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  *  Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
   9  *      waiting writers -- Sapan Bhatia <sapan@corewars.org>
  10  *
  11  *  When reading this code see also fs/devpts. In particular note that the
  12  *  driver_data field is used by the devpts side as a binding to the devpts
  13  *  inode.
  14  */
  15
  16 #include <linux/module.h>
  17
  18 #include <linux/errno.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/tty.h>
  21 #include <linux/tty_flip.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/string.h>
  24 #include <linux/major.h>
  25 #include <linux/mm.h>
  26 #include <linux/init.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 /* These are global because they are accessed in tty_io.c */
  36 #ifdef CONFIG_UNIX98_PTYS
  37 struct tty_driver *ptm_driver;
  38 static struct tty_driver *pts_driver;
  39 #endif
  40
  41 static void pty_close(struct tty_struct *tty, struct file *filp)
  42 {
  43         BUG_ON(!tty);
  44         if (tty->driver->subtype == PTY_TYPE_MASTER)
  45                 WARN_ON(tty->count > 1);
  46         else {
  47                 if (tty->count > 2)
  48                         return;
  49         }
  50         wake_up_interruptible(&tty->read_wait);
  51         wake_up_interruptible(&tty->write_wait);
  52         tty->packet = 0;
  53         if (!tty->link)
  54                 return;
  55         tty->link->packet = 0;
  56         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  57         wake_up_interruptible(&tty->link->read_wait);
  58         wake_up_interruptible(&tty->link->write_wait);
  59         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  60                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  61 #ifdef CONFIG_UNIX98_PTYS
  62                 if (tty->driver == ptm_driver)
  63                         devpts_pty_kill(tty->link);
  64 #endif
  65                 tty_vhangup(tty->link);
  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         struct tty_struct *o_tty = tty->link;
  82
  83         if (!o_tty)
  84                 return;
  85
  86         tty_wakeup(o_tty);
  87         set_bit(TTY_THROTTLED, &tty->flags);
  88 }
  89
  90 /*
  91  * WSH 05/24/97: modified to
  92  *   (1) use space in tty->flip instead of a shared temp buffer
  93  *       The flip buffers aren't being used for a pty, so there's lots
  94  *       of space available.  The buffer is protected by a per-pty
  95  *       semaphore that should almost never come under contention.
  96  *   (2) avoid redundant copying for cases where count >> receive_room
  97  * N.B. Calls from user space may now return an error code instead of
  98  * a count.
  99  *
 100  * FIXME: Our pty_write method is called with our ldisc lock held but
 101  * not our partners. We can't just take the other one blindly without
 102  * risking deadlocks.
 103  */
 104 static int pty_write(struct tty_struct *tty, const unsigned char *buf,
 105                                                                 int count)
 106 {
 107         struct tty_struct *to = tty->link;
 108         int     c;
 109
 110         if (!to || tty->stopped)
 111                 return 0;
 112
 113         c = to->receive_room;
 114         if (c > count)
 115                 c = count;
 116         to->ldisc.ops->receive_buf(to, buf, NULL, c);
 117
 118         return c;
 119 }
 120
 121 static int pty_write_room(struct tty_struct *tty)
 122 {
 123         struct tty_struct *to = tty->link;
 124
 125         if (!to || tty->stopped)
 126                 return 0;
 127
 128         return to->receive_room;
 129 }
 130
 131 /*
 132  *      WSH 05/24/97:  Modified for asymmetric MASTER/SLAVE behavior
 133  *      The chars_in_buffer() value is used by the ldisc select() function
 134  *      to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
 135  *      The pty driver chars_in_buffer() Master/Slave must behave differently:
 136  *
 137  *      The Master side needs to allow typed-ahead commands to accumulate
 138  *      while being canonicalized, so we report "our buffer" as empty until
 139  *      some threshold is reached, and then report the count. (Any count >
 140  *      WAKEUP_CHARS is regarded by select() as "full".)  To avoid deadlock
 141  *      the count returned must be 0 if no canonical data is available to be
 142  *      read. (The N_TTY ldisc.chars_in_buffer now knows this.)
 143  *
 144  *      The Slave side passes all characters in raw mode to the Master side's
 145  *      buffer where they can be read immediately, so in this case we can
 146  *      return the true count in the buffer.
