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