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/string.h>
  22 #include <linux/major.h>
  23 #include <linux/mm.h>
  24 #include <linux/init.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/sysctl.h>
  27 #include <linux/device.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/bitops.h>
  30 #include <linux/devpts_fs.h>
  31
  32 #include <asm/system.h>
  33
  34 #ifdef CONFIG_UNIX98_PTYS
  35 static struct tty_driver *ptm_driver;
  36 static struct tty_driver *pts_driver;
  37 #endif
  38
  39 static void pty_close(struct tty_struct *tty, struct file *filp)
  40 {
  41         BUG_ON(!tty);
  42         if (tty->driver->subtype == PTY_TYPE_MASTER)
  43                 WARN_ON(tty->count > 1);
  44         else {
  45                 if (tty->count > 2)
  46                         return;
  47         }
  48         wake_up_interruptible(&tty->read_wait);
  49         wake_up_interruptible(&tty->write_wait);
  50         tty->packet = 0;
  51         if (!tty->link)
  52                 return;
  53         tty->link->packet = 0;
  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                         devpts_pty_kill(tty->link);
  62 #endif
  63                 tty_vhangup(tty->link);
  64         }
  65 }
  66
  67 /*
  68  * The unthrottle routine is called by the line discipline to signal
  69  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  70  * flag is always set, to force the line discipline to always call the
  71  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  72  * characters in the queue.  This is necessary since each time this
  73  * happens, we need to wake up any sleeping processes that could be
  74  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  75  * for the pty buffer to be drained.
  76  */
  77 static void pty_unthrottle(struct tty_struct *tty)
  78 {
  79         tty_wakeup(tty->link);
  80         set_bit(TTY_THROTTLED, &tty->flags);
  81 }
  82
  83 /**
  84  *      pty_space       -       report space left for writing
  85  *      @to: tty we are writing into
  86  *
  87  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  88  *      allows a lot of overspill room for echo and other fun messes to
  89  *      be handled properly
  90  */
  91
  92 static int pty_space(struct tty_struct *to)
  93 {
  94         int n = 8192 - to->buf.memory_used;
  95         if (n < 0)
  96                 return 0;
  97         return n;
  98 }
  99
 100 /**
 101  *      pty_write               -       write to a pty
 102  *      @tty: the tty we write from
 103  *      @buf: kernel buffer of data
 104  *      @count: bytes to write
 105  *
 106  *      Our "hardware" write method. Data is coming from the ldisc which
 107  *      may be in a non sleeping state. We simply throw this at the other
 108  *      end of the link as if we were an IRQ handler receiving stuff for
 109  *      the other side of the pty/tty pair.
 110  */
 111
 112 static int pty_write(struct tty_struct *tty, const unsigned char *buf,
 113                                                                 int count)
 114 {
 115         struct tty_struct *to = tty->link;
 116         int c;
 117
 118         if (tty->stopped)
 119                 return 0;
 120
 121         /* This isn't locked but our 8K is quite sloppy so no
 122            big deal */
 123
 124         c = pty_space(to);
 125         if (c > count)
 126                 c = count;
 127         if (c > 0) {
 128                 /* Stuff the data into the input queue of the other end */
 129                 c = tty_insert_flip_string(to, buf, c);
 130                 /* And shovel */
 131                 tty_flip_buffer_push(to);
 132                 tty_wakeup(tty);
 133         }
 134         return c;
 135 }
 136
 137 /**
 138  *      pty_write_room  -       write space
 139  *      @tty: tty we are writing from
 140  *
 141  *      Report how many bytes the ldisc can send into the queue for
 142  *      the other device.
 143  */
 144
 145 static int pty_write_room(struct tty_struct *tty)
 146 {
 147         return pty_space(tty->link);
 148 }
 149
 150 /**
 151  *      pty_chars_in_buffer     -       characters currently in our tx queue
 152  *      @tty: our tty
 153  *
 154  *      Report how much we have in the transmit queue. As everything is
 155  *      instantly at the other end this is easy to implement.
