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  */
   8
   9 #include <linux/module.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/tty.h>
  14 #include <linux/tty_flip.h>
  15 #include <linux/fcntl.h>
  16 #include <linux/sched.h>
  17 #include <linux/string.h>
  18 #include <linux/major.h>
  19 #include <linux/mm.h>
  20 #include <linux/init.h>
  21 #include <linux/device.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/bitops.h>
  24 #include <linux/devpts_fs.h>
  25 #include <linux/slab.h>
  26 #include <linux/mutex.h>
  27 #include <linux/poll.h>
  28
  29
  30 #ifdef CONFIG_UNIX98_PTYS
  31 static struct tty_driver *ptm_driver;
  32 static struct tty_driver *pts_driver;
  33 static DEFINE_MUTEX(devpts_mutex);
  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 (test_bit(TTY_IO_ERROR, &tty->flags))
  43                         return;
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         set_bit(TTY_IO_ERROR, &tty->flags);
  48         wake_up_interruptible(&tty->read_wait);
  49         wake_up_interruptible(&tty->write_wait);
  50         tty->packet = 0;
  51         /* Review - krefs on tty_link ?? */
  52         if (!tty->link)
  53                 return;
  54         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  55         wake_up_interruptible(&tty->link->read_wait);
  56         wake_up_interruptible(&tty->link->write_wait);
  57         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  58                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  59 #ifdef CONFIG_UNIX98_PTYS
  60                 if (tty->driver == ptm_driver) {
  61                         mutex_lock(&devpts_mutex);
  62                         if (tty->link->driver_data)
  63                                 devpts_pty_kill(tty->link->driver_data);
  64                         mutex_unlock(&devpts_mutex);
  65                 }
  66 #endif
  67                 tty_unlock(tty);
  68                 tty_vhangup(tty->link);
  69                 tty_lock(tty);
  70         }
  71 }
  72
  73 /*
  74  * The unthrottle routine is called by the line discipline to signal
  75  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  76  * flag is always set, to force the line discipline to always call the
  77  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  78  * characters in the queue.  This is necessary since each time this
  79  * happens, we need to wake up any sleeping processes that could be
  80  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  81  * for the pty buffer to be drained.
  82  */
  83 static void pty_unthrottle(struct tty_struct *tty)
  84 {
  85         tty_wakeup(tty->link);
  86         set_bit(TTY_THROTTLED, &tty->flags);
  87 }
  88
  89 /**
  90  *      pty_space       -       report space left for writing
  91  *      @to: tty we are writing into
  92  *
  93  *      Limit the buffer space used by ptys to 8k.
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = tty_buffer_space_avail(to->port);
  99         return min(n, 8192);
 100 }
 101
 102 /**
 103  *      pty_write               -       write to a pty
 104  *      @tty: the tty we write from
 105  *      @buf: kernel buffer of data
 106  *      @count: bytes to write
 107  *
 108  *      Our "hardware" write method. Data is coming from the ldisc which
 109  *      may be in a non sleeping state. We simply throw this at the other
 110  *      end of the link as if we were an IRQ handler receiving stuff for
 111  *      the other side of the pty/tty pair.
 112  */
 113
 114 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 115 {
 116         struct tty_struct *to = tty->link;
 117
 118         if (tty->stopped)
 119                 return 0;
 120
 121         if (c > 0) {
 122                 /* Stuff the data into the input queue of the other end */
 123                 c = tty_insert_flip_string(to->port, buf, c);
 124                 /* And shovel */
 125                 if (c)
 126                         tty_flip_buffer_push(to->port);
 127         }
 128         return c;
 129 }
 130
 131 /**
 132  *      pty_write_room  -       write space
 133  *      @tty: tty we are writing from
 134  *
 135  *      Report how many bytes the ldisc can send into the queue for
 136  *      the other device.
