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/sched.h>
  22 #include <linux/string.h>
  23 #include <linux/major.h>
  24 #include <linux/mm.h>
  25 #include <linux/init.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/sysctl.h>
  28 #include <linux/device.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/bitops.h>
  31 #include <linux/devpts_fs.h>
  32 #include <linux/slab.h>
  33
  34 #include <asm/system.h>
  35
  36 #ifdef CONFIG_UNIX98_PTYS
  37 static struct tty_driver *ptm_driver;
  38 static struct tty_driver *pts_driver;
  39 #endif
  40
  41 static void pty_close(struct tty_struct *tty, struct file *filp)
  42 {
  43         BUG_ON(!tty);
  44         if (tty->driver->subtype == PTY_TYPE_MASTER)
  45                 WARN_ON(tty->count > 1);
  46         else {
  47                 if (tty->count > 2)
  48                         return;
  49         }
  50         wake_up_interruptible(&tty->read_wait);
  51         wake_up_interruptible(&tty->write_wait);
  52         tty->packet = 0;
  53         if (!tty->link)
  54                 return;
  55         tty->link->packet = 0;
  56         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  57         wake_up_interruptible(&tty->link->read_wait);
  58         wake_up_interruptible(&tty->link->write_wait);
  59         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  60                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  61 #ifdef CONFIG_UNIX98_PTYS
  62                 if (tty->driver == ptm_driver)
  63                         devpts_pty_kill(tty->link);
  64 #endif
  65                 tty_unlock();
  66                 tty_vhangup(tty->link);
  67                 tty_lock();
  68         }
  69 }
  70
  71 /*
  72  * The unthrottle routine is called by the line discipline to signal
  73  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  74  * flag is always set, to force the line discipline to always call the
  75  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  76  * characters in the queue.  This is necessary since each time this
  77  * happens, we need to wake up any sleeping processes that could be
  78  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  79  * for the pty buffer to be drained.
  80  */
  81 static void pty_unthrottle(struct tty_struct *tty)
  82 {
  83         tty_wakeup(tty->link);
  84         set_bit(TTY_THROTTLED, &tty->flags);
  85 }
  86
  87 /**
  88  *      pty_space       -       report space left for writing
  89  *      @to: tty we are writing into
  90  *
  91  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  92  *      allows a lot of overspill room for echo and other fun messes to
  93  *      be handled properly
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = 8192 - to->buf.memory_used;
  99         if (n < 0)
 100                 return 0;
 101         return n;
 102 }
 103
 104 /**
 105  *      pty_write               -       write to a pty
 106  *      @tty: the tty we write from
 107  *      @buf: kernel buffer of data
 108  *      @count: bytes to write
 109  *
 110  *      Our "hardware" write method. Data is coming from the ldisc which
 111  *      may be in a non sleeping state. We simply throw this at the other
 112  *      end of the link as if we were an IRQ handler receiving stuff for
 113  *      the other side of the pty/tty pair.
 114  */
 115
 116 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 117 {
 118         struct tty_struct *to = tty->link;
 119
 120         if (tty->stopped)
 121                 return 0;
 122
 123         if (c > 0) {
 124                 /* Stuff the data into the input queue of the other end */
 125                 c = tty_insert_flip_string(to, buf, c);
 126                 /* And shovel */
 127                 if (c) {
 128                         tty_flip_buffer_push(to);
 129                         tty_wakeup(tty);
 130                 }
 131         }
 132         return c;
 133 }
 134
 135 /**
 136  *      pty_write_room  -       write space
 137  *      @tty: tty we are writing from
 138  *
 139  *      Report how many bytes the ldisc can send into the queue for
 140  *      the other device.
 141  */
 142
 143 static int pty_write_room(struct tty_struct *tty)
 144 {
 145         if (tty->stopped)
 146                 return 0;
 147         return pty_space(tty->link);
 148 }
 149
 150 /**
 151  *      pty_chars_in_buffer     -       characters currently in our tx queue
 152  *      @tty: our tty
 153  *
 154  *      Report how much we have in the transmit queue. As everything is
 155  *      instantly at the other end this is easy to implement.
