drivers/char/pty.c

   1 /*
   2  *  linux/drivers/char/pty.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added support for a Unix98-style ptmx device.
   7  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   8  *
   9  *  When reading this code see also fs/devpts. In particular note that the
  10  *  driver_data field is used by the devpts side as a binding to the devpts
  11  *  inode.
  12  */
  13
  14 #include <linux/module.h>
  15
  16 #include <linux/errno.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_flip.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/sched.h>
  22 #include <linux/string.h>
  23 #include <linux/major.h>
  24 #include <linux/mm.h>
  25 #include <linux/init.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/sysctl.h>
  28 #include <linux/device.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/bitops.h>
  31 #include <linux/devpts_fs.h>
  32
  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_vhangup(tty->link);
  65         }
  66 }
  67
  68 /*
  69  * The unthrottle routine is called by the line discipline to signal
  70  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  71  * flag is always set, to force the line discipline to always call the
  72  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  73  * characters in the queue.  This is necessary since each time this
  74  * happens, we need to wake up any sleeping processes that could be
  75  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  76  * for the pty buffer to be drained.
  77  */
  78 static void pty_unthrottle(struct tty_struct *tty)
  79 {
  80         tty_wakeup(tty->link);
  81         set_bit(TTY_THROTTLED, &tty->flags);
  82 }
  83
  84 /**
  85  *      pty_space       -       report space left for writing
  86  *      @to: tty we are writing into
  87  *
  88  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  89  *      allows a lot of overspill room for echo and other fun messes to
  90  *      be handled properly
  91  */
  92
  93 static int pty_space(struct tty_struct *to)
  94 {
  95         int n = 8192 - to->buf.memory_used;
  96         if (n < 0)
  97                 return 0;
  98         return n;
  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, buf, c);
 123                 /* And shovel */
 124                 if (c) {
 125                         tty_flip_buffer_push(to);
 126                         tty_wakeup(tty);
 127                 }
 128         }
 129         return c;
 130 }
 131
 132 /**
 133  *      pty_write_room  -       write space
 134  *      @tty: tty we are writing from
 135  *
 136  *      Report how many bytes the ldisc can send into the queue for
 137  *      the other device.
 138  */
 139
 140 static int pty_write_room(struct tty_struct *tty)
 141 {
 142         if (tty->stopped)
 143                 return 0;
 144         return pty_space(tty->link);
 145 }
 146
 147 /**
 148  *      pty_chars_in_buffer     -       characters currently in our tx queue
 149  *      @tty: our tty
 150  *
 151  *      Report how much we have in the transmit queue. As everything is
 152  *      instantly at the other end this is easy to implement.
 153  */
 154
 155 static int pty_chars_in_buffer(struct tty_struct *tty)
 156 {
 157         return 0;
 158 }
 159
 160 /* Set the lock flag on a pty */
 161 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 162 {
 163         int val;
 164         if (get_user(val, arg))
 165                 return -EFAULT;
 166         if (val)
 167                 set_bit(TTY_PTY_LOCK, &tty->flags);
 168         else
 169                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 170         return 0;
 171 }
 172
 173 static void pty_flush_buffer(struct tty_struct *tty)
 174 {
 175         struct tty_struct *to = tty->link;
 176         unsigned long flags;
 177
 178         if (!to)
 179                 return;
 180         /* tty_buffer_flush(to); FIXME */
 181         if (to->packet) {
 182                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 183                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 184                 wake_up_interruptible(&to->read_wait);
 185                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 186         }
 187 }
 188
 189 static int pty_open(struct tty_struct *tty, struct file *filp)
 190 {
 191         int     retval = -ENODEV;
 192
 193         if (!tty || !tty->link)
 194                 goto out;
 195
 196         retval = -EIO;
 197         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 198                 goto out;
 199         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 200                 goto out;
 201         if (tty->link->count != 1)
 202                 goto out;
 203
 204         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 205         set_bit(TTY_THROTTLED, &tty->flags);
 206         retval = 0;
 207 out:
 208         return retval;
 209 }
 210
 211 static void pty_set_termios(struct tty_struct *tty,
 212                                         struct ktermios *old_termios)
 213 {
 214         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 215         tty->termios->c_cflag |= (CS8 | CREAD);
 216 }
 217
 218 /**
 219  *      pty_do_resize           -       resize event
 220  *      @tty: tty being resized
 221  *      @ws: window size being set.
