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