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/sysctl.h>
  26 #include <linux/device.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/bitops.h>
  29 #include <linux/devpts_fs.h>
  30
  31 #include <asm/system.h>
  32
  33 #ifdef CONFIG_UNIX98_PTYS
  34 static struct tty_driver *ptm_driver;
  35 static struct tty_driver *pts_driver;
  36 #endif
  37
  38 static void pty_close(struct tty_struct *tty, struct file *filp)
  39 {
  40         BUG_ON(!tty);
  41         if (tty->driver->subtype == PTY_TYPE_MASTER)
  42                 WARN_ON(tty->count > 1);
  43         else {
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         wake_up_interruptible(&tty->read_wait);
  48         wake_up_interruptible(&tty->write_wait);
  49         tty->packet = 0;
  50         if (!tty->link)
  51                 return;
  52         tty->link->packet = 0;
  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                         devpts_pty_kill(tty->link);
  61 #endif
  62                 tty_vhangup(tty->link);
  63         }
  64 }
  65
  66 /*
  67  * The unthrottle routine is called by the line discipline to signal
  68  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  69  * flag is always set, to force the line discipline to always call the
  70  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  71  * characters in the queue.  This is necessary since each time this
  72  * happens, we need to wake up any sleeping processes that could be
  73  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  74  * for the pty buffer to be drained.
  75  */
  76 static void pty_unthrottle(struct tty_struct *tty)
  77 {
  78         struct tty_struct *o_tty = tty->link;
  79
  80         if (!o_tty)
  81                 return;
  82
  83         tty_wakeup(o_tty);
  84         set_bit(TTY_THROTTLED, &tty->flags);
  85 }
  86
  87 /*
  88  * WSH 05/24/97: modified to
  89  *   (1) use space in tty->flip instead of a shared temp buffer
  90  *       The flip buffers aren't being used for a pty, so there's lots
  91  *       of space available.  The buffer is protected by a per-pty
  92  *       semaphore that should almost never come under contention.
  93  *   (2) avoid redundant copying for cases where count >> receive_room
  94  * N.B. Calls from user space may now return an error code instead of
  95  * a count.
  96  *
  97  * FIXME: Our pty_write method is called with our ldisc lock held but
  98  * not our partners. We can't just take the other one blindly without
  99  * risking deadlocks.
 100  */
 101 static int pty_write(struct tty_struct *tty, const unsigned char *buf,
 102                                                                 int count)
 103 {
 104         struct tty_struct *to = tty->link;
 105         int     c;
 106
 107         if (!to || tty->stopped)
 108                 return 0;
 109
 110         c = to->receive_room;
 111         if (c > count)
 112                 c = count;
 113         to->ldisc->ops->receive_buf(to, buf, NULL, c);
 114
 115         return c;
 116 }
 117
 118 static int pty_write_room(struct tty_struct *tty)
 119 {
 120         struct tty_struct *to = tty->link;
 121
 122         if (!to || tty->stopped)
 123                 return 0;
 124
 125         return to->receive_room;
 126 }
 127
 128 /*
 129  *      WSH 05/24/97:  Modified for asymmetric MASTER/SLAVE behavior
 130  *      The chars_in_buffer() value is used by the ldisc select() function
 131  *      to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
 132  *      The pty driver chars_in_buffer() Master/Slave must behave differently:
 133  *
 134  *      The Master side needs to allow typed-ahead commands to accumulate
 135  *      while being canonicalized, so we report "our buffer" as empty until
 136  *      some threshold is reached, and then report the count. (Any count >
 137  *      WAKEUP_CHARS is regarded by select() as "full".)  To avoid deadlock
 138  *      the count returned must be 0 if no canonical data is available to be
 139  *      read. (The N_TTY ldisc.chars_in_buffer now knows this.)
 140  *
 141  *      The Slave side passes all characters in raw mode to the Master side's
 142  *      buffer where they can be read immediately, so in this case we can
 143  *      return the true count in the buffer.