 137  */
 138
 139 static int pty_write_room(struct tty_struct *tty)
 140 {
 141         if (tty->stopped)
 142                 return 0;
 143         return pty_space(tty->link);
 144 }
 145
 146 /**
 147  *      pty_chars_in_buffer     -       characters currently in our tx queue
 148  *      @tty: our tty
 149  *
 150  *      Report how much we have in the transmit queue. As everything is
 151  *      instantly at the other end this is easy to implement.
 152  */
 153
 154 static int pty_chars_in_buffer(struct tty_struct *tty)
 155 {
 156         return 0;
 157 }
 158
 159 /* Set the lock flag on a pty */
 160 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 161 {
 162         int val;
 163         if (get_user(val, arg))
 164                 return -EFAULT;
 165         if (val)
 166                 set_bit(TTY_PTY_LOCK, &tty->flags);
 167         else
 168                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 169         return 0;
 170 }
 171
 172 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
 173 {
 174         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
 175         return put_user(locked, arg);
 176 }
 177
 178 /* Set the packet mode on a pty */
 179 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 180 {
 181         unsigned long flags;
 182         int pktmode;
 183
 184         if (get_user(pktmode, arg))
 185                 return -EFAULT;
 186
 187         spin_lock_irqsave(&tty->ctrl_lock, flags);
 188         if (pktmode) {
 189                 if (!tty->packet) {
 190                         tty->packet = 1;
 191                         tty->link->ctrl_status = 0;
 192                 }
 193         } else
 194                 tty->packet = 0;
 195         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 196
 197         return 0;
 198 }
 199
 200 /* Get the packet mode of a pty */
 201 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
 202 {
 203         int pktmode = tty->packet;
 204         return put_user(pktmode, arg);
 205 }
 206
 207 /* Send a signal to the slave */
 208 static int pty_signal(struct tty_struct *tty, int sig)
 209 {
 210         struct pid *pgrp;
 211
 212         if (tty->link) {
 213                 pgrp = tty_get_pgrp(tty->link);
 214                 if (pgrp)
 215                         kill_pgrp(pgrp, sig, 1);
 216                 put_pid(pgrp);
 217         }
 218         return 0;
 219 }
 220
 221 static void pty_flush_buffer(struct tty_struct *tty)
 222 {
 223         struct tty_struct *to = tty->link;
 224         unsigned long flags;
 225
 226         if (!to)
 227                 return;
 228         /* tty_buffer_flush(to); FIXME */
 229         if (to->packet) {
 230                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 231                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 232                 wake_up_interruptible(&to->read_wait);
 233                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 234         }
 235 }
 236
 237 static int pty_open(struct tty_struct *tty, struct file *filp)
 238 {
 239         if (!tty || !tty->link)
 240                 return -ENODEV;
 241
 242         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 243                 goto out;
 244         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 245                 goto out;
 246         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 247                 goto out;
 248
 249         clear_bit(TTY_IO_ERROR, &tty->flags);
 250         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 251         set_bit(TTY_THROTTLED, &tty->flags);
 252         return 0;
 253
 254 out:
 255         set_bit(TTY_IO_ERROR, &tty->flags);
 256         return -EIO;
 257 }
 258
 259 static void pty_set_termios(struct tty_struct *tty,
 260                                         struct ktermios *old_termios)
 261 {
 262         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 263         tty->termios.c_cflag |= (CS8 | CREAD);
 264 }
 265
 266 /**
 267  *      pty_do_resize           -       resize event
 268  *      @tty: tty being resized
 269  *      @ws: window size being set.