 156  */
 157
 158 static int pty_chars_in_buffer(struct tty_struct *tty)
 159 {
 160         return 0;
 161 }
 162
 163 /* Set the lock flag on a pty */
 164 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 165 {
 166         int val;
 167         if (get_user(val, arg))
 168                 return -EFAULT;
 169         if (val)
 170                 set_bit(TTY_PTY_LOCK, &tty->flags);
 171         else
 172                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 173         return 0;
 174 }
 175
 176 static void pty_flush_buffer(struct tty_struct *tty)
 177 {
 178         struct tty_struct *to = tty->link;
 179         unsigned long flags;
 180
 181         if (!to)
 182                 return;
 183         /* tty_buffer_flush(to); FIXME */
 184         if (to->packet) {
 185                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 186                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 187                 wake_up_interruptible(&to->read_wait);
 188                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 189         }
 190 }
 191
 192 static int pty_open(struct tty_struct *tty, struct file *filp)
 193 {
 194         int     retval = -ENODEV;
 195
 196         if (!tty || !tty->link)
 197                 goto out;
 198
 199         retval = -EIO;
 200         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 201                 goto out;
 202         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 203                 goto out;
 204         if (tty->link->count != 1)
 205                 goto out;
 206
 207         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 208         set_bit(TTY_THROTTLED, &tty->flags);
 209         retval = 0;
 210 out:
 211         return retval;
 212 }
 213
 214 static void pty_set_termios(struct tty_struct *tty,
 215                                         struct ktermios *old_termios)
 216 {
 217         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 218         tty->termios->c_cflag |= (CS8 | CREAD);
 219 }
 220
 221 /**
 222  *      pty_do_resize           -       resize event
 223  *      @tty: tty being resized
 224  *      @ws: window size being set.
 225  *
 226  *      Update the termios variables and send the neccessary signals to
 227  *      peform a terminal resize correctly
 228  */
 229
 230 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 231 {
 232         struct pid *pgrp, *rpgrp;
 233         unsigned long flags;
 234         struct tty_struct *pty = tty->link;
 235
 236         /* For a PTY we need to lock the tty side */
 237         mutex_lock(&tty->termios_mutex);
 238         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 239                 goto done;
 240
 241         /* Get the PID values and reference them so we can
 242            avoid holding the tty ctrl lock while sending signals.
 243            We need to lock these individually however. */
 244
 245         spin_lock_irqsave(&tty->ctrl_lock, flags);
 246         pgrp = get_pid(tty->pgrp);
 247         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 248
 249         spin_lock_irqsave(&pty->ctrl_lock, flags);
 250         rpgrp = get_pid(pty->pgrp);
 251         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 252
 253         if (pgrp)
 254                 kill_pgrp(pgrp, SIGWINCH, 1);
 255         if (rpgrp != pgrp && rpgrp)
 256                 kill_pgrp(rpgrp, SIGWINCH, 1);
 257
 258         put_pid(pgrp);
 259         put_pid(rpgrp);
 260
 261         tty->winsize = *ws;
 262         pty->winsize = *ws;     /* Never used so will go away soon */
 263 done:
 264         mutex_unlock(&tty->termios_mutex);
 265         return 0;
 266 }
 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
 318 static const struct tty_operations pty_ops = {
 319         .install = pty_install,
 320         .open = pty_open,
 321         .close = pty_close,
 322         .write = pty_write,
 323         .write_room = pty_write_room,
 324         .flush_buffer = pty_flush_buffer,
 325         .chars_in_buffer = pty_chars_in_buffer,
 326         .unthrottle = pty_unthrottle,
 327         .set_termios = pty_set_termios,
 328         .resize = pty_resize
 329 };
 330
 331 /* Traditional BSD devices */
 332 #ifdef CONFIG_LEGACY_PTYS
 333 static struct tty_driver *pty_driver, *pty_slave_driver;
 334
 335 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 336                          unsigned int cmd, unsigned long arg)
 337 {
 338         switch (cmd) {
 339         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 340                 return pty_set_lock(tty, (int __user *) arg);
 341         }
 342         return -ENOIOCTLCMD;
 343 }
 344
 345 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 346 module_param(legacy_count, int, 0);
 347
 348 static const struct tty_operations pty_ops_bsd = {
 349         .open = pty_open,
 350         .close = pty_close,
 351         .write = pty_write,
 352         .write_room = pty_write_room,
 353         .flush_buffer = pty_flush_buffer,
 354         .chars_in_buffer = pty_chars_in_buffer,
 355         .unthrottle = pty_unthrottle,
 356         .set_termios = pty_set_termios,
 357         .ioctl = pty_bsd_ioctl,
 358         .resize = pty_resize