 144  */
 145 static int pty_chars_in_buffer(struct tty_struct *tty)
 146 {
 147         struct tty_struct *to = tty->link;
 148         int count;
 149
 150         /* We should get the line discipline lock for "tty->link" */
 151         if (!to || !to->ldisc->ops->chars_in_buffer)
 152                 return 0;
 153
 154         /* The ldisc must report 0 if no characters available to be read */
 155         count = to->ldisc->ops->chars_in_buffer(to);
 156
 157         if (tty->driver->subtype == PTY_TYPE_SLAVE)
 158                 return count;
 159
 160         /* Master side driver ... if the other side's read buffer is less than
 161          * half full, return 0 to allow writers to proceed; otherwise return
 162          * the count.  This leaves a comfortable margin to avoid overflow,
 163          * and still allows half a buffer's worth of typed-ahead commands.
 164          */
 165         return (count < N_TTY_BUF_SIZE/2) ? 0 : count;
 166 }
 167
 168 /* Set the lock flag on a pty */
 169 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 170 {
 171         int val;
 172         if (get_user(val, arg))
 173                 return -EFAULT;
 174         if (val)
 175                 set_bit(TTY_PTY_LOCK, &tty->flags);
 176         else
 177                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 178         return 0;
 179 }
 180
 181 static void pty_flush_buffer(struct tty_struct *tty)
 182 {
 183         struct tty_struct *to = tty->link;
 184         unsigned long flags;
 185
 186         if (!to)
 187                 return;
 188
 189         if (to->ldisc->ops->flush_buffer)
 190                 to->ldisc->ops->flush_buffer(to);
 191
 192         if (to->packet) {
 193                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 194                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 195                 wake_up_interruptible(&to->read_wait);
 196                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 197         }
 198 }
 199
 200 static int pty_open(struct tty_struct *tty, struct file *filp)
 201 {
 202         int     retval = -ENODEV;
 203
 204         if (!tty || !tty->link)
 205                 goto out;
 206
 207         retval = -EIO;
 208         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 209                 goto out;
 210         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 211                 goto out;
 212         if (tty->link->count != 1)
 213                 goto out;
 214
 215         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 216         set_bit(TTY_THROTTLED, &tty->flags);
 217         retval = 0;
 218 out:
 219         return retval;
 220 }
 221
 222 static void pty_set_termios(struct tty_struct *tty,
 223                                         struct ktermios *old_termios)
 224 {
 225         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 226         tty->termios->c_cflag |= (CS8 | CREAD);
 227 }
 228
 229 /**
 230  *      pty_do_resize           -       resize event
 231  *      @tty: tty being resized
 232  *      @ws: window size being set.
 233  *
 234  *      Update the termios variables and send the neccessary signals to
 235  *      peform a terminal resize correctly
 236  */
 237
 238 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 239 {
 240         struct pid *pgrp, *rpgrp;
 241         unsigned long flags;
 242         struct tty_struct *pty = tty->link;
 243
 244         /* For a PTY we need to lock the tty side */
 245         mutex_lock(&tty->termios_mutex);
 246         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 247                 goto done;
 248
 249         /* Get the PID values and reference them so we can
 250            avoid holding the tty ctrl lock while sending signals.