 270  *
 271  *      Update the termios variables and send the necessary signals to
 272  *      peform a terminal resize correctly
 273  */
 274
 275 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 276 {
 277         struct pid *pgrp, *rpgrp;
 278         struct tty_struct *pty = tty->link;
 279
 280         /* For a PTY we need to lock the tty side */
 281         mutex_lock(&tty->winsize_mutex);
 282         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 283                 goto done;
 284
 285         /* Signal the foreground process group of both ptys */
 286         pgrp = tty_get_pgrp(tty);
 287         rpgrp = tty_get_pgrp(pty);
 288
 289         if (pgrp)
 290                 kill_pgrp(pgrp, SIGWINCH, 1);
 291         if (rpgrp != pgrp && rpgrp)
 292                 kill_pgrp(rpgrp, SIGWINCH, 1);
 293
 294         put_pid(pgrp);
 295         put_pid(rpgrp);
 296
 297         tty->winsize = *ws;
 298         pty->winsize = *ws;     /* Never used so will go away soon */
 299 done:
 300         mutex_unlock(&tty->winsize_mutex);
 301         return 0;
 302 }
 303
 304 /**
 305  *      pty_start - start() handler
 306  *      pty_stop  - stop() handler
 307  *      @tty: tty being flow-controlled
 308  *
 309  *      Propagates the TIOCPKT status to the master pty.
 310  *
 311  *      NB: only the master pty can be in packet mode so only the slave
 312  *          needs start()/stop() handlers
 313  */
 314 static void pty_start(struct tty_struct *tty)
 315 {
 316         unsigned long flags;
 317
 318         spin_lock_irqsave(&tty->ctrl_lock, flags);
 319         if (tty->link && tty->link->packet) {
 320                 tty->ctrl_status &= ~TIOCPKT_STOP;
 321                 tty->ctrl_status |= TIOCPKT_START;
 322                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 323         }
 324         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 325 }
 326
 327 static void pty_stop(struct tty_struct *tty)
 328 {
 329         unsigned long flags;
 330
 331         spin_lock_irqsave(&tty->ctrl_lock, flags);
 332         if (tty->link && tty->link->packet) {
 333                 tty->ctrl_status &= ~TIOCPKT_START;
 334                 tty->ctrl_status |= TIOCPKT_STOP;
 335                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 336         }
 337         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 338 }
 339
 340 /**
 341  *      pty_common_install              -       set up the pty pair
 342  *      @driver: the pty driver
 343  *      @tty: the tty being instantiated
 344  *      @legacy: true if this is BSD style
 345  *
 346  *      Perform the initial set up for the tty/pty pair. Called from the
 347  *      tty layer when the port is first opened.
 348  *
 349  *      Locking: the caller must hold the tty_mutex
 350  */
 351 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 352                 bool legacy)
 353 {
 354         struct tty_struct *o_tty;
 355         struct tty_port *ports[2];
 356         int idx = tty->index;
 357         int retval = -ENOMEM;
 358
 359         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 360         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 361         if (!ports[0] || !ports[1])
 362                 goto err;
 363         if (!try_module_get(driver->other->owner)) {
 364                 /* This cannot in fact currently happen */
 365                 goto err;
 366         }
 367         o_tty = alloc_tty_struct(driver->other, idx);
 368         if (!o_tty)
 369                 goto err_put_module;
 370
 371         if (legacy) {
 372                 /* We always use new tty termios data so we can do this
 373                    the easy way .. */
 374                 retval = tty_init_termios(tty);
 375                 if (retval)
 376                         goto err_deinit_tty;
 377
 378                 retval = tty_init_termios(o_tty);
 379                 if (retval)
 380                         goto err_free_termios;
 381
 382                 driver->other->ttys[idx] = o_tty;
 383                 driver->ttys[idx] = tty;
 384         } else {
 385                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 386                 tty->termios = driver->init_termios;
 387                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 388                 o_tty->termios = driver->other->init_termios;
 389         }
 390
 391         /*
 392          * Everything allocated ... set up the o_tty structure.
