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
  28
  29 #ifdef CONFIG_UNIX98_PTYS
  30 static struct tty_driver *ptm_driver;
  31 static struct tty_driver *pts_driver;
  32 static DEFINE_MUTEX(devpts_mutex);
  33 #endif
  34
  35 static void pty_close(struct tty_struct *tty, struct file *filp)
  36 {
  37         BUG_ON(!tty);
  38         if (tty->driver->subtype == PTY_TYPE_MASTER)
  39                 WARN_ON(tty->count > 1);
  40         else {
  41                 if (test_bit(TTY_IO_ERROR, &tty->flags))
  42                         return;
  43                 if (tty->count > 2)
  44                         return;
  45         }
  46         set_bit(TTY_IO_ERROR, &tty->flags);
  47         wake_up_interruptible(&tty->read_wait);
  48         wake_up_interruptible(&tty->write_wait);
  49         tty->packet = 0;
  50         /* Review - krefs on tty_link ?? */
  51         if (!tty->link)
  52                 return;
  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                         mutex_lock(&devpts_mutex);
  61                         if (tty->link->driver_data)
  62                                 devpts_pty_kill(tty->link->driver_data);
  63                         mutex_unlock(&devpts_mutex);
  64                 }
  65 #endif
  66                 tty_unlock(tty);
  67                 tty_vhangup(tty->link);
  68                 tty_lock(tty);
  69         }
  70 }
  71
  72 /*
  73  * The unthrottle routine is called by the line discipline to signal
  74  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  75  * flag is always set, to force the line discipline to always call the
  76  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  77  * characters in the queue.  This is necessary since each time this
  78  * happens, we need to wake up any sleeping processes that could be
  79  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  80  * for the pty buffer to be drained.
  81  */
  82 static void pty_unthrottle(struct tty_struct *tty)
  83 {
  84         tty_wakeup(tty->link);
  85         set_bit(TTY_THROTTLED, &tty->flags);
  86 }
  87
  88 /**
  89  *      pty_space       -       report space left for writing
  90  *      @to: tty we are writing into
  91  *
  92  *      Limit the buffer space used by ptys to 8k.
  93  */
  94
  95 static int pty_space(struct tty_struct *to)
  96 {
  97         int n = tty_buffer_space_avail(to->port);
  98         return min(n, 8192);
  99 }
 100
 101 /**
 102  *      pty_write               -       write to a pty
 103  *      @tty: the tty we write from
 104  *      @buf: kernel buffer of data
 105  *      @count: bytes to write
 106  *
 107  *      Our "hardware" write method. Data is coming from the ldisc which
 108  *      may be in a non sleeping state. We simply throw this at the other
 109  *      end of the link as if we were an IRQ handler receiving stuff for
 110  *      the other side of the pty/tty pair.
 111  */
 112
 113 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 114 {
 115         struct tty_struct *to = tty->link;
 116
 117         if (tty->stopped)
 118                 return 0;
 119
 120         if (c > 0) {
 121                 /* Stuff the data into the input queue of the other end */
 122                 c = tty_insert_flip_string(to->port, buf, c);
 123                 /* And shovel */
 124                 if (c)
 125                         tty_flip_buffer_push(to->port);
 126         }
 127         return c;
 128 }
 129
 130 /**
 131  *      pty_write_room  -       write space
 132  *      @tty: tty we are writing from
 133  *
 134  *      Report how many bytes the ldisc can send into the queue for
 135  *      the other device.
 136  */
 137
 138 static int pty_write_room(struct tty_struct *tty)
 139 {
 140         if (tty->stopped)
 141                 return 0;
 142         return pty_space(tty->link);
 143 }
 144
 145 /**
 146  *      pty_chars_in_buffer     -       characters currently in our tx queue
 147  *      @tty: our tty
 148  *
 149  *      Report how much we have in the transmit queue. As everything is
 150  *      instantly at the other end this is easy to implement.