 156  */
 157
 158 static int pty_chars_in_buffer(struct tty_struct *tty)
 159 {
 160         return 0;
 161 }
 162
 163 /* Set the lock flag on a pty */
 164 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 165 {
 166         int val;
 167         if (get_user(val, arg))
 168                 return -EFAULT;
 169         if (val)
 170                 set_bit(TTY_PTY_LOCK, &tty->flags);
 171         else
 172                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 173         return 0;
 174 }
 175
 176 /* Send a signal to the slave */
 177 static int pty_signal(struct tty_struct *tty, int sig)
 178 {
 179         unsigned long flags;
 180         struct pid *pgrp;
 181
 182         if (tty->link) {
 183                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 184                 pgrp = get_pid(tty->link->pgrp);
 185                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 186
 187                 kill_pgrp(pgrp, sig, 1);
 188                 put_pid(pgrp);
 189         }
 190         return 0;
 191 }
 192
 193 static void pty_flush_buffer(struct tty_struct *tty)
 194 {
 195         struct tty_struct *to = tty->link;
 196         unsigned long flags;
 197
 198         if (!to)
 199                 return;
 200         /* tty_buffer_flush(to); FIXME */
 201         if (to->packet) {
 202                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 203                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 204                 wake_up_interruptible(&to->read_wait);
 205                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 206         }
 207 }
 208
 209 static int pty_open(struct tty_struct *tty, struct file *filp)
 210 {
 211         int     retval = -ENODEV;
 212
 213         if (!tty || !tty->link)
 214                 goto out;
 215
 216         retval = -EIO;
 217         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 218                 goto out;
 219         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 220                 goto out;
 221         if (tty->link->count != 1)
 222                 goto out;
 223
 224         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 225         set_bit(TTY_THROTTLED, &tty->flags);
 226         retval = 0;
 227 out:
 228         return retval;
 229 }
 230
 231 static void pty_set_termios(struct tty_struct *tty,
 232                                         struct ktermios *old_termios)
 233 {
 234         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 235         tty->termios->c_cflag |= (CS8 | CREAD);
 236 }
 237
 238 /**
 239  *      pty_do_resize           -       resize event
 240  *      @tty: tty being resized
 241  *      @ws: window size being set.
 242  *
 243  *      Update the termios variables and send the necessary signals to
 244  *      peform a terminal resize correctly
 245  */
 246
 247 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 248 {
 249         struct pid *pgrp, *rpgrp;
 250         unsigned long flags;
 251         struct tty_struct *pty = tty->link;
 252
 253         /* For a PTY we need to lock the tty side */
 254         mutex_lock(&tty->termios_mutex);
 255         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 256                 goto done;
 257
 258         /* Get the PID values and reference them so we can
 259            avoid holding the tty ctrl lock while sending signals.
 260            We need to lock these individually however. */
 261
 262         spin_lock_irqsave(&tty->ctrl_lock, flags);
 263         pgrp = get_pid(tty->pgrp);
 264         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 265
 266         spin_lock_irqsave(&pty->ctrl_lock, flags);
 267         rpgrp = get_pid(pty->pgrp);
 268         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 269
 270         if (pgrp)
 271                 kill_pgrp(pgrp, SIGWINCH, 1);
 272         if (rpgrp != pgrp && rpgrp)
 273                 kill_pgrp(rpgrp, SIGWINCH, 1);
 274
 275         put_pid(pgrp);
 276         put_pid(rpgrp);
 277
 278         tty->winsize = *ws;
 279         pty->winsize = *ws;     /* Never used so will go away soon */
 280 done:
 281         mutex_unlock(&tty->termios_mutex);
 282         return 0;
 283 }
 284
 285 /* Traditional BSD devices */
 286 #ifdef CONFIG_LEGACY_PTYS
 287
 288 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 289 {
 290         struct tty_struct *o_tty;
 291         int idx = tty->index;
 292         int retval;
 293
 294         o_tty = alloc_tty_struct();
 295         if (!o_tty)
 296                 return -ENOMEM;
 297         if (!try_module_get(driver->other->owner)) {
 298                 /* This cannot in fact currently happen */
 299                 free_tty_struct(o_tty);
 300                 return -ENOMEM;
 301         }
 302         initialize_tty_struct(o_tty, driver->other, idx);
 303
 304         /* We always use new tty termios data so we can do this
 305            the easy way .. */
 306         retval = tty_init_termios(tty);
 307         if (retval)
 308                 goto free_mem_out;
 309
 310         retval = tty_init_termios(o_tty);
 311         if (retval) {
 312                 tty_free_termios(tty);
 313                 goto free_mem_out;
 314         }
 315
 316         /*
 317          * Everything allocated ... set up the o_tty structure.