 393          */
 394         tty_driver_kref_get(driver->other);
 395         if (driver->subtype == PTY_TYPE_MASTER)
 396                 o_tty->count++;
 397         /* Establish the links in both directions */
 398         tty->link   = o_tty;
 399         o_tty->link = tty;
 400         tty_port_init(ports[0]);
 401         tty_port_init(ports[1]);
 402         o_tty->port = ports[0];
 403         tty->port = ports[1];
 404         o_tty->port->itty = o_tty;
 405
 406         tty_driver_kref_get(driver);
 407         tty->count++;
 408         return 0;
 409 err_free_termios:
 410         if (legacy)
 411                 tty_free_termios(tty);
 412 err_deinit_tty:
 413         deinitialize_tty_struct(o_tty);
 414         free_tty_struct(o_tty);
 415 err_put_module:
 416         module_put(driver->other->owner);
 417 err:
 418         kfree(ports[0]);
 419         kfree(ports[1]);
 420         return retval;
 421 }
 422
 423 static void pty_cleanup(struct tty_struct *tty)
 424 {
 425         tty_port_put(tty->port);
 426 }
 427
 428 /* Traditional BSD devices */
 429 #ifdef CONFIG_LEGACY_PTYS
 430
 431 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 432 {
 433         return pty_common_install(driver, tty, true);
 434 }
 435
 436 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 437 {
 438         struct tty_struct *pair = tty->link;
 439         driver->ttys[tty->index] = NULL;
 440         if (pair)
 441                 pair->driver->ttys[pair->index] = NULL;
 442 }
 443
 444 static int pty_bsd_ioctl(struct tty_struct *tty,
 445                          unsigned int cmd, unsigned long arg)
 446 {
 447         switch (cmd) {
 448         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 449                 return pty_set_lock(tty, (int __user *) arg);
 450         case TIOCGPTLCK: /* Get PT Lock status */
 451                 return pty_get_lock(tty, (int __user *)arg);
 452         case TIOCPKT: /* Set PT packet mode */
 453                 return pty_set_pktmode(tty, (int __user *)arg);
 454         case TIOCGPKT: /* Get PT packet mode */
 455                 return pty_get_pktmode(tty, (int __user *)arg);
 456         case TIOCSIG:    /* Send signal to other side of pty */
 457                 return pty_signal(tty, (int) arg);
 458         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 459                 return -EINVAL;
 460         }
 461         return -ENOIOCTLCMD;
 462 }
 463
 464 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 465 module_param(legacy_count, int, 0);
 466
 467 /*
 468  * The master side of a pty can do TIOCSPTLCK and thus
 469  * has pty_bsd_ioctl.
 470  */
 471 static const struct tty_operations master_pty_ops_bsd = {
 472         .install = pty_install,
 473         .open = pty_open,
 474         .close = pty_close,
 475         .write = pty_write,
 476         .write_room = pty_write_room,
 477         .flush_buffer = pty_flush_buffer,
 478         .chars_in_buffer = pty_chars_in_buffer,
 479         .unthrottle = pty_unthrottle,
 480         .ioctl = pty_bsd_ioctl,
 481         .cleanup = pty_cleanup,
 482         .resize = pty_resize,
 483         .remove = pty_remove
 484 };
 485
 486 static const struct tty_operations slave_pty_ops_bsd = {
 487         .install = pty_install,
 488         .open = pty_open,
 489         .close = pty_close,
 490         .write = pty_write,
 491         .write_room = pty_write_room,
 492         .flush_buffer = pty_flush_buffer,
 493         .chars_in_buffer = pty_chars_in_buffer,
 494         .unthrottle = pty_unthrottle,
 495         .set_termios = pty_set_termios,
 496         .cleanup = pty_cleanup,
 497         .resize = pty_resize,
 498         .start = pty_start,
 499         .stop = pty_stop,
 500         .remove = pty_remove
 501 };
 502
 503 static void __init legacy_pty_init(void)
 504 {
 505         struct tty_driver *pty_driver, *pty_slave_driver;
 506
 507         if (legacy_count <= 0)
 508                 return;
 509
 510         pty_driver = tty_alloc_driver(legacy_count,
 511                         TTY_DRIVER_RESET_TERMIOS |
 512                         TTY_DRIVER_REAL_RAW |