 222  *
 223  *      Update the termios variables and send the neccessary signals to
 224  *      peform a terminal resize correctly
 225  */
 226
 227 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 228 {
 229         struct pid *pgrp, *rpgrp;
 230         unsigned long flags;
 231         struct tty_struct *pty = tty->link;
 232
 233         /* For a PTY we need to lock the tty side */
 234         mutex_lock(&tty->termios_mutex);
 235         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 236                 goto done;
 237
 238         /* Get the PID values and reference them so we can
 239            avoid holding the tty ctrl lock while sending signals.
 240            We need to lock these individually however. */
 241
 242         spin_lock_irqsave(&tty->ctrl_lock, flags);
 243         pgrp = get_pid(tty->pgrp);
 244         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 245
 246         spin_lock_irqsave(&pty->ctrl_lock, flags);
 247         rpgrp = get_pid(pty->pgrp);
 248         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 249
 250         if (pgrp)
 251                 kill_pgrp(pgrp, SIGWINCH, 1);
 252         if (rpgrp != pgrp && rpgrp)
 253                 kill_pgrp(rpgrp, SIGWINCH, 1);
 254
 255         put_pid(pgrp);
 256         put_pid(rpgrp);
 257
 258         tty->winsize = *ws;
 259         pty->winsize = *ws;     /* Never used so will go away soon */
 260 done:
 261         mutex_unlock(&tty->termios_mutex);
 262         return 0;
 263 }
 264
 265 /* Traditional BSD devices */
 266 #ifdef CONFIG_LEGACY_PTYS
 267
 268 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 269 {
 270         struct tty_struct *o_tty;
 271         int idx = tty->index;
 272         int retval;
 273
 274         o_tty = alloc_tty_struct();
 275         if (!o_tty)
 276                 return -ENOMEM;
 277         if (!try_module_get(driver->other->owner)) {
 278                 /* This cannot in fact currently happen */
 279                 free_tty_struct(o_tty);
 280                 return -ENOMEM;
 281         }
 282         initialize_tty_struct(o_tty, driver->other, idx);
 283
 284         /* We always use new tty termios data so we can do this
 285            the easy way .. */
 286         retval = tty_init_termios(tty);
 287         if (retval)
 288                 goto free_mem_out;
 289
 290         retval = tty_init_termios(o_tty);
 291         if (retval) {
 292                 tty_free_termios(tty);
 293                 goto free_mem_out;
 294         }
 295
 296         /*
 297          * Everything allocated ... set up the o_tty structure.
 298          */
 299         driver->other->ttys[idx] = o_tty;
 300         tty_driver_kref_get(driver->other);
 301         if (driver->subtype == PTY_TYPE_MASTER)
 302                 o_tty->count++;
 303         /* Establish the links in both directions */
 304         tty->link   = o_tty;
 305         o_tty->link = tty;
 306
 307         tty_driver_kref_get(driver);
 308         tty->count++;
 309         driver->ttys[idx] = tty;
 310         return 0;
 311 free_mem_out:
 312         module_put(o_tty->driver->owner);
 313         free_tty_struct(o_tty);
 314         return -ENOMEM;
 315 }
 316
 317 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 318                          unsigned int cmd, unsigned long arg)
 319 {
 320         switch (cmd) {
 321         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 322                 return pty_set_lock(tty, (int __user *) arg);
 323         }
 324         return -ENOIOCTLCMD;
 325 }
 326
 327 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 328 module_param(legacy_count, int, 0);
 329
 330 /*
 331  * The master side of a pty can do TIOCSPTLCK and thus
 332  * has pty_bsd_ioctl.