 318          */
 319         driver->other->ttys[idx] = o_tty;
 320         tty_driver_kref_get(driver->other);
 321         if (driver->subtype == PTY_TYPE_MASTER)
 322                 o_tty->count++;
 323         /* Establish the links in both directions */
 324         tty->link   = o_tty;
 325         o_tty->link = tty;
 326
 327         tty_driver_kref_get(driver);
 328         tty->count++;
 329         driver->ttys[idx] = tty;
 330         return 0;
 331 free_mem_out:
 332         module_put(o_tty->driver->owner);
 333         free_tty_struct(o_tty);
 334         return -ENOMEM;
 335 }
 336
 337 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 338                          unsigned int cmd, unsigned long arg)
 339 {
 340         switch (cmd) {
 341         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 342                 return pty_set_lock(tty, (int __user *) arg);
 343         case TIOCSIG:    /* Send signal to other side of pty */
 344                 return pty_signal(tty, (int) arg);
 345         }
 346         return -ENOIOCTLCMD;
 347 }
 348
 349 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 350 module_param(legacy_count, int, 0);
 351
 352 /*
 353  * The master side of a pty can do TIOCSPTLCK and thus
 354  * has pty_bsd_ioctl.
 355  */
 356 static const struct tty_operations master_pty_ops_bsd = {
 357         .install = pty_install,
 358         .open = pty_open,
 359         .close = pty_close,
 360         .write = pty_write,
 361         .write_room = pty_write_room,
 362         .flush_buffer = pty_flush_buffer,
 363         .chars_in_buffer = pty_chars_in_buffer,
 364         .unthrottle = pty_unthrottle,
 365         .set_termios = pty_set_termios,
 366         .ioctl = pty_bsd_ioctl,
 367         .resize = pty_resize
 368 };
 369
 370 static const struct tty_operations slave_pty_ops_bsd = {
 371         .install = pty_install,
 372         .open = pty_open,
 373         .close = pty_close,
 374         .write = pty_write,
 375         .write_room = pty_write_room,
 376         .flush_buffer = pty_flush_buffer,
 377         .chars_in_buffer = pty_chars_in_buffer,
 378         .unthrottle = pty_unthrottle,
 379         .set_termios = pty_set_termios,
 380         .resize = pty_resize
 381 };
 382
 383 static void __init legacy_pty_init(void)
 384 {
 385         struct tty_driver *pty_driver, *pty_slave_driver;
 386
 387         if (legacy_count <= 0)
 388                 return;
 389
 390         pty_driver = alloc_tty_driver(legacy_count);
 391         if (!pty_driver)
 392                 panic("Couldn't allocate pty driver");
 393
 394         pty_slave_driver = alloc_tty_driver(legacy_count);
 395         if (!pty_slave_driver)
 396                 panic("Couldn't allocate pty slave driver");
 397
 398         pty_driver->owner = THIS_MODULE;
 399         pty_driver->driver_name = "pty_master";
 400         pty_driver->name = "pty";
 401         pty_driver->major = PTY_MASTER_MAJOR;
 402         pty_driver->minor_start = 0;
 403         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 404         pty_driver->subtype = PTY_TYPE_MASTER;
 405         pty_driver->init_termios = tty_std_termios;
 406         pty_driver->init_termios.c_iflag = 0;
 407         pty_driver->init_termios.c_oflag = 0;
 408         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 409         pty_driver->init_termios.c_lflag = 0;
 410         pty_driver->init_termios.c_ispeed = 38400;
 411         pty_driver->init_termios.c_ospeed = 38400;
 412         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 413         pty_driver->other = pty_slave_driver;
 414         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 415
 416         pty_slave_driver->owner = THIS_MODULE;
 417         pty_slave_driver->driver_name = "pty_slave";
 418         pty_slave_driver->name = "ttyp";
 419         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 420         pty_slave_driver->minor_start = 0;