 151  */
 152
 153 static int pty_chars_in_buffer(struct tty_struct *tty)
 154 {
 155         return 0;
 156 }
 157
 158 /* Set the lock flag on a pty */
 159 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 160 {
 161         int val;
 162         if (get_user(val, arg))
 163                 return -EFAULT;
 164         if (val)
 165                 set_bit(TTY_PTY_LOCK, &tty->flags);
 166         else
 167                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 168         return 0;
 169 }
 170
 171 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
 172 {
 173         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
 174         return put_user(locked, arg);
 175 }
 176
 177 /* Set the packet mode on a pty */
 178 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 179 {
 180         unsigned long flags;
 181         int pktmode;
 182
 183         if (get_user(pktmode, arg))
 184                 return -EFAULT;
 185
 186         spin_lock_irqsave(&tty->ctrl_lock, flags);
 187         if (pktmode) {
 188                 if (!tty->packet) {
 189                         tty->packet = 1;
 190                         tty->link->ctrl_status = 0;
 191                 }
 192         } else
 193                 tty->packet = 0;
 194         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 195
 196         return 0;
 197 }
 198
 199 /* Get the packet mode of a pty */
 200 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
 201 {
 202         int pktmode = tty->packet;
 203         return put_user(pktmode, arg);
 204 }
 205
 206 /* Send a signal to the slave */
 207 static int pty_signal(struct tty_struct *tty, int sig)
 208 {
 209         unsigned long flags;
 210         struct pid *pgrp;
 211
 212         if (tty->link) {
 213                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 214                 pgrp = get_pid(tty->link->pgrp);
 215                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 216
 217                 kill_pgrp(pgrp, sig, 1);
 218                 put_pid(pgrp);
 219         }
 220         return 0;
 221 }
 222
 223 static void pty_flush_buffer(struct tty_struct *tty)
 224 {
 225         struct tty_struct *to = tty->link;
 226         unsigned long flags;
 227
 228         if (!to)
 229                 return;
 230         /* tty_buffer_flush(to); FIXME */
 231         if (to->packet) {
 232                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 233                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 234                 wake_up_interruptible(&to->read_wait);
 235                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 236         }
 237 }
 238
 239 static int pty_open(struct tty_struct *tty, struct file *filp)
 240 {
 241         if (!tty || !tty->link)
 242                 return -ENODEV;
 243
 244         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 245                 goto out;
 246         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 247                 goto out;
 248         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 249                 goto out;
 250
 251         clear_bit(TTY_IO_ERROR, &tty->flags);
 252         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 253         set_bit(TTY_THROTTLED, &tty->flags);
 254         return 0;
 255
 256 out:
 257         set_bit(TTY_IO_ERROR, &tty->flags);
 258         return -EIO;
 259 }
 260
 261 static void pty_set_termios(struct tty_struct *tty,
 262                                         struct ktermios *old_termios)
 263 {
 264         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 265         tty->termios.c_cflag |= (CS8 | CREAD);
 266 }
 267
 268 /**
 269  *      pty_do_resize           -       resize event
 270  *      @tty: tty being resized
 271  *      @ws: window size being set.
 272  *
 273  *      Update the termios variables and send the necessary signals to
 274  *      peform a terminal resize correctly
 275  */
 276
 277 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 278 {
 279         struct pid *pgrp, *rpgrp;
 280         unsigned long flags;
 281         struct tty_struct *pty = tty->link;
 282
 283         /* For a PTY we need to lock the tty side */
 284         mutex_lock(&tty->winsize_mutex);
 285         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 286                 goto done;
 287
 288         /* Get the PID values and reference them so we can
 289            avoid holding the tty ctrl lock while sending signals.
 290            We need to lock these individually however. */
 291
 292         spin_lock_irqsave(&tty->ctrl_lock, flags);
 293         pgrp = get_pid(tty->pgrp);
 294         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 295
 296         spin_lock_irqsave(&pty->ctrl_lock, flags);
 297         rpgrp = get_pid(pty->pgrp);
 298         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 299
 300         if (pgrp)
 301                 kill_pgrp(pgrp, SIGWINCH, 1);
 302         if (rpgrp != pgrp && rpgrp)
 303                 kill_pgrp(rpgrp, SIGWINCH, 1);
 304
 305         put_pid(pgrp);
 306         put_pid(rpgrp);
 307
 308         tty->winsize = *ws;
 309         pty->winsize = *ws;     /* Never used so will go away soon */
 310 done:
 311         mutex_unlock(&tty->winsize_mutex);
 312         return 0;
 313 }
 314
 315 /**
 316  *      pty_common_install              -       set up the pty pair
 317  *      @driver: the pty driver
 318  *      @tty: the tty being instantiated
 319  *      @bool: legacy, true if this is BSD style
 320  *
 321  *      Perform the initial set up for the tty/pty pair. Called from the
 322  *      tty layer when the port is first opened.