 147  */
 148 static int pty_chars_in_buffer(struct tty_struct *tty)
 149 {
 150         struct tty_struct *to = tty->link;
 151         int count;
 152
 153         /* We should get the line discipline lock for "tty->link" */
 154         if (!to || !to->ldisc.ops->chars_in_buffer)
 155                 return 0;
 156
 157         /* The ldisc must report 0 if no characters available to be read */
 158         count = to->ldisc.ops->chars_in_buffer(to);
 159
 160         if (tty->driver->subtype == PTY_TYPE_SLAVE)
 161                 return count;
 162
 163         /* Master side driver ... if the other side's read buffer is less than
 164          * half full, return 0 to allow writers to proceed; otherwise return
 165          * the count.  This leaves a comfortable margin to avoid overflow,
 166          * and still allows half a buffer's worth of typed-ahead commands.
 167          */
 168         return (count < N_TTY_BUF_SIZE/2) ? 0 : count;
 169 }
 170
 171 /* Set the lock flag on a pty */
 172 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 173 {
 174         int val;
 175         if (get_user(val, arg))
 176                 return -EFAULT;
 177         if (val)
 178                 set_bit(TTY_PTY_LOCK, &tty->flags);
 179         else
 180                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 181         return 0;
 182 }
 183
 184 static void pty_flush_buffer(struct tty_struct *tty)
 185 {
 186         struct tty_struct *to = tty->link;
 187         unsigned long flags;
 188
 189         if (!to)
 190                 return;
 191
 192         if (to->ldisc.ops->flush_buffer)
 193                 to->ldisc.ops->flush_buffer(to);
 194
 195         if (to->packet) {
 196                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 197                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 198                 wake_up_interruptible(&to->read_wait);
 199                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 200         }
 201 }
 202
 203 static int pty_open(struct tty_struct *tty, struct file *filp)
 204 {
 205         int     retval = -ENODEV;
 206
 207         if (!tty || !tty->link)
 208                 goto out;
 209
 210         retval = -EIO;
 211         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 212                 goto out;
 213         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 214                 goto out;
 215         if (tty->link->count != 1)
 216                 goto out;
 217
 218         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 219         set_bit(TTY_THROTTLED, &tty->flags);
 220         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 221         retval = 0;
 222 out:
 223         return retval;
 224 }
 225
 226 static void pty_set_termios(struct tty_struct *tty,
 227                                         struct ktermios *old_termios)
 228 {
 229         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 230         tty->termios->c_cflag |= (CS8 | CREAD);
 231 }
 232
 233 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 234 {
 235         struct tty_struct *o_tty;
 236         int idx = tty->index;
 237         int retval;
 238
 239         o_tty = alloc_tty_struct();
 240         if (!o_tty)
 241                 return -ENOMEM;
 242         if (!try_module_get(driver->other->owner)) {
 243                 /* This cannot in fact currently happen */
 244                 free_tty_struct(o_tty);
 245                 return -ENOMEM;
 246         }
 247         initialize_tty_struct(o_tty, driver->other, idx);
 248
 249         /* We always use new tty termios data so we can do this
 250            the easy way .. */
 251         retval = tty_init_termios(tty);
 252         if (retval)
 253                 goto free_mem_out;
 254
 255         retval = tty_init_termios(o_tty);
 256         if (retval) {
 257                 tty_free_termios(tty);
 258                 goto free_mem_out;
 259         }
 260
 261         /*
 262          * Everything allocated ... set up the o_tty structure.