 421         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 422         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 423         pty_slave_driver->init_termios = tty_std_termios;
 424         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 425         pty_slave_driver->init_termios.c_ispeed = 38400;
 426         pty_slave_driver->init_termios.c_ospeed = 38400;
 427         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 428                                         TTY_DRIVER_REAL_RAW;
 429         pty_slave_driver->other = pty_driver;
 430         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 431
 432         if (tty_register_driver(pty_driver))
 433                 panic("Couldn't register pty driver");
 434         if (tty_register_driver(pty_slave_driver))
 435                 panic("Couldn't register pty slave driver");
 436 }
 437 #else
 438 static inline void legacy_pty_init(void) { }
 439 #endif
 440
 441 /* Unix98 devices */
 442 #ifdef CONFIG_UNIX98_PTYS
 443 /*
 444  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 445  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 446  */
 447 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 448 static int pty_limit_min;
 449 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 450 static int pty_count;
 451
 452 static struct cdev ptmx_cdev;
 453
 454 static struct ctl_table pty_table[] = {
 455         {
 456                 .procname       = "max",
 457                 .maxlen         = sizeof(int),
 458                 .mode           = 0644,
 459                 .data           = &pty_limit,
 460                 .proc_handler   = proc_dointvec_minmax,
 461                 .extra1         = &pty_limit_min,
 462                 .extra2         = &pty_limit_max,
 463         }, {
 464                 .procname       = "nr",
 465                 .maxlen         = sizeof(int),
 466                 .mode           = 0444,
 467                 .data           = &pty_count,
 468                 .proc_handler   = proc_dointvec,
 469         },
 470         {}
 471 };
 472
 473 static struct ctl_table pty_kern_table[] = {
 474         {
 475                 .procname       = "pty",
 476                 .mode           = 0555,
 477                 .child          = pty_table,
 478         },
 479         {}
 480 };
 481
 482 static struct ctl_table pty_root_table[] = {
 483         {
 484                 .procname       = "kernel",
 485                 .mode           = 0555,
 486                 .child          = pty_kern_table,
 487         },
 488         {}
 489 };
 490
 491
 492 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 493                             unsigned int cmd, unsigned long arg)
 494 {
 495         switch (cmd) {
 496         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 497                 return pty_set_lock(tty, (int __user *)arg);
 498         case TIOCGPTN: /* Get PT Number */
 499                 return put_user(tty->index, (unsigned int __user *)arg);
 500         case TIOCSIG:    /* Send signal to other side of pty */
 501                 return pty_signal(tty, (int) arg);
 502         }
 503
 504         return -ENOIOCTLCMD;
 505 }
 506
 507 /**
 508  *      ptm_unix98_lookup       -       find a pty master
 509  *      @driver: ptm driver
 510  *      @idx: tty index
 511  *
 512  *      Look up a pty master device. Called under the tty_mutex for now.
 513  *      This provides our locking.
 514  */
 515
 516 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 517                 struct inode *ptm_inode, int idx)
 518 {
 519         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 520         if (tty)
 521                 tty = tty->link;
 522         return tty;
 523 }
 524
 525 /**
 526  *      pts_unix98_lookup       -       find a pty slave
 527  *      @driver: pts driver
 528  *      @idx: tty index
 529  *
 530  *      Look up a pty master device. Called under the tty_mutex for now.
 531  *      This provides our locking.