 323  *
 324  *      Locking: the caller must hold the tty_mutex
 325  */
 326 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 327                 bool legacy)
 328 {
 329         struct tty_struct *o_tty;
 330         struct tty_port *ports[2];
 331         int idx = tty->index;
 332         int retval = -ENOMEM;
 333
 334         o_tty = alloc_tty_struct();
 335         if (!o_tty)
 336                 goto err;
 337         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 338         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 339         if (!ports[0] || !ports[1])
 340                 goto err_free_tty;
 341         if (!try_module_get(driver->other->owner)) {
 342                 /* This cannot in fact currently happen */
 343                 goto err_free_tty;
 344         }
 345         initialize_tty_struct(o_tty, driver->other, idx);
 346
 347         if (legacy) {
 348                 /* We always use new tty termios data so we can do this
 349                    the easy way .. */
 350                 retval = tty_init_termios(tty);
 351                 if (retval)
 352                         goto err_deinit_tty;
 353
 354                 retval = tty_init_termios(o_tty);
 355                 if (retval)
 356                         goto err_free_termios;
 357
 358                 driver->other->ttys[idx] = o_tty;
 359                 driver->ttys[idx] = tty;
 360         } else {
 361                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 362                 tty->termios = driver->init_termios;
 363                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 364                 o_tty->termios = driver->other->init_termios;
 365         }
 366
 367         /*
 368          * Everything allocated ... set up the o_tty structure.
 369          */
 370         tty_driver_kref_get(driver->other);
 371         if (driver->subtype == PTY_TYPE_MASTER)
 372                 o_tty->count++;
 373         /* Establish the links in both directions */
 374         tty->link   = o_tty;
 375         o_tty->link = tty;
 376         tty_port_init(ports[0]);
 377         tty_port_init(ports[1]);
 378         o_tty->port = ports[0];
 379         tty->port = ports[1];
 380         o_tty->port->itty = o_tty;
 381
 382         tty_driver_kref_get(driver);
 383         tty->count++;
 384         return 0;
 385 err_free_termios:
 386         if (legacy)
 387                 tty_free_termios(tty);
 388 err_deinit_tty:
 389         deinitialize_tty_struct(o_tty);
 390         module_put(o_tty->driver->owner);
 391 err_free_tty:
 392         kfree(ports[0]);
 393         kfree(ports[1]);
 394         free_tty_struct(o_tty);
 395 err:
 396         return retval;
 397 }
 398
 399 static void pty_cleanup(struct tty_struct *tty)
 400 {
 401         tty_port_put(tty->port);
 402 }
 403
 404 /* Traditional BSD devices */
 405 #ifdef CONFIG_LEGACY_PTYS
 406
 407 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 408 {
 409         return pty_common_install(driver, tty, true);
 410 }
 411
 412 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 413 {
 414         struct tty_struct *pair = tty->link;
 415         driver->ttys[tty->index] = NULL;
 416         if (pair)
 417                 pair->driver->ttys[pair->index] = NULL;
 418 }
 419
 420 static int pty_bsd_ioctl(struct tty_struct *tty,
 421                          unsigned int cmd, unsigned long arg)
 422 {
 423         switch (cmd) {
 424         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 425                 return pty_set_lock(tty, (int __user *) arg);
 426         case TIOCGPTLCK: /* Get PT Lock status */
 427                 return pty_get_lock(tty, (int __user *)arg);
 428         case TIOCPKT: /* Set PT packet mode */
 429                 return pty_set_pktmode(tty, (int __user *)arg);
 430         case TIOCGPKT: /* Get PT packet mode */
 431                 return pty_get_pktmode(tty, (int __user *)arg);
 432         case TIOCSIG:    /* Send signal to other side of pty */
 433                 return pty_signal(tty, (int) arg);
 434         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 435                 return -EINVAL;
 436         }
 437         return -ENOIOCTLCMD;
 438 }
 439
 440 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 441 module_param(legacy_count, int, 0);
 442
 443 /*
 444  * The master side of a pty can do TIOCSPTLCK and thus
 445  * has pty_bsd_ioctl.