 513                         TTY_DRIVER_DYNAMIC_ALLOC);
 514         if (IS_ERR(pty_driver))
 515                 panic("Couldn't allocate pty driver");
 516
 517         pty_slave_driver = tty_alloc_driver(legacy_count,
 518                         TTY_DRIVER_RESET_TERMIOS |
 519                         TTY_DRIVER_REAL_RAW |
 520                         TTY_DRIVER_DYNAMIC_ALLOC);
 521         if (IS_ERR(pty_slave_driver))
 522                 panic("Couldn't allocate pty slave driver");
 523
 524         pty_driver->driver_name = "pty_master";
 525         pty_driver->name = "pty";
 526         pty_driver->major = PTY_MASTER_MAJOR;
 527         pty_driver->minor_start = 0;
 528         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 529         pty_driver->subtype = PTY_TYPE_MASTER;
 530         pty_driver->init_termios = tty_std_termios;
 531         pty_driver->init_termios.c_iflag = 0;
 532         pty_driver->init_termios.c_oflag = 0;
 533         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 534         pty_driver->init_termios.c_lflag = 0;
 535         pty_driver->init_termios.c_ispeed = 38400;
 536         pty_driver->init_termios.c_ospeed = 38400;
 537         pty_driver->other = pty_slave_driver;
 538         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 539
 540         pty_slave_driver->driver_name = "pty_slave";
 541         pty_slave_driver->name = "ttyp";
 542         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 543         pty_slave_driver->minor_start = 0;
 544         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 545         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 546         pty_slave_driver->init_termios = tty_std_termios;
 547         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 548         pty_slave_driver->init_termios.c_ispeed = 38400;
 549         pty_slave_driver->init_termios.c_ospeed = 38400;
 550         pty_slave_driver->other = pty_driver;
 551         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 552
 553         if (tty_register_driver(pty_driver))
 554                 panic("Couldn't register pty driver");
 555         if (tty_register_driver(pty_slave_driver))
 556                 panic("Couldn't register pty slave driver");
 557 }
 558 #else
 559 static inline void legacy_pty_init(void) { }
 560 #endif
 561
 562 /* Unix98 devices */
 563 #ifdef CONFIG_UNIX98_PTYS
 564
 565 static struct cdev ptmx_cdev;
 566
 567 static int pty_unix98_ioctl(struct tty_struct *tty,
 568                             unsigned int cmd, unsigned long arg)
 569 {
 570         switch (cmd) {
 571         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 572                 return pty_set_lock(tty, (int __user *)arg);
 573         case TIOCGPTLCK: /* Get PT Lock status */
 574                 return pty_get_lock(tty, (int __user *)arg);
 575         case TIOCPKT: /* Set PT packet mode */
 576                 return pty_set_pktmode(tty, (int __user *)arg);
 577         case TIOCGPKT: /* Get PT packet mode */
 578                 return pty_get_pktmode(tty, (int __user *)arg);
 579         case TIOCGPTN: /* Get PT Number */
 580                 return put_user(tty->index, (unsigned int __user *)arg);
 581         case TIOCSIG:    /* Send signal to other side of pty */
 582                 return pty_signal(tty, (int) arg);
 583         }
 584
 585         return -ENOIOCTLCMD;
 586 }
 587
 588 /**
 589  *      ptm_unix98_lookup       -       find a pty master
 590  *      @driver: ptm driver
 591  *      @idx: tty index
 592  *
 593  *      Look up a pty master device. Called under the tty_mutex for now.
 594  *      This provides our locking.
 595  */
 596
 597 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 598                 struct inode *ptm_inode, int idx)
 599 {
 600         /* Master must be open via /dev/ptmx */
 601         return ERR_PTR(-EIO);
 602 }
 603
 604 /**
 605  *      pts_unix98_lookup       -       find a pty slave
 606  *      @driver: pts driver
 607  *      @idx: tty index
 608  *
 609  *      Look up a pty master device. Called under the tty_mutex for now.
 610  *      This provides our locking for the tty pointer.