 532  */
 533
 534 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 535                 struct inode *pts_inode, int idx)
 536 {
 537         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 538         /* Master must be open before slave */
 539         if (!tty)
 540                 return ERR_PTR(-EIO);
 541         return tty;
 542 }
 543
 544 static void pty_unix98_shutdown(struct tty_struct *tty)
 545 {
 546         /* We have our own method as we don't use the tty index */
 547         kfree(tty->termios);
 548 }
 549
 550 /* We have no need to install and remove our tty objects as devpts does all
 551    the work for us */
 552
 553 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 554 {
 555         struct tty_struct *o_tty;
 556         int idx = tty->index;
 557
 558         o_tty = alloc_tty_struct();
 559         if (!o_tty)
 560                 return -ENOMEM;
 561         if (!try_module_get(driver->other->owner)) {
 562                 /* This cannot in fact currently happen */
 563                 free_tty_struct(o_tty);
 564                 return -ENOMEM;
 565         }
 566         initialize_tty_struct(o_tty, driver->other, idx);
 567
 568         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 569         if (tty->termios == NULL)
 570                 goto free_mem_out;
 571         *tty->termios = driver->init_termios;
 572         tty->termios_locked = tty->termios + 1;
 573
 574         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 575         if (o_tty->termios == NULL)
 576                 goto free_mem_out;
 577         *o_tty->termios = driver->other->init_termios;
 578         o_tty->termios_locked = o_tty->termios + 1;
 579
 580         tty_driver_kref_get(driver->other);
 581         if (driver->subtype == PTY_TYPE_MASTER)
 582                 o_tty->count++;
 583         /* Establish the links in both directions */
 584         tty->link   = o_tty;
 585         o_tty->link = tty;
 586         /*
 587          * All structures have been allocated, so now we install them.
 588          * Failures after this point use release_tty to clean up, so
 589          * there's no need to null out the local pointers.
 590          */
 591         tty_driver_kref_get(driver);
 592         tty->count++;
 593         pty_count++;
 594         return 0;
 595 free_mem_out:
 596         kfree(o_tty->termios);
 597         module_put(o_tty->driver->owner);
 598         free_tty_struct(o_tty);
 599         kfree(tty->termios);
 600         return -ENOMEM;
 601 }
 602
 603 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 604 {
 605         pty_count--;
 606 }
 607
 608 static const struct tty_operations ptm_unix98_ops = {
 609         .lookup = ptm_unix98_lookup,
 610         .install = pty_unix98_install,
 611         .remove = pty_unix98_remove,
 612         .open = pty_open,
 613         .close = pty_close,
 614         .write = pty_write,
 615         .write_room = pty_write_room,
 616         .flush_buffer = pty_flush_buffer,
 617         .chars_in_buffer = pty_chars_in_buffer,
 618         .unthrottle = pty_unthrottle,
 619         .set_termios = pty_set_termios,
 620         .ioctl = pty_unix98_ioctl,
 621         .shutdown = pty_unix98_shutdown,
 622         .resize = pty_resize
 623 };
 624
 625 static const struct tty_operations pty_unix98_ops = {
 626         .lookup = pts_unix98_lookup,
 627         .install = pty_unix98_install,
 628         .remove = pty_unix98_remove,
 629         .open = pty_open,
 630         .close = pty_close,
 631         .write = pty_write,
 632         .write_room = pty_write_room,
 633         .flush_buffer = pty_flush_buffer,
 634         .chars_in_buffer = pty_chars_in_buffer,
 635         .unthrottle = pty_unthrottle,
 636         .set_termios = pty_set_termios,
 637         .shutdown = pty_unix98_shutdown
 638 };
 639
 640 /**
 641  *      ptmx_open               -       open a unix 98 pty master
 642  *      @inode: inode of device file
 643  *      @filp: file pointer to tty
 644  *
 645  *      Allocate a unix98 pty master device from the ptmx driver.
 646  *
 647  *      Locking: tty_mutex protects the init_dev work. tty->count should
 648  *              protect the rest.