 446  */
 447 static const struct tty_operations master_pty_ops_bsd = {
 448         .install = pty_install,
 449         .open = pty_open,
 450         .close = pty_close,
 451         .write = pty_write,
 452         .write_room = pty_write_room,
 453         .flush_buffer = pty_flush_buffer,
 454         .chars_in_buffer = pty_chars_in_buffer,
 455         .unthrottle = pty_unthrottle,
 456         .set_termios = pty_set_termios,
 457         .ioctl = pty_bsd_ioctl,
 458         .cleanup = pty_cleanup,
 459         .resize = pty_resize,
 460         .remove = pty_remove
 461 };
 462
 463 static const struct tty_operations slave_pty_ops_bsd = {
 464         .install = pty_install,
 465         .open = pty_open,
 466         .close = pty_close,
 467         .write = pty_write,
 468         .write_room = pty_write_room,
 469         .flush_buffer = pty_flush_buffer,
 470         .chars_in_buffer = pty_chars_in_buffer,
 471         .unthrottle = pty_unthrottle,
 472         .set_termios = pty_set_termios,
 473         .cleanup = pty_cleanup,
 474         .resize = pty_resize,
 475         .remove = pty_remove
 476 };
 477
 478 static void __init legacy_pty_init(void)
 479 {
 480         struct tty_driver *pty_driver, *pty_slave_driver;
 481
 482         if (legacy_count <= 0)
 483                 return;
 484
 485         pty_driver = tty_alloc_driver(legacy_count,
 486                         TTY_DRIVER_RESET_TERMIOS |
 487                         TTY_DRIVER_REAL_RAW |
 488                         TTY_DRIVER_DYNAMIC_ALLOC);
 489         if (IS_ERR(pty_driver))
 490                 panic("Couldn't allocate pty driver");
 491
 492         pty_slave_driver = tty_alloc_driver(legacy_count,
 493                         TTY_DRIVER_RESET_TERMIOS |
 494                         TTY_DRIVER_REAL_RAW |
 495                         TTY_DRIVER_DYNAMIC_ALLOC);
 496         if (IS_ERR(pty_slave_driver))
 497                 panic("Couldn't allocate pty slave driver");
 498
 499         pty_driver->driver_name = "pty_master";
 500         pty_driver->name = "pty";
 501         pty_driver->major = PTY_MASTER_MAJOR;
 502         pty_driver->minor_start = 0;
 503         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 504         pty_driver->subtype = PTY_TYPE_MASTER;
 505         pty_driver->init_termios = tty_std_termios;
 506         pty_driver->init_termios.c_iflag = 0;
 507         pty_driver->init_termios.c_oflag = 0;
 508         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 509         pty_driver->init_termios.c_lflag = 0;
 510         pty_driver->init_termios.c_ispeed = 38400;
 511         pty_driver->init_termios.c_ospeed = 38400;
 512         pty_driver->other = pty_slave_driver;
 513         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 514
 515         pty_slave_driver->driver_name = "pty_slave";
 516         pty_slave_driver->name = "ttyp";
 517         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 518         pty_slave_driver->minor_start = 0;
 519         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 520         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 521         pty_slave_driver->init_termios = tty_std_termios;
 522         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 523         pty_slave_driver->init_termios.c_ispeed = 38400;
 524         pty_slave_driver->init_termios.c_ospeed = 38400;
 525         pty_slave_driver->other = pty_driver;
 526         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 527
 528         if (tty_register_driver(pty_driver))
 529                 panic("Couldn't register pty driver");
 530         if (tty_register_driver(pty_slave_driver))
 531                 panic("Couldn't register pty slave driver");
 532 }
 533 #else
 534 static inline void legacy_pty_init(void) { }
 535 #endif
 536
 537 /* Unix98 devices */
 538 #ifdef CONFIG_UNIX98_PTYS
 539
 540 static struct cdev ptmx_cdev;
 541
 542 static int pty_unix98_ioctl(struct tty_struct *tty,
 543                             unsigned int cmd, unsigned long arg)
 544 {
 545         switch (cmd) {
 546         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 547                 return pty_set_lock(tty, (int __user *)arg);
 548         case TIOCGPTLCK: /* Get PT Lock status */
 549                 return pty_get_lock(tty, (int __user *)arg);
 550         case TIOCPKT: /* Set PT packet mode */
 551                 return pty_set_pktmode(tty, (int __user *)arg);
 552         case TIOCGPKT: /* Get PT packet mode */
 553                 return pty_get_pktmode(tty, (int __user *)arg);
 554         case TIOCGPTN: /* Get PT Number */
 555                 return put_user(tty->index, (unsigned int __user *)arg);
 556         case TIOCSIG:    /* Send signal to other side of pty */
 557                 return pty_signal(tty, (int) arg);
 558         }
 559
 560         return -ENOIOCTLCMD;
 561 }
 562
 563 /**
 564  *      ptm_unix98_lookup       -       find a pty master
 565  *      @driver: ptm driver
 566  *      @idx: tty index
 567  *
 568  *      Look up a pty master device. Called under the tty_mutex for now.