 611  */
 612
 613 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 614                 struct inode *pts_inode, int idx)
 615 {
 616         struct tty_struct *tty;
 617
 618         mutex_lock(&devpts_mutex);
 619         tty = devpts_get_priv(pts_inode);
 620         mutex_unlock(&devpts_mutex);
 621         /* Master must be open before slave */
 622         if (!tty)
 623                 return ERR_PTR(-EIO);
 624         return tty;
 625 }
 626
 627 /* We have no need to install and remove our tty objects as devpts does all
 628    the work for us */
 629
 630 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 631 {
 632         return pty_common_install(driver, tty, false);
 633 }
 634
 635 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 636 {
 637 }
 638
 639 /* this is called once with whichever end is closed last */
 640 static void pty_unix98_shutdown(struct tty_struct *tty)
 641 {
 642         devpts_kill_index(tty->driver_data, tty->index);
 643 }
 644
 645 static const struct tty_operations ptm_unix98_ops = {
 646         .lookup = ptm_unix98_lookup,
 647         .install = pty_unix98_install,
 648         .remove = pty_unix98_remove,
 649         .open = pty_open,
 650         .close = pty_close,
 651         .write = pty_write,
 652         .write_room = pty_write_room,
 653         .flush_buffer = pty_flush_buffer,
 654         .chars_in_buffer = pty_chars_in_buffer,
 655         .unthrottle = pty_unthrottle,
 656         .ioctl = pty_unix98_ioctl,
 657         .resize = pty_resize,
 658         .shutdown = pty_unix98_shutdown,
 659         .cleanup = pty_cleanup
 660 };
 661
 662 static const struct tty_operations pty_unix98_ops = {
 663         .lookup = pts_unix98_lookup,
 664         .install = pty_unix98_install,
 665         .remove = pty_unix98_remove,
 666         .open = pty_open,
 667         .close = pty_close,
 668         .write = pty_write,
 669         .write_room = pty_write_room,
 670         .flush_buffer = pty_flush_buffer,
 671         .chars_in_buffer = pty_chars_in_buffer,
 672         .unthrottle = pty_unthrottle,
 673         .set_termios = pty_set_termios,
 674         .start = pty_start,
 675         .stop = pty_stop,
 676         .shutdown = pty_unix98_shutdown,
 677         .cleanup = pty_cleanup,
 678 };
 679
 680 /**
 681  *      ptmx_open               -       open a unix 98 pty master
 682  *      @inode: inode of device file
 683  *      @filp: file pointer to tty
 684  *
 685  *      Allocate a unix98 pty master device from the ptmx driver.
 686  *
 687  *      Locking: tty_mutex protects the init_dev work. tty->count should
 688  *              protect the rest.
 689  *              allocated_ptys_lock handles the list of free pty numbers
 690  */
 691
 692 static int ptmx_open(struct inode *inode, struct file *filp)
 693 {
 694         struct tty_struct *tty;
 695         struct inode *slave_inode;
 696         int retval;
 697         int index;
 698
 699         nonseekable_open(inode, filp);
 700
 701         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 702         filp->f_mode |= FMODE_NONOTIFY;
 703
 704         retval = tty_alloc_file(filp);
 705         if (retval)
 706                 return retval;
 707
 708         /* find a device that is not in use. */
 709         mutex_lock(&devpts_mutex);
 710         index = devpts_new_index(inode);
 711         if (index < 0) {
 712                 retval = index;
 713                 mutex_unlock(&devpts_mutex);
 714                 goto err_file;
 715         }
 716
 717         mutex_unlock(&devpts_mutex);
 718
 719         mutex_lock(&tty_mutex);
 720         tty = tty_init_dev(ptm_driver, index);
 721
 722         if (IS_ERR(tty)) {
 723                 retval = PTR_ERR(tty);
 724                 goto out;
 725         }
 726
 727         /* The tty returned here is locked so we can safely
 728            drop the mutex */
 729         mutex_unlock(&tty_mutex);
 730
 731         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 732         tty->driver_data = inode;
 733
 734         tty_add_file(tty, filp);
 735
 736         slave_inode = devpts_pty_new(inode,