 263          */
 264         driver->other->ttys[idx] = o_tty;
 265         tty_driver_kref_get(driver->other);
 266         if (driver->subtype == PTY_TYPE_MASTER)
 267                 o_tty->count++;
 268         /* Establish the links in both directions */
 269         tty->link   = o_tty;
 270         o_tty->link = tty;
 271
 272         tty_driver_kref_get(driver);
 273         tty->count++;
 274         driver->ttys[idx] = tty;
 275         return 0;
 276 free_mem_out:
 277         module_put(o_tty->driver->owner);
 278         free_tty_struct(o_tty);
 279         return -ENOMEM;
 280 }
 281
 282
 283 static const struct tty_operations pty_ops = {
 284         .install = pty_install,
 285         .open = pty_open,
 286         .close = pty_close,
 287         .write = pty_write,
 288         .write_room = pty_write_room,
 289         .flush_buffer = pty_flush_buffer,
 290         .chars_in_buffer = pty_chars_in_buffer,
 291         .unthrottle = pty_unthrottle,
 292         .set_termios = pty_set_termios,
 293 };
 294
 295 /* Traditional BSD devices */
 296 #ifdef CONFIG_LEGACY_PTYS
 297 static struct tty_driver *pty_driver, *pty_slave_driver;
 298
 299 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 300                          unsigned int cmd, unsigned long arg)
 301 {
 302         switch (cmd) {
 303         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 304                 return pty_set_lock(tty, (int __user *) arg);
 305         }
 306         return -ENOIOCTLCMD;
 307 }
 308
 309 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 310 module_param(legacy_count, int, 0);
 311
 312 static const struct tty_operations pty_ops_bsd = {
 313         .open = pty_open,
 314         .close = pty_close,
 315         .write = pty_write,
 316         .write_room = pty_write_room,
 317         .flush_buffer = pty_flush_buffer,
 318         .chars_in_buffer = pty_chars_in_buffer,
 319         .unthrottle = pty_unthrottle,
 320         .set_termios = pty_set_termios,
 321         .ioctl = pty_bsd_ioctl,
 322 };
 323
 324 static void __init legacy_pty_init(void)
 325 {
 326         if (legacy_count <= 0)
 327                 return;
 328
 329         pty_driver = alloc_tty_driver(legacy_count);
 330         if (!pty_driver)
 331                 panic("Couldn't allocate pty driver");
 332
 333         pty_slave_driver = alloc_tty_driver(legacy_count);
 334         if (!pty_slave_driver)
 335                 panic("Couldn't allocate pty slave driver");
 336
 337         pty_driver->owner = THIS_MODULE;
 338         pty_driver->driver_name = "pty_master";
 339         pty_driver->name = "pty";
 340         pty_driver->major = PTY_MASTER_MAJOR;
 341         pty_driver->minor_start = 0;
 342         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 343         pty_driver->subtype = PTY_TYPE_MASTER;
 344         pty_driver->init_termios = tty_std_termios;
 345         pty_driver->init_termios.c_iflag = 0;
 346         pty_driver->init_termios.c_oflag = 0;
 347         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 348         pty_driver->init_termios.c_lflag = 0;
 349         pty_driver->init_termios.c_ispeed = 38400;
 350         pty_driver->init_termios.c_ospeed = 38400;
 351         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 352         pty_driver->other = pty_slave_driver;
 353         tty_set_operations(pty_driver, &pty_ops);
 354
 355         pty_slave_driver->owner = THIS_MODULE;
 356         pty_slave_driver->driver_name = "pty_slave";
 357         pty_slave_driver->name = "ttyp";
 358         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 359         pty_slave_driver->minor_start = 0;
 360         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 361         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 362         pty_slave_driver->init_termios = tty_std_termios;
 363         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 364         pty_slave_driver->init_termios.c_ispeed = 38400;
 365         pty_slave_driver->init_termios.c_ospeed = 38400;
 366         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 367                                         TTY_DRIVER_REAL_RAW;
 368         pty_slave_driver->other = pty_driver;
 369         tty_set_operations(pty_slave_driver, &pty_ops);
 370
 371         if (tty_register_driver(pty_driver))
 372                 panic("Couldn't register pty driver");
 373         if (tty_register_driver(pty_slave_driver))
 374                 panic("Couldn't register pty slave driver");
 375 }
 376 #else
 377 static inline void legacy_pty_init(void) { }
 378 #endif
 379
 380 /* Unix98 devices */
 381 #ifdef CONFIG_UNIX98_PTYS
 382 /*
 383  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 384  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 385  */
 386 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 387 static int pty_limit_min;
 388 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 389 static int pty_count;
 390