 569  *      This provides our locking.
 570  */
 571
 572 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 573                 struct inode *ptm_inode, int idx)
 574 {
 575         /* Master must be open via /dev/ptmx */
 576         return ERR_PTR(-EIO);
 577 }
 578
 579 /**
 580  *      pts_unix98_lookup       -       find a pty slave
 581  *      @driver: pts driver
 582  *      @idx: tty index
 583  *
 584  *      Look up a pty master device. Called under the tty_mutex for now.
 585  *      This provides our locking for the tty pointer.
 586  */
 587
 588 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 589                 struct inode *pts_inode, int idx)
 590 {
 591         struct tty_struct *tty;
 592
 593         mutex_lock(&devpts_mutex);
 594         tty = devpts_get_priv(pts_inode);
 595         mutex_unlock(&devpts_mutex);
 596         /* Master must be open before slave */
 597         if (!tty)
 598                 return ERR_PTR(-EIO);
 599         return tty;
 600 }
 601
 602 /* We have no need to install and remove our tty objects as devpts does all
 603    the work for us */
 604
 605 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 606 {
 607         return pty_common_install(driver, tty, false);
 608 }
 609
 610 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 611 {
 612 }
 613
 614 /* this is called once with whichever end is closed last */
 615 static void pty_unix98_shutdown(struct tty_struct *tty)
 616 {
 617         devpts_kill_index(tty->driver_data, tty->index);
 618 }
 619
 620 static const struct tty_operations ptm_unix98_ops = {
 621         .lookup = ptm_unix98_lookup,
 622         .install = pty_unix98_install,
 623         .remove = pty_unix98_remove,
 624         .open = pty_open,
 625         .close = pty_close,
 626         .write = pty_write,
 627         .write_room = pty_write_room,
 628         .flush_buffer = pty_flush_buffer,
 629         .chars_in_buffer = pty_chars_in_buffer,
 630         .unthrottle = pty_unthrottle,
 631         .set_termios = pty_set_termios,
 632         .ioctl = pty_unix98_ioctl,
 633         .resize = pty_resize,
 634         .shutdown = pty_unix98_shutdown,
 635         .cleanup = pty_cleanup
 636 };
 637
 638 static const struct tty_operations pty_unix98_ops = {
 639         .lookup = pts_unix98_lookup,
 640         .install = pty_unix98_install,
 641         .remove = pty_unix98_remove,
 642         .open = pty_open,
 643         .close = pty_close,
 644         .write = pty_write,
 645         .write_room = pty_write_room,
 646         .flush_buffer = pty_flush_buffer,
 647         .chars_in_buffer = pty_chars_in_buffer,
 648         .unthrottle = pty_unthrottle,
 649         .set_termios = pty_set_termios,
 650         .shutdown = pty_unix98_shutdown,
 651         .cleanup = pty_cleanup,
 652 };
 653
 654 /**
 655  *      ptmx_open               -       open a unix 98 pty master
 656  *      @inode: inode of device file
 657  *      @filp: file pointer to tty
 658  *
 659  *      Allocate a unix98 pty master device from the ptmx driver.
 660  *
 661  *      Locking: tty_mutex protects the init_dev work. tty->count should
 662  *              protect the rest.