 359 };
 360
 361 static void __init legacy_pty_init(void)
 362 {
 363         if (legacy_count <= 0)
 364                 return;
 365
 366         pty_driver = alloc_tty_driver(legacy_count);
 367         if (!pty_driver)
 368                 panic("Couldn't allocate pty driver");
 369
 370         pty_slave_driver = alloc_tty_driver(legacy_count);
 371         if (!pty_slave_driver)
 372                 panic("Couldn't allocate pty slave driver");
 373
 374         pty_driver->owner = THIS_MODULE;
 375         pty_driver->driver_name = "pty_master";
 376         pty_driver->name = "pty";
 377         pty_driver->major = PTY_MASTER_MAJOR;
 378         pty_driver->minor_start = 0;
 379         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 380         pty_driver->subtype = PTY_TYPE_MASTER;
 381         pty_driver->init_termios = tty_std_termios;
 382         pty_driver->init_termios.c_iflag = 0;
 383         pty_driver->init_termios.c_oflag = 0;
 384         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 385         pty_driver->init_termios.c_lflag = 0;
 386         pty_driver->init_termios.c_ispeed = 38400;
 387         pty_driver->init_termios.c_ospeed = 38400;
 388         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 389         pty_driver->other = pty_slave_driver;
 390         tty_set_operations(pty_driver, &pty_ops);
 391
 392         pty_slave_driver->owner = THIS_MODULE;
 393         pty_slave_driver->driver_name = "pty_slave";
 394         pty_slave_driver->name = "ttyp";
 395         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 396         pty_slave_driver->minor_start = 0;
 397         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 398         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 399         pty_slave_driver->init_termios = tty_std_termios;
 400         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 401         pty_slave_driver->init_termios.c_ispeed = 38400;
 402         pty_slave_driver->init_termios.c_ospeed = 38400;
 403         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 404                                         TTY_DRIVER_REAL_RAW;
 405         pty_slave_driver->other = pty_driver;
 406         tty_set_operations(pty_slave_driver, &pty_ops);
 407
 408         if (tty_register_driver(pty_driver))
 409                 panic("Couldn't register pty driver");
 410         if (tty_register_driver(pty_slave_driver))
 411                 panic("Couldn't register pty slave driver");
 412 }
 413 #else
 414 static inline void legacy_pty_init(void) { }
 415 #endif
 416
 417 /* Unix98 devices */
 418 #ifdef CONFIG_UNIX98_PTYS
 419 /*
 420  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 421  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 422  */
 423 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 424 static int pty_limit_min;
 425 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 426 static int pty_count;
 427
 428 static struct cdev ptmx_cdev;
 429
 430 static struct ctl_table pty_table[] = {
 431         {
 432                 .ctl_name       = PTY_MAX,
 433                 .procname       = "max",
 434                 .maxlen         = sizeof(int),
 435                 .mode           = 0644,
 436                 .data           = &pty_limit,
 437                 .proc_handler   = &proc_dointvec_minmax,
 438                 .strategy       = &sysctl_intvec,
 439                 .extra1         = &pty_limit_min,
 440                 .extra2         = &pty_limit_max,
 441         }, {
 442                 .ctl_name       = PTY_NR,
 443                 .procname       = "nr",
 444                 .maxlen         = sizeof(int),
 445                 .mode           = 0444,
 446                 .data           = &pty_count,
 447                 .proc_handler   = &proc_dointvec,
 448         }, {
 449                 .ctl_name       = 0
 450         }
 451 };
 452
 453 static struct ctl_table pty_kern_table[] = {
 454         {
 455                 .ctl_name       = KERN_PTY,
 456                 .procname       = "pty",
 457                 .mode           = 0555,
 458                 .child          = pty_table,
 459         },
 460         {}
 461 };
 462
 463 static struct ctl_table pty_root_table[] = {
 464         {
 465                 .ctl_name       = CTL_KERN,
 466                 .procname       = "kernel",
 467                 .mode           = 0555,
 468                 .child          = pty_kern_table,
 469         },
 470         {}
 471 };
 472
 473
 474 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 475                             unsigned int cmd, unsigned long arg)
 476 {
 477         switch (cmd) {
 478         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 479                 return pty_set_lock(tty, (int __user *)arg);
 480         case TIOCGPTN: /* Get PT Number */
 481                 return put_user(tty->index, (unsigned int __user *)arg);
 482         }
 483
 484         return -ENOIOCTLCMD;
 485 }
 486
 487 /**
 488  *      ptm_unix98_lookup       -       find a pty master
 489  *      @driver: ptm driver
 490  *      @idx: tty index
 491  *
 492  *      Look up a pty master device. Called under the tty_mutex for now.