 251            We need to lock these individually however. */
 252
 253         spin_lock_irqsave(&tty->ctrl_lock, flags);
 254         pgrp = get_pid(tty->pgrp);
 255         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 256
 257         spin_lock_irqsave(&pty->ctrl_lock, flags);
 258         rpgrp = get_pid(pty->pgrp);
 259         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 260
 261         if (pgrp)
 262                 kill_pgrp(pgrp, SIGWINCH, 1);
 263         if (rpgrp != pgrp && rpgrp)
 264                 kill_pgrp(rpgrp, SIGWINCH, 1);
 265
 266         put_pid(pgrp);
 267         put_pid(rpgrp);
 268
 269         tty->winsize = *ws;
 270         pty->winsize = *ws;     /* Never used so will go away soon */
 271 done:
 272         mutex_unlock(&tty->termios_mutex);
 273         return 0;
 274 }
 275
 276 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 277 {
 278         struct tty_struct *o_tty;
 279         int idx = tty->index;
 280         int retval;
 281
 282         o_tty = alloc_tty_struct();
 283         if (!o_tty)
 284                 return -ENOMEM;
 285         if (!try_module_get(driver->other->owner)) {
 286                 /* This cannot in fact currently happen */
 287                 free_tty_struct(o_tty);
 288                 return -ENOMEM;
 289         }
 290         initialize_tty_struct(o_tty, driver->other, idx);
 291
 292         /* We always use new tty termios data so we can do this
 293            the easy way .. */
 294         retval = tty_init_termios(tty);
 295         if (retval)
 296                 goto free_mem_out;
 297
 298         retval = tty_init_termios(o_tty);
 299         if (retval) {
 300                 tty_free_termios(tty);
 301                 goto free_mem_out;
 302         }
 303
 304         /*
 305          * Everything allocated ... set up the o_tty structure.
 306          */
 307         driver->other->ttys[idx] = o_tty;
 308         tty_driver_kref_get(driver->other);
 309         if (driver->subtype == PTY_TYPE_MASTER)
 310                 o_tty->count++;
 311         /* Establish the links in both directions */
 312         tty->link   = o_tty;
 313         o_tty->link = tty;
 314
 315         tty_driver_kref_get(driver);
 316         tty->count++;
 317         driver->ttys[idx] = tty;
 318         return 0;
 319 free_mem_out:
 320         module_put(o_tty->driver->owner);
 321         free_tty_struct(o_tty);
 322         return -ENOMEM;
 323 }
 324
 325
 326 static const struct tty_operations pty_ops = {
 327         .install = pty_install,
 328         .open = pty_open,
 329         .close = pty_close,
 330         .write = pty_write,
 331         .write_room = pty_write_room,
 332         .flush_buffer = pty_flush_buffer,
 333         .chars_in_buffer = pty_chars_in_buffer,
 334         .unthrottle = pty_unthrottle,
 335         .set_termios = pty_set_termios,
 336         .resize = pty_resize
 337 };
 338
 339 /* Traditional BSD devices */
 340 #ifdef CONFIG_LEGACY_PTYS
 341 static struct tty_driver *pty_driver, *pty_slave_driver;
 342
 343 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 344                          unsigned int cmd, unsigned long arg)
 345 {
 346         switch (cmd) {
 347         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 348                 return pty_set_lock(tty, (int __user *) arg);
 349         }
 350         return -ENOIOCTLCMD;
 351 }
 352
 353 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 354 module_param(legacy_count, int, 0);
 355
 356 static const struct tty_operations pty_ops_bsd = {
 357         .open = pty_open,
 358         .close = pty_close,
 359         .write = pty_write,
 360         .write_room = pty_write_room,
 361         .flush_buffer = pty_flush_buffer,
 362         .chars_in_buffer = pty_chars_in_buffer,
 363         .unthrottle = pty_unthrottle,
 364         .set_termios = pty_set_termios,
 365         .ioctl = pty_bsd_ioctl,
 366         .resize = pty_resize
 367 };
 368
 369 static void __init legacy_pty_init(void)
 370 {
 371         if (legacy_count <= 0)
 372                 return;
 373
 374         pty_driver = alloc_tty_driver(legacy_count);
 375         if (!pty_driver)
 376                 panic("Couldn't allocate pty driver");
 377
 378         pty_slave_driver = alloc_tty_driver(legacy_count);
 379         if (!pty_slave_driver)
 380                 panic("Couldn't allocate pty slave driver");
 381
 382         pty_driver->owner = THIS_MODULE;
 383         pty_driver->driver_name = "pty_master";
 384         pty_driver->name = "pty";
 385         pty_driver->major = PTY_MASTER_MAJOR;