 333  */
 334 static const struct tty_operations master_pty_ops_bsd = {
 335         .install = pty_install,
 336         .open = pty_open,
 337         .close = pty_close,
 338         .write = pty_write,
 339         .write_room = pty_write_room,
 340         .flush_buffer = pty_flush_buffer,
 341         .chars_in_buffer = pty_chars_in_buffer,
 342         .unthrottle = pty_unthrottle,
 343         .set_termios = pty_set_termios,
 344         .ioctl = pty_bsd_ioctl,
 345         .resize = pty_resize
 346 };
 347
 348 static const struct tty_operations slave_pty_ops_bsd = {
 349         .install = pty_install,
 350         .open = pty_open,
 351         .close = pty_close,
 352         .write = pty_write,
 353         .write_room = pty_write_room,
 354         .flush_buffer = pty_flush_buffer,
 355         .chars_in_buffer = pty_chars_in_buffer,
 356         .unthrottle = pty_unthrottle,
 357         .set_termios = pty_set_termios,
 358         .resize = pty_resize
 359 };
 360
 361 static void __init legacy_pty_init(void)
 362 {
 363         struct tty_driver *pty_driver, *pty_slave_driver;
 364
 365         if (legacy_count <= 0)
 366                 return;
 367
 368         pty_driver = alloc_tty_driver(legacy_count);
 369         if (!pty_driver)
 370                 panic("Couldn't allocate pty driver");
 371
 372         pty_slave_driver = alloc_tty_driver(legacy_count);
 373         if (!pty_slave_driver)
 374                 panic("Couldn't allocate pty slave driver");
 375
 376         pty_driver->owner = THIS_MODULE;
 377         pty_driver->driver_name = "pty_master";
 378         pty_driver->name = "pty";
 379         pty_driver->major = PTY_MASTER_MAJOR;
 380         pty_driver->minor_start = 0;
 381         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 382         pty_driver->subtype = PTY_TYPE_MASTER;
 383         pty_driver->init_termios = tty_std_termios;
 384         pty_driver->init_termios.c_iflag = 0;
 385         pty_driver->init_termios.c_oflag = 0;
 386         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 387         pty_driver->init_termios.c_lflag = 0;
 388         pty_driver->init_termios.c_ispeed = 38400;
 389         pty_driver->init_termios.c_ospeed = 38400;
 390         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 391         pty_driver->other = pty_slave_driver;
 392         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 393
 394         pty_slave_driver->owner = THIS_MODULE;
 395         pty_slave_driver->driver_name = "pty_slave";
 396         pty_slave_driver->name = "ttyp";
 397         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 398         pty_slave_driver->minor_start = 0;
 399         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 400         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 401         pty_slave_driver->init_termios = tty_std_termios;
 402         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 403         pty_slave_driver->init_termios.c_ispeed = 38400;
 404         pty_slave_driver->init_termios.c_ospeed = 38400;
 405         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 406                                         TTY_DRIVER_REAL_RAW;
 407         pty_slave_driver->other = pty_driver;
 408         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 409
 410         if (tty_register_driver(pty_driver))
 411                 panic("Couldn't register pty driver");
 412         if (tty_register_driver(pty_slave_driver))
 413                 panic("Couldn't register pty slave driver");
 414 }
 415 #else
 416 static inline void legacy_pty_init(void) { }
 417 #endif
 418
 419 /* Unix98 devices */
 420 #ifdef CONFIG_UNIX98_PTYS
 421 /*
 422  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 423  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 424  */
 425 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 426 static int pty_limit_min;
 427 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 428 static int pty_count;
 429
 430 static struct cdev ptmx_cdev;
 431
 432 static struct ctl_table pty_table[] = {
 433         {
 434                 .procname       = "max",
 435                 .maxlen         = sizeof(int),
 436                 .mode           = 0644,
 437                 .data           = &pty_limit,
 438                 .proc_handler   = proc_dointvec_minmax,
 439                 .extra1         = &pty_limit_min,
 440                 .extra2         = &pty_limit_max,
 441         }, {
 442                 .procname       = "nr",
 443                 .maxlen         = sizeof(int),
 444                 .mode           = 0444,
 445                 .data           = &pty_count,
 446                 .proc_handler   = proc_dointvec,
 447         },
 448         {}
 449 };
 450
 451 static struct ctl_table pty_kern_table[] = {
 452         {
 453                 .procname       = "pty",
 454                 .mode           = 0555,
 455                 .child          = pty_table,
 456         },
 457         {}
 458 };
 459
 460 static struct ctl_table pty_root_table[] = {
 461         {
 462                 .procname       = "kernel",
 463                 .mode           = 0555,
 464                 .child          = pty_kern_table,
 465         },
 466         {}
 467 };
 468
 469
 470 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 471                             unsigned int cmd, unsigned long arg)
 472 {
 473         switch (cmd) {
 474         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 475                 return pty_set_lock(tty, (int __user *)arg);
 476         case TIOCGPTN: /* Get PT Number */
 477                 return put_user(tty->index, (unsigned int __user *)arg);
 478         }
 479
 480         return -ENOIOCTLCMD;
 481 }
 482
 483 /**
 484  *      ptm_unix98_lookup       -       find a pty master
 485  *      @driver: ptm driver
 486  *      @idx: tty index
 487  *
 488  *      Look up a pty master device. Called under the tty_mutex for now.