 493  *      This provides our locking.
 494  */
 495
 496 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 497                 struct inode *ptm_inode, int idx)
 498 {
 499         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 500         if (tty)
 501                 tty = tty->link;
 502         return tty;
 503 }
 504
 505 /**
 506  *      pts_unix98_lookup       -       find a pty slave
 507  *      @driver: pts driver
 508  *      @idx: tty index
 509  *
 510  *      Look up a pty master device. Called under the tty_mutex for now.
 511  *      This provides our locking.
 512  */
 513
 514 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 515                 struct inode *pts_inode, int idx)
 516 {
 517         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 518         /* Master must be open before slave */
 519         if (!tty)
 520                 return ERR_PTR(-EIO);
 521         return tty;
 522 }
 523
 524 static void pty_unix98_shutdown(struct tty_struct *tty)
 525 {
 526         /* We have our own method as we don't use the tty index */
 527         kfree(tty->termios);
 528 }
 529
 530 /* We have no need to install and remove our tty objects as devpts does all
 531    the work for us */
 532
 533 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 534 {
 535         struct tty_struct *o_tty;
 536         int idx = tty->index;
 537
 538         o_tty = alloc_tty_struct();
 539         if (!o_tty)
 540                 return -ENOMEM;
 541         if (!try_module_get(driver->other->owner)) {
 542                 /* This cannot in fact currently happen */
 543                 free_tty_struct(o_tty);
 544                 return -ENOMEM;
 545         }
 546         initialize_tty_struct(o_tty, driver->other, idx);
 547
 548         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 549         if (tty->termios == NULL)
 550                 goto free_mem_out;
 551         *tty->termios = driver->init_termios;
 552         tty->termios_locked = tty->termios + 1;
 553
 554         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 555         if (o_tty->termios == NULL)
 556                 goto free_mem_out;
 557         *o_tty->termios = driver->other->init_termios;
 558         o_tty->termios_locked = o_tty->termios + 1;
 559
 560         tty_driver_kref_get(driver->other);
 561         if (driver->subtype == PTY_TYPE_MASTER)
 562                 o_tty->count++;
 563         /* Establish the links in both directions */
 564         tty->link   = o_tty;
 565         o_tty->link = tty;
 566         /*
 567          * All structures have been allocated, so now we install them.
 568          * Failures after this point use release_tty to clean up, so
 569          * there's no need to null out the local pointers.
 570          */
 571         tty_driver_kref_get(driver);
 572         tty->count++;
 573         pty_count++;
 574         return 0;
 575 free_mem_out:
 576         kfree(o_tty->termios);
 577         module_put(o_tty->driver->owner);
 578         free_tty_struct(o_tty);
 579         kfree(tty->termios);
 580         return -ENOMEM;
 581 }
 582
 583 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 584 {
 585         pty_count--;
 586 }
 587
 588 static const struct tty_operations ptm_unix98_ops = {
 589         .lookup = ptm_unix98_lookup,
 590         .install = pty_unix98_install,
 591         .remove = pty_unix98_remove,
 592         .open = pty_open,
 593         .close = pty_close,
 594         .write = pty_write,
 595         .write_room = pty_write_room,
 596         .flush_buffer = pty_flush_buffer,
 597         .chars_in_buffer = pty_chars_in_buffer,
 598         .unthrottle = pty_unthrottle,
 599         .set_termios = pty_set_termios,
 600         .ioctl = pty_unix98_ioctl,
 601         .shutdown = pty_unix98_shutdown,
 602         .resize = pty_resize
 603 };
 604
 605 static const struct tty_operations pty_unix98_ops = {
 606         .lookup = pts_unix98_lookup,
 607         .install = pty_unix98_install,
 608         .remove = pty_unix98_remove,
 609         .open = pty_open,
 610         .close = pty_close,
 611         .write = pty_write,
 612         .write_room = pty_write_room,
 613         .flush_buffer = pty_flush_buffer,
 614         .chars_in_buffer = pty_chars_in_buffer,
 615         .unthrottle = pty_unthrottle,
 616         .set_termios = pty_set_termios,
 617         .shutdown = pty_unix98_shutdown
 618 };
 619
 620 /**
 621  *      ptmx_open               -       open a unix 98 pty master
 622  *      @inode: inode of device file
 623  *      @filp: file pointer to tty
 624  *
 625  *      Allocate a unix98 pty master device from the ptmx driver.
