
 712         pts_driver->owner = THIS_MODULE;
 713         pts_driver->driver_name = "pty_slave";
 714         pts_driver->name = "pts";
 715         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 716         pts_driver->minor_start = 0;
 717         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 718         pts_driver->subtype = PTY_TYPE_SLAVE;
 719         pts_driver->init_termios = tty_std_termios;
 720         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 721         pts_driver->init_termios.c_ispeed = 38400;
 722         pts_driver->init_termios.c_ospeed = 38400;
 723         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 724                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 725         pts_driver->other = ptm_driver;
 726         tty_set_operations(pts_driver, &pty_unix98_ops);
 727
 728         if (tty_register_driver(ptm_driver))
 729                 panic("Couldn't register Unix98 ptm driver");
 730         if (tty_register_driver(pts_driver))
 731                 panic("Couldn't register Unix98 pts driver");
 732
 733         register_sysctl_table(pty_root_table);
 734
 735         /* Now create the /dev/ptmx special device */
 736         tty_default_fops(&ptmx_fops);
 737         ptmx_fops.open = ptmx_open;
 738
 739         cdev_init(&ptmx_cdev, &ptmx_fops);
 740         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 741             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 742                 panic("Couldn't register /dev/ptmx driver\n");
 743         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 744 }
 745
 746 #else
 747 static inline void unix98_pty_init(void) { }
 748 #endif
 749
 750 static int __init pty_init(void)
 751 {
 752         legacy_pty_init();
 753         unix98_pty_init();
 754         return 0;
 755 }
 756 module_init(pty_init);