 489  *      This provides our locking.
 490  */
 491
 492 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 493                 struct inode *ptm_inode, int idx)
 494 {
 495         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 496         if (tty)
 497                 tty = tty->link;
 498         return tty;
 499 }
 500
 501 /**
 502  *      pts_unix98_lookup       -       find a pty slave
 503  *      @driver: pts driver
 504  *      @idx: tty index
 505  *
 506  *      Look up a pty master device. Called under the tty_mutex for now.
 507  *      This provides our locking.
 508  */
 509
 510 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 511                 struct inode *pts_inode, int idx)
 512 {
 513         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 514         /* Master must be open before slave */
 515         if (!tty)
 516                 return ERR_PTR(-EIO);
 517         return tty;
 518 }
 519
 520 static void pty_unix98_shutdown(struct tty_struct *tty)
 521 {
 522         /* We have our own method as we don't use the tty index */
 523         kfree(tty->termios);
 524 }
 525
 526 /* We have no need to install and remove our tty objects as devpts does all
 527    the work for us */
 528
 529 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 530 {
 531         struct tty_struct *o_tty;
 532         int idx = tty->index;
 533
 534         o_tty = alloc_tty_struct();
 535         if (!o_tty)
 536                 return -ENOMEM;
 537         if (!try_module_get(driver->other->owner)) {
 538                 /* This cannot in fact currently happen */
 539                 free_tty_struct(o_tty);
 540                 return -ENOMEM;
 541         }
 542         initialize_tty_struct(o_tty, driver->other, idx);
 543
 544         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 545         if (tty->termios == NULL)
 546                 goto free_mem_out;
 547         *tty->termios = driver->init_termios;
 548         tty->termios_locked = tty->termios + 1;
 549
 550         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 551         if (o_tty->termios == NULL)
 552                 goto free_mem_out;
 553         *o_tty->termios = driver->other->init_termios;
 554         o_tty->termios_locked = o_tty->termios + 1;
 555
 556         tty_driver_kref_get(driver->other);
 557         if (driver->subtype == PTY_TYPE_MASTER)
 558                 o_tty->count++;
 559         /* Establish the links in both directions */
 560         tty->link   = o_tty;
 561         o_tty->link = tty;
 562         /*
 563          * All structures have been allocated, so now we install them.
 564          * Failures after this point use release_tty to clean up, so
 565          * there's no need to null out the local pointers.
 566          */
 567         tty_driver_kref_get(driver);
 568         tty->count++;
 569         pty_count++;
 570         return 0;
 571 free_mem_out:
 572         kfree(o_tty->termios);
 573         module_put(o_tty->driver->owner);
 574         free_tty_struct(o_tty);
 575         kfree(tty->termios);
 576         return -ENOMEM;
 577 }
 578
 579 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 580 {
 581         pty_count--;
 582 }
 583
 584 static const struct tty_operations ptm_unix98_ops = {
 585         .lookup = ptm_unix98_lookup,
 586         .install = pty_unix98_install,
 587         .remove = pty_unix98_remove,
 588         .open = pty_open,
 589         .close = pty_close,
 590         .write = pty_write,
 591         .write_room = pty_write_room,
 592         .flush_buffer = pty_flush_buffer,
 593         .chars_in_buffer = pty_chars_in_buffer,
 594         .unthrottle = pty_unthrottle,
 595         .set_termios = pty_set_termios,
 596         .ioctl = pty_unix98_ioctl,
 597         .shutdown = pty_unix98_shutdown,
 598         .resize = pty_resize
 599 };
 600
 601 static const struct tty_operations pty_unix98_ops = {
 602         .lookup = pts_unix98_lookup,
 603         .install = pty_unix98_install,
 604         .remove = pty_unix98_remove,
 605         .open = pty_open,
 606         .close = pty_close,
 607         .write = pty_write,
 608         .write_room = pty_write_room,
 609         .flush_buffer = pty_flush_buffer,
 610         .chars_in_buffer = pty_chars_in_buffer,
 611         .unthrottle = pty_unthrottle,
 612         .set_termios = pty_set_termios,
 613         .shutdown = pty_unix98_shutdown
 614 };
 615
 616 /**
 617  *      ptmx_open               -       open a unix 98 pty master
 618  *      @inode: inode of device file
 619  *      @filp: file pointer to tty
 620  *
 621  *      Allocate a unix98 pty master device from the ptmx driver.