 626  *
 627  *      Locking: tty_mutex protects the init_dev work. tty->count should
 628  *              protect the rest.
 629  *              allocated_ptys_lock handles the list of free pty numbers
 630  */
 631
 632 static int __ptmx_open(struct inode *inode, struct file *filp)
 633 {
 634         struct tty_struct *tty;
 635         int retval;
 636         int index;
 637
 638         nonseekable_open(inode, filp);
 639
 640         /* find a device that is not in use. */
 641         index = devpts_new_index(inode);
 642         if (index < 0)
 643                 return index;
 644
 645         mutex_lock(&tty_mutex);
 646         tty = tty_init_dev(ptm_driver, index, 1);
 647         mutex_unlock(&tty_mutex);
 648
 649         if (IS_ERR(tty)) {
 650                 retval = PTR_ERR(tty);
 651                 goto out;
 652         }
 653
 654         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 655         filp->private_data = tty;
 656         file_move(filp, &tty->tty_files);
 657
 658         retval = devpts_pty_new(inode, tty->link);
 659         if (retval)
 660                 goto out1;
 661
 662         retval = ptm_driver->ops->open(tty, filp);
 663         if (!retval)
 664                 return 0;
 665 out1:
 666         tty_release_dev(filp);
 667         return retval;
 668 out:
 669         devpts_kill_index(inode, index);
 670         return retval;
 671 }
 672
 673 static int ptmx_open(struct inode *inode, struct file *filp)
 674 {
 675         int ret;
 676
 677         lock_kernel();
 678         ret = __ptmx_open(inode, filp);
 679         unlock_kernel();
 680         return ret;
 681 }
 682
 683 static struct file_operations ptmx_fops;
 684
 685 static void __init unix98_pty_init(void)
 686 {
 687         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 688         if (!ptm_driver)
 689                 panic("Couldn't allocate Unix98 ptm driver");
 690         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 691         if (!pts_driver)
 692                 panic("Couldn't allocate Unix98 pts driver");
 693
 694         ptm_driver->owner = THIS_MODULE;
 695         ptm_driver->driver_name = "pty_master";
 696         ptm_driver->name = "ptm";
 697         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 698         ptm_driver->minor_start = 0;
 699         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 700         ptm_driver->subtype = PTY_TYPE_MASTER;
 701         ptm_driver->init_termios = tty_std_termios;
 702         ptm_driver->init_termios.c_iflag = 0;
 703         ptm_driver->init_termios.c_oflag = 0;
 704         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 705         ptm_driver->init_termios.c_lflag = 0;
 706         ptm_driver->init_termios.c_ispeed = 38400;
 707         ptm_driver->init_termios.c_ospeed = 38400;
 708         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 709                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 710         ptm_driver->other = pts_driver;
 711         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 712
 713         pts_driver->owner = THIS_MODULE;
 714         pts_driver->driver_name = "pty_slave";
 715         pts_driver->name = "pts";
 716         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 717         pts_driver->minor_start = 0;
 718         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 719         pts_driver->subtype = PTY_TYPE_SLAVE;
 720         pts_driver->init_termios = tty_std_termios;
 721         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 722         pts_driver->init_termios.c_ispeed = 38400;
 723         pts_driver->init_termios.c_ospeed = 38400;
 724         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 725                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 726         pts_driver->other = ptm_driver;
 727         tty_set_operations(pts_driver, &pty_unix98_ops);
 728
 729         if (tty_register_driver(ptm_driver))
 730                 panic("Couldn't register Unix98 ptm driver");
 731         if (tty_register_driver(pts_driver))
 732                 panic("Couldn't register Unix98 pts driver");
 733
 734         register_sysctl_table(pty_root_table);
 735
 736         /* Now create the /dev/ptmx special device */
 737         tty_default_fops(&ptmx_fops);
 738         ptmx_fops.open = ptmx_open;
 739
 740         cdev_init(&ptmx_cdev, &ptmx_fops);
 741         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 742             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 743                 panic("Couldn't register /dev/ptmx driver\n");
 744         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 745 }
 746
 747 #else
 748 static inline void unix98_pty_init(void) { }
 749 #endif
 750
 751 static int __init pty_init(void)
 752 {
 753         legacy_pty_init();
 754         unix98_pty_init();
 755         return 0;
 756 }
 757 module_init(pty_init);