 391 static struct cdev ptmx_cdev;
 392
 393 static struct ctl_table pty_table[] = {
 394         {
 395                 .ctl_name       = PTY_MAX,
 396                 .procname       = "max",
 397                 .maxlen         = sizeof(int),
 398                 .mode           = 0644,
 399                 .data           = &pty_limit,
 400                 .proc_handler   = &proc_dointvec_minmax,
 401                 .strategy       = &sysctl_intvec,
 402                 .extra1         = &pty_limit_min,
 403                 .extra2         = &pty_limit_max,
 404         }, {
 405                 .ctl_name       = PTY_NR,
 406                 .procname       = "nr",
 407                 .maxlen         = sizeof(int),
 408                 .mode           = 0444,
 409                 .data           = &pty_count,
 410                 .proc_handler   = &proc_dointvec,
 411         }, {
 412                 .ctl_name       = 0
 413         }
 414 };
 415
 416 static struct ctl_table pty_kern_table[] = {
 417         {
 418                 .ctl_name       = KERN_PTY,
 419                 .procname       = "pty",
 420                 .mode           = 0555,
 421                 .child          = pty_table,
 422         },
 423         {}
 424 };
 425
 426 static struct ctl_table pty_root_table[] = {
 427         {
 428                 .ctl_name       = CTL_KERN,
 429                 .procname       = "kernel",
 430                 .mode           = 0555,
 431                 .child          = pty_kern_table,
 432         },
 433         {}
 434 };
 435
 436
 437 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 438                             unsigned int cmd, unsigned long arg)
 439 {
 440         switch (cmd) {
 441         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 442                 return pty_set_lock(tty, (int __user *)arg);
 443         case TIOCGPTN: /* Get PT Number */
 444                 return put_user(tty->index, (unsigned int __user *)arg);
 445         }
 446
 447         return -ENOIOCTLCMD;
 448 }
 449
 450 /**
 451  *      ptm_unix98_lookup       -       find a pty master
 452  *      @driver: ptm driver
 453  *      @idx: tty index
 454  *
 455  *      Look up a pty master device. Called under the tty_mutex for now.
 456  *      This provides our locking.
 457  */
 458
 459 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 460                 struct inode *ptm_inode, int idx)
 461 {
 462         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 463         if (tty)
 464                 tty = tty->link;
 465         return tty;
 466 }
 467
 468 /**
 469  *      pts_unix98_lookup       -       find a pty slave
 470  *      @driver: pts driver
 471  *      @idx: tty index
 472  *
 473  *      Look up a pty master device. Called under the tty_mutex for now.
 474  *      This provides our locking.
 475  */
 476
 477 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 478                 struct inode *pts_inode, int idx)
 479 {
 480         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 481         /* Master must be open before slave */
 482         if (!tty)
 483                 return ERR_PTR(-EIO);
 484         return tty;
 485 }
 486
 487 static void pty_unix98_shutdown(struct tty_struct *tty)
 488 {
 489         /* We have our own method as we don't use the tty index */
 490         kfree(tty->termios);
 491         kfree(tty->termios_locked);
 492 }
 493
 494 /* We have no need to install and remove our tty objects as devpts does all
 495    the work for us */
 496
 497 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 498 {
 499         struct tty_struct *o_tty;
 500         int idx = tty->index;
 501
 502         o_tty = alloc_tty_struct();
 503         if (!o_tty)
 504                 return -ENOMEM;
 505         if (!try_module_get(driver->other->owner)) {
 506                 /* This cannot in fact currently happen */
 507                 free_tty_struct(o_tty);
 508                 return -ENOMEM;
 509         }
 510         initialize_tty_struct(o_tty, driver->other, idx);
 511
 512         tty->termios = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
 513         if (tty->termios == NULL)
 514                 goto free_mem_out;
 515         *tty->termios = driver->init_termios;
 516         tty->termios_locked = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
 517         if (tty->termios_locked == NULL)
 518                 goto free_mem_out;
 519         o_tty->termios = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
 520         if (o_tty->termios == NULL)
 521                 goto free_mem_out;
 522         *o_tty->termios = driver->other->init_termios;
 523         o_tty->termios_locked = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
 524         if (o_tty->termios_locked == NULL)
 525                 goto free_mem_out;
 526
 527         tty_driver_kref_get(driver->other);
 528         if (driver->subtype == PTY_TYPE_MASTER)
 529                 o_tty->count++;
 