 386         pty_driver->minor_start = 0;
 387         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 388         pty_driver->subtype = PTY_TYPE_MASTER;
 389         pty_driver->init_termios = tty_std_termios;
 390         pty_driver->init_termios.c_iflag = 0;
 391         pty_driver->init_termios.c_oflag = 0;
 392         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 393         pty_driver->init_termios.c_lflag = 0;
 394         pty_driver->init_termios.c_ispeed = 38400;
 395         pty_driver->init_termios.c_ospeed = 38400;
 396         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 397         pty_driver->other = pty_slave_driver;
 398         tty_set_operations(pty_driver, &pty_ops);
 399
 400         pty_slave_driver->owner = THIS_MODULE;
 401         pty_slave_driver->driver_name = "pty_slave";
 402         pty_slave_driver->name = "ttyp";
 403         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 404         pty_slave_driver->minor_start = 0;
 405         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 406         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 407         pty_slave_driver->init_termios = tty_std_termios;
 408         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 409         pty_slave_driver->init_termios.c_ispeed = 38400;
 410         pty_slave_driver->init_termios.c_ospeed = 38400;
 411         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 412                                         TTY_DRIVER_REAL_RAW;
 413         pty_slave_driver->other = pty_driver;
 414         tty_set_operations(pty_slave_driver, &pty_ops);
 415
 416         if (tty_register_driver(pty_driver))
 417                 panic("Couldn't register pty driver");
 418         if (tty_register_driver(pty_slave_driver))
 419                 panic("Couldn't register pty slave driver");
 420 }
 421 #else
 422 static inline void legacy_pty_init(void) { }
 423 #endif
 424
 425 /* Unix98 devices */
 426 #ifdef CONFIG_UNIX98_PTYS
 427 /*
 428  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 429  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 430  */
 431 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 432 static int pty_limit_min;
 433 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 434 static int pty_count;
 435
 436 static struct cdev ptmx_cdev;
 437
 438 static struct ctl_table pty_table[] = {
 439         {
 440                 .ctl_name       = PTY_MAX,
 441                 .procname       = "max",
 442                 .maxlen         = sizeof(int),
 443                 .mode           = 0644,
 444                 .data           = &pty_limit,
 445                 .proc_handler   = &proc_dointvec_minmax,
 446                 .strategy       = &sysctl_intvec,
 447                 .extra1         = &pty_limit_min,
 448                 .extra2         = &pty_limit_max,
 449         }, {
 450                 .ctl_name       = PTY_NR,
 451                 .procname       = "nr",
 452                 .maxlen         = sizeof(int),
 453                 .mode           = 0444,
 454                 .data           = &pty_count,
 455                 .proc_handler   = &proc_dointvec,
 456         }, {
 457                 .ctl_name       = 0
 458         }
 459 };
 460
 461 static struct ctl_table pty_kern_table[] = {
 462         {
 463                 .ctl_name       = KERN_PTY,
 464                 .procname       = "pty",
 465                 .mode           = 0555,
 466                 .child          = pty_table,
 467         },
 468         {}
 469 };
 470
 471 static struct ctl_table pty_root_table[] = {
 472         {
 473                 .ctl_name       = CTL_KERN,
 474                 .procname       = "kernel",
 475                 .mode           = 0555,
 476                 .child          = pty_kern_table,
 477         },
 478         {}
 479 };
 480
 481
 482 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 483                             unsigned int cmd, unsigned long arg)
 484 {
 485         switch (cmd) {
 486         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 487                 return pty_set_lock(tty, (int __user *)arg);
 488         case TIOCGPTN: /* Get PT Number */
 489                 return put_user(tty->index, (unsigned int __user *)arg);
 490         }
 491
 492         return -ENOIOCTLCMD;
 493 }
 494
 495 /**
 496  *      ptm_unix98_lookup       -       find a pty master
 497  *      @driver: ptm driver
 498  *      @idx: tty index
 499  *
 500  *      Look up a pty master device. Called under the tty_mutex for now.
 501  *      This provides our locking.