 663  *              allocated_ptys_lock handles the list of free pty numbers
 664  */
 665
 666 static int ptmx_open(struct inode *inode, struct file *filp)
 667 {
 668         struct tty_struct *tty;
 669         struct inode *slave_inode;
 670         int retval;
 671         int index;
 672
 673         nonseekable_open(inode, filp);
 674
 675         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 676         filp->f_mode |= FMODE_NONOTIFY;
 677
 678         retval = tty_alloc_file(filp);
 679         if (retval)
 680                 return retval;
 681
 682         /* find a device that is not in use. */
 683         mutex_lock(&devpts_mutex);
 684         index = devpts_new_index(inode);
 685         if (index < 0) {
 686                 retval = index;
 687                 mutex_unlock(&devpts_mutex);
 688                 goto err_file;
 689         }
 690
 691         mutex_unlock(&devpts_mutex);
 692
 693         mutex_lock(&tty_mutex);
 694         tty = tty_init_dev(ptm_driver, index);
 695
 696         if (IS_ERR(tty)) {
 697                 retval = PTR_ERR(tty);
 698                 goto out;
 699         }
 700
 701         /* The tty returned here is locked so we can safely
 702            drop the mutex */
 703         mutex_unlock(&tty_mutex);
 704
 705         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 706         tty->driver_data = inode;
 707
 708         tty_add_file(tty, filp);
 709
 710         slave_inode = devpts_pty_new(inode,
 711                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 712                         tty->link);
 713         if (IS_ERR(slave_inode)) {
 714                 retval = PTR_ERR(slave_inode);
 715                 goto err_release;
 716         }
 717         tty->link->driver_data = slave_inode;
 718
 719         retval = ptm_driver->ops->open(tty, filp);
 720         if (retval)
 721                 goto err_release;
 722
 723         tty_unlock(tty);
 724         return 0;
 725 err_release:
 726         tty_unlock(tty);
 727         tty_release(inode, filp);
 728         return retval;
 729 out:
 730         mutex_unlock(&tty_mutex);
 731         devpts_kill_index(inode, index);
 732 err_file:
 733         tty_free_file(filp);
 734         return retval;
 735 }
 736
 737 static struct file_operations ptmx_fops;
 738
 739 static void __init unix98_pty_init(void)
 740 {
 741         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 742                         TTY_DRIVER_RESET_TERMIOS |
 743                         TTY_DRIVER_REAL_RAW |
 744                         TTY_DRIVER_DYNAMIC_DEV |
 745                         TTY_DRIVER_DEVPTS_MEM |
 746                         TTY_DRIVER_DYNAMIC_ALLOC);
 747         if (IS_ERR(ptm_driver))
 748                 panic("Couldn't allocate Unix98 ptm driver");
 749         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 750                         TTY_DRIVER_RESET_TERMIOS |
 751                         TTY_DRIVER_REAL_RAW |
 752                         TTY_DRIVER_DYNAMIC_DEV |
 753                         TTY_DRIVER_DEVPTS_MEM |
 754                         TTY_DRIVER_DYNAMIC_ALLOC);
 755         if (IS_ERR(pts_driver))
 756                 panic("Couldn't allocate Unix98 pts driver");
 757
 758         ptm_driver->driver_name = "pty_master";
 759         ptm_driver->name = "ptm";
 760         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 761         ptm_driver->minor_start = 0;
 762         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 763         ptm_driver->subtype = PTY_TYPE_MASTER;
 764         ptm_driver->init_termios = tty_std_termios;
 765         ptm_driver->init_termios.c_iflag = 0;
 766         ptm_driver->init_termios.c_oflag = 0;
 767         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 768         ptm_driver->init_termios.c_lflag = 0;
 769         ptm_driver->init_termios.c_ispeed = 38400;
 770         ptm_driver->init_termios.c_ospeed = 38400;
 771         ptm_driver->other = pts_driver;
 772         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 773
 774         pts_driver->driver_name = "pty_slave";
 775         pts_driver->name = "pts";
 776         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 777         pts_driver->minor_start = 0;
 778         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 779         pts_driver->subtype = PTY_TYPE_SLAVE;
 780         pts_driver->init_termios = tty_std_termios;
 781         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 782         pts_driver->init_termios.c_ispeed = 38400;
 783         pts_driver->init_termios.c_ospeed = 38400;
 784         pts_driver->other = ptm_driver;
 785         tty_set_operations(pts_driver, &pty_unix98_ops);
 786
 787         if (tty_register_driver(ptm_driver))
 788                 panic("Couldn't register Unix98 ptm driver");
 789         if (tty_register_driver(pts_driver))
 790                 panic("Couldn't register Unix98 pts driver");
 791
 792         /* Now create the /dev/ptmx special device */
 793         tty_default_fops(&ptmx_fops);
 794         ptmx_fops.open = ptmx_open;
 795
 796         cdev_init(&ptmx_cdev, &ptmx_fops);
 797         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 798             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 799                 panic("Couldn't register /dev/ptmx driver");
 800         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 801 }
 802
 803 #else
 804 static inline void unix98_pty_init(void) { }
 805 #endif
 806
 807 static int __init pty_init(void)
 808 {
 809         legacy_pty_init();
 810         unix98_pty_init();
 811         return 0;
 812 }
 813 module_init(pty_init);