 737                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 738                         tty->link);
 739         if (IS_ERR(slave_inode)) {
 740                 retval = PTR_ERR(slave_inode);
 741                 goto err_release;
 742         }
 743         tty->link->driver_data = slave_inode;
 744
 745         retval = ptm_driver->ops->open(tty, filp);
 746         if (retval)
 747                 goto err_release;
 748
 749         tty_unlock(tty);
 750         return 0;
 751 err_release:
 752         tty_unlock(tty);
 753         tty_release(inode, filp);
 754         return retval;
 755 out:
 756         mutex_unlock(&tty_mutex);
 757         devpts_kill_index(inode, index);
 758 err_file:
 759         tty_free_file(filp);
 760         return retval;
 761 }
 762
 763 static struct file_operations ptmx_fops;
 764
 765 static void __init unix98_pty_init(void)
 766 {
 767         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 768                         TTY_DRIVER_RESET_TERMIOS |
 769                         TTY_DRIVER_REAL_RAW |
 770                         TTY_DRIVER_DYNAMIC_DEV |
 771                         TTY_DRIVER_DEVPTS_MEM |
 772                         TTY_DRIVER_DYNAMIC_ALLOC);
 773         if (IS_ERR(ptm_driver))
 774                 panic("Couldn't allocate Unix98 ptm driver");
 775         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 776                         TTY_DRIVER_RESET_TERMIOS |
 777                         TTY_DRIVER_REAL_RAW |
 778                         TTY_DRIVER_DYNAMIC_DEV |
 779                         TTY_DRIVER_DEVPTS_MEM |
 780                         TTY_DRIVER_DYNAMIC_ALLOC);
 781         if (IS_ERR(pts_driver))
 782                 panic("Couldn't allocate Unix98 pts driver");
 783
 784         ptm_driver->driver_name = "pty_master";
 785         ptm_driver->name = "ptm";
 786         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 787         ptm_driver->minor_start = 0;
 788         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 789         ptm_driver->subtype = PTY_TYPE_MASTER;
 790         ptm_driver->init_termios = tty_std_termios;
 791         ptm_driver->init_termios.c_iflag = 0;
 792         ptm_driver->init_termios.c_oflag = 0;
 793         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 794         ptm_driver->init_termios.c_lflag = 0;
 795         ptm_driver->init_termios.c_ispeed = 38400;
 796         ptm_driver->init_termios.c_ospeed = 38400;
 797         ptm_driver->other = pts_driver;
 798         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 799
 800         pts_driver->driver_name = "pty_slave";
 801         pts_driver->name = "pts";
 802         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 803         pts_driver->minor_start = 0;
 804         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 805         pts_driver->subtype = PTY_TYPE_SLAVE;
 806         pts_driver->init_termios = tty_std_termios;
 807         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 808         pts_driver->init_termios.c_ispeed = 38400;
 809         pts_driver->init_termios.c_ospeed = 38400;
 810         pts_driver->other = ptm_driver;
 811         tty_set_operations(pts_driver, &pty_unix98_ops);
 812
 813         if (tty_register_driver(ptm_driver))
 814                 panic("Couldn't register Unix98 ptm driver");
 815         if (tty_register_driver(pts_driver))
 816                 panic("Couldn't register Unix98 pts driver");
 817
 818         /* Now create the /dev/ptmx special device */
 819         tty_default_fops(&ptmx_fops);
 820         ptmx_fops.open = ptmx_open;
 821
 822         cdev_init(&ptmx_cdev, &ptmx_fops);
 823         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 824             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 825                 panic("Couldn't register /dev/ptmx driver");
 826         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 827 }
 828
 829 #else
 830 static inline void unix98_pty_init(void) { }
 831 #endif
 832
 833 static int __init pty_init(void)
 834 {
 835         legacy_pty_init();
 836         unix98_pty_init();
 837         return 0;
 838 }
 839 module_init(pty_init);