 502  */
 503
 504 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 505                 struct inode *ptm_inode, int idx)
 506 {
 507         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 508         if (tty)
 509                 tty = tty->link;
 510         return tty;
 511 }
 512
 513 /**
 514  *      pts_unix98_lookup       -       find a pty slave
 515  *      @driver: pts driver
 516  *      @idx: tty index
 517  *
 518  *      Look up a pty master device. Called under the tty_mutex for now.
 519  *      This provides our locking.
 520  */
 521
 522 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 523                 struct inode *pts_inode, int idx)
 524 {
 525         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 526         /* Master must be open before slave */
 527         if (!tty)
 528                 return ERR_PTR(-EIO);
 529         return tty;
 530 }
 531
 532 static void pty_unix98_shutdown(struct tty_struct *tty)
 533 {
 534         /* We have our own method as we don't use the tty index */
 535         kfree(tty->termios);
 536 }
 537
 538 /* We have no need to install and remove our tty objects as devpts does all
 539    the work for us */
 540
 541 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 542 {
 543         struct tty_struct *o_tty;
 544         int idx = tty->index;
 545
 546         o_tty = alloc_tty_struct();
 547         if (!o_tty)
 548                 return -ENOMEM;
 549         if (!try_module_get(driver->other->owner)) {
 550                 /* This cannot in fact currently happen */
 551                 free_tty_struct(o_tty);
 552                 return -ENOMEM;
 553         }
 554         initialize_tty_struct(o_tty, driver->other, idx);
 555
 556         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 557         if (tty->termios == NULL)
 558                 goto free_mem_out;
 559         *tty->termios = driver->init_termios;
 560         tty->termios_locked = tty->termios + 1;
 561
 562         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 563         if (o_tty->termios == NULL)
 564                 goto free_mem_out;
 565         *o_tty->termios = driver->other->init_termios;
 566         o_tty->termios_locked = o_tty->termios + 1;
 567
 568         tty_driver_kref_get(driver->other);
 569         if (driver->subtype == PTY_TYPE_MASTER)
 570                 o_tty->count++;
 571         /* Establish the links in both directions */
 572         tty->link   = o_tty;
 573         o_tty->link = tty;
 574         /*
 575          * All structures have been allocated, so now we install them.
 576          * Failures after this point use release_tty to clean up, so
 577          * there's no need to null out the local pointers.
 578          */
 579         tty_driver_kref_get(driver);
 580         tty->count++;
 581         pty_count++;
 582         return 0;
 583 free_mem_out:
 584         kfree(o_tty->termios);
 585         module_put(o_tty->driver->owner);
 586         free_tty_struct(o_tty);
 587         kfree(tty->termios);
 588         return -ENOMEM;
 589 }
 590
 591 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 592 {
 593         pty_count--;
 594 }
 595
 596 static const struct tty_operations ptm_unix98_ops = {
 597         .lookup = ptm_unix98_lookup,
 598         .install = pty_unix98_install,
 599         .remove = pty_unix98_remove,
 600         .open = pty_open,
 601         .close = pty_close,
 602         .write = pty_write,
 603         .write_room = pty_write_room,
 604         .flush_buffer = pty_flush_buffer,
 605         .chars_in_buffer = pty_chars_in_buffer,
 606         .unthrottle = pty_unthrottle,
 607         .set_termios = pty_set_termios,
 608         .ioctl = pty_unix98_ioctl,
 609         .shutdown = pty_unix98_shutdown,
 610         .resize = pty_resize
 611 };
 612
 613 static const struct tty_operations pty_unix98_ops = {
 614         .lookup = pts_unix98_lookup,
 615         .install = pty_unix98_install,
 616         .remove = pty_unix98_remove,
 617         .open = pty_open,
 618         .close = pty_close,
 619         .write = pty_write,
 620         .write_room = pty_write_room,
 621         .flush_buffer = pty_flush_buffer,
 622         .chars_in_buffer = pty_chars_in_buffer,
 623         .unthrottle = pty_unthrottle,
 624         .set_termios = pty_set_termios,
 625         .shutdown = pty_unix98_shutdown
 626 };
 627
 628 /**
 629  *      ptmx_open               -       open a unix 98 pty master
 630  *      @inode: inode of device file
 631  *      @filp: file pointer to tty
 632  *
 633  *      Allocate a unix98 pty master device from the ptmx driver.