 649  *              allocated_ptys_lock handles the list of free pty numbers
 650  */
 651
 652 static int ptmx_open(struct inode *inode, struct file *filp)
 653 {
 654         struct tty_struct *tty;
 655         int retval;
 656         int index;
 657
 658         nonseekable_open(inode, filp);
 659
 660         /* find a device that is not in use. */
 661         tty_lock();
 662         index = devpts_new_index(inode);
 663         tty_unlock();
 664         if (index < 0)
 665                 return index;
 666
 667         mutex_lock(&tty_mutex);
 668         tty_lock();
 669         tty = tty_init_dev(ptm_driver, index, 1);
 670         mutex_unlock(&tty_mutex);
 671
 672         if (IS_ERR(tty)) {
 673                 retval = PTR_ERR(tty);
 674                 goto out;
 675         }
 676
 677         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 678
 679         tty_add_file(tty, filp);
 680
 681         retval = devpts_pty_new(inode, tty->link);
 682         if (retval)
 683                 goto out1;
 684
 685         retval = ptm_driver->ops->open(tty, filp);
 686         if (retval)
 687                 goto out2;
 688 out1:
 689         tty_unlock();
 690         return retval;
 691 out2:
 692         tty_unlock();
 693         tty_release(inode, filp);
 694         return retval;
 695 out:
 696         devpts_kill_index(inode, index);
 697         tty_unlock();
 698         return retval;
 699 }
 700
 701 static struct file_operations ptmx_fops;
 702
 703 static void __init unix98_pty_init(void)
 704 {
 705         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 706         if (!ptm_driver)
 707                 panic("Couldn't allocate Unix98 ptm driver");
 708         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 709         if (!pts_driver)
 710                 panic("Couldn't allocate Unix98 pts driver");
 711
 712         ptm_driver->owner = THIS_MODULE;
 713         ptm_driver->driver_name = "pty_master";
 714         ptm_driver->name = "ptm";
 715         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 716         ptm_driver->minor_start = 0;
 717         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 718         ptm_driver->subtype = PTY_TYPE_MASTER;
 719         ptm_driver->init_termios = tty_std_termios;
 720         ptm_driver->init_termios.c_iflag = 0;
 721         ptm_driver->init_termios.c_oflag = 0;
 722         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 723         ptm_driver->init_termios.c_lflag = 0;
 724         ptm_driver->init_termios.c_ispeed = 38400;
 725         ptm_driver->init_termios.c_ospeed = 38400;
 726         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 727                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 728         ptm_driver->other = pts_driver;
 729         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 730
 731         pts_driver->owner = THIS_MODULE;
 732         pts_driver->driver_name = "pty_slave";
 733         pts_driver->name = "pts";
 734         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 735         pts_driver->minor_start = 0;
 736         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 737         pts_driver->subtype = PTY_TYPE_SLAVE;
 738         pts_driver->init_termios = tty_std_termios;
 739         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 740         pts_driver->init_termios.c_ispeed = 38400;
 741         pts_driver->init_termios.c_ospeed = 38400;
 742         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 743                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 744         pts_driver->other = ptm_driver;
 745         tty_set_operations(pts_driver, &pty_unix98_ops);
 746
 747         if (tty_register_driver(ptm_driver))
 748                 panic("Couldn't register Unix98 ptm driver");
 749         if (tty_register_driver(pts_driver))
 750                 panic("Couldn't register Unix98 pts driver");
 751
 752         register_sysctl_table(pty_root_table);
 753
 754         /* Now create the /dev/ptmx special device */
 755         tty_default_fops(&ptmx_fops);
 756         ptmx_fops.open = ptmx_open;
 757
 758         cdev_init(&ptmx_cdev, &ptmx_fops);
 759         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 760             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 761                 panic("Couldn't register /dev/ptmx driver\n");
 762         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 763 }
 764
 765 #else
 766 static inline void unix98_pty_init(void) { }
 767 #endif
 768
 769 static int __init pty_init(void)
 770 {
 771         legacy_pty_init();
 772         unix98_pty_init();
 773         return 0;
 774 }
 775 module_init(pty_init);