 622  *
 623  *      Locking: tty_mutex protects the init_dev work. tty->count should
 624  *              protect the rest.
 625  *              allocated_ptys_lock handles the list of free pty numbers
 626  */
 627
 628 static int __ptmx_open(struct inode *inode, struct file *filp)
 629 {
 630         struct tty_struct *tty;
 631         int retval;
 632         int index;
 633
 634         nonseekable_open(inode, filp);
 635
 636         /* find a device that is not in use. */
 637         index = devpts_new_index(inode);
 638         if (index < 0)
 639                 return index;
 640
 641         mutex_lock(&tty_mutex);
 642         tty = tty_init_dev(ptm_driver, index, 1);
 643         mutex_unlock(&tty_mutex);
 644
 645         if (IS_ERR(tty)) {
 646                 retval = PTR_ERR(tty);
 647                 goto out;
 648         }
 649
 650         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 651         filp->private_data = tty;
 652         file_move(filp, &tty->tty_files);
 653
 654         retval = devpts_pty_new(inode, tty->link);
 655         if (retval)
 656                 goto out1;
 657
 658         retval = ptm_driver->ops->open(tty, filp);
 659         if (!retval)
 660                 return 0;
 661 out1:
 662         tty_release(inode, filp);
 663         return retval;
 664 out:
 665         devpts_kill_index(inode, index);
 666         return retval;
 667 }
 668
 669 static int ptmx_open(struct inode *inode, struct file *filp)
 670 {
 671         int ret;
 672
 673         lock_kernel();
 674         ret = __ptmx_open(inode, filp);
 675         unlock_kernel();
 676         return ret;
 677 }
 678
 679 static struct file_operations ptmx_fops;
 680
 681 static void __init unix98_pty_init(void)
 682 {
 683         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 684         if (!ptm_driver)
 685                 panic("Couldn't allocate Unix98 ptm driver");
 686         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 687         if (!pts_driver)
 688                 panic("Couldn't allocate Unix98 pts driver");
 689
 690         ptm_driver->owner = THIS_MODULE;
 691         ptm_driver->driver_name = "pty_master";
 692         ptm_driver->name = "ptm";
 693         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 694         ptm_driver->minor_start = 0;
 695         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 696         ptm_driver->subtype = PTY_TYPE_MASTER;
 697         ptm_driver->init_termios = tty_std_termios;
 698         ptm_driver->init_termios.c_iflag = 0;
 699         ptm_driver->init_termios.c_oflag = 0;
 700         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 701         ptm_driver->init_termios.c_lflag = 0;
 702         ptm_driver->init_termios.c_ispeed = 38400;
 703         ptm_driver->init_termios.c_ospeed = 38400;
 704         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 705                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 706         ptm_driver->other = pts_driver;
 707         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 708
 709         pts_driver->owner = THIS_MODULE;
 710         pts_driver->driver_name = "pty_slave";
 711         pts_driver->name = "pts";
 712         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 713         pts_driver->minor_start = 0;
 714         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 715         pts_driver->subtype = PTY_TYPE_SLAVE;
 716         pts_driver->init_termios = tty_std_termios;
 717         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 718         pts_driver->init_termios.c_ispeed = 38400;
 719         pts_driver->init_termios.c_ospeed = 38400;
 720         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 721                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 722         pts_driver->other = ptm_driver;
 723         tty_set_operations(pts_driver, &pty_unix98_ops);
 724
 725         if (tty_register_driver(ptm_driver))
 726                 panic("Couldn't register Unix98 ptm driver");
 727         if (tty_register_driver(pts_driver))
 728                 panic("Couldn't register Unix98 pts driver");
 729
 730         register_sysctl_table(pty_root_table);
 731
 732         /* Now create the /dev/ptmx special device */
 733         tty_default_fops(&ptmx_fops);
 734         ptmx_fops.open = ptmx_open;
 735
 736         cdev_init(&ptmx_cdev, &ptmx_fops);
 737         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 738             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 739                 panic("Couldn't register /dev/ptmx driver\n");
 740         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 741 }
 742
 743 #else
 744 static inline void unix98_pty_init(void) { }
 745 #endif
 746
 747 static int __init pty_init(void)
 748 {
 749         legacy_pty_init();
 750         unix98_pty_init();
 751         return 0;
 752 }
 753 module_init(pty_init);