 634  *
 635  *      Locking: tty_mutex protects the init_dev work. tty->count should
 636  *              protect the rest.
 637  *              allocated_ptys_lock handles the list of free pty numbers
 638  */
 639
 640 static int __ptmx_open(struct inode *inode, struct file *filp)
 641 {
 642         struct tty_struct *tty;
 643         int retval;
 644         int index;
 645
 646         nonseekable_open(inode, filp);
 647
 648         /* find a device that is not in use. */
 649         index = devpts_new_index(inode);
 650         if (index < 0)
 651                 return index;
 652
 653         mutex_lock(&tty_mutex);
 654         tty = tty_init_dev(ptm_driver, index, 1);
 655         mutex_unlock(&tty_mutex);
 656
 657         if (IS_ERR(tty)) {
 658                 retval = PTR_ERR(tty);
 659                 goto out;
 660         }
 661
 662         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 663         filp->private_data = tty;
 664         file_move(filp, &tty->tty_files);
 665
 666         retval = devpts_pty_new(inode, tty->link);
 667         if (retval)
 668                 goto out1;
 669
 670         retval = ptm_driver->ops->open(tty, filp);
 671         if (!retval)
 672                 return 0;
 673 out1:
 674         tty_release_dev(filp);
 675         return retval;
 676 out:
 677         devpts_kill_index(inode, index);
 678         return retval;
 679 }
 680
 681 static int ptmx_open(struct inode *inode, struct file *filp)
 682 {
 683         int ret;
 684
 685         lock_kernel();
 686         ret = __ptmx_open(inode, filp);
 687         unlock_kernel();
 688         return ret;
 689 }
 690
 691 static struct file_operations ptmx_fops;
 692
 693 static void __init unix98_pty_init(void)
 694 {
 695         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 696         if (!ptm_driver)
 697                 panic("Couldn't allocate Unix98 ptm driver");
 698         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 699         if (!pts_driver)
 700                 panic("Couldn't allocate Unix98 pts driver");
 701
 702         ptm_driver->owner = THIS_MODULE;
 703         ptm_driver->driver_name = "pty_master";
 704         ptm_driver->name = "ptm";
 705         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 706         ptm_driver->minor_start = 0;
 707         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 708         ptm_driver->subtype = PTY_TYPE_MASTER;
 709         ptm_driver->init_termios = tty_std_termios;
 710         ptm_driver->init_termios.c_iflag = 0;
 711         ptm_driver->init_termios.c_oflag = 0;
 712         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 713         ptm_driver->init_termios.c_lflag = 0;
 714         ptm_driver->init_termios.c_ispeed = 38400;
 715         ptm_driver->init_termios.c_ospeed = 38400;
 716         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 717                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 718         ptm_driver->other = pts_driver;
 719         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 720
 721         pts_driver->owner = THIS_MODULE;
 722         pts_driver->driver_name = "pty_slave";
 723         pts_driver->name = "pts";
 724         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 725         pts_driver->minor_start = 0;
 726         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 727         pts_driver->subtype = PTY_TYPE_SLAVE;
 728         pts_driver->init_termios = tty_std_termios;
 729         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 730         pts_driver->init_termios.c_ispeed = 38400;
 731         pts_driver->init_termios.c_ospeed = 38400;
 732         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 733                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 734         pts_driver->other = ptm_driver;
 735         tty_set_operations(pts_driver, &pty_unix98_ops);
 736
 737         if (tty_register_driver(ptm_driver))
 738                 panic("Couldn't register Unix98 ptm driver");
 739         if (tty_register_driver(pts_driver))
 740                 panic("Couldn't register Unix98 pts driver");
 741
 742         register_sysctl_table(pty_root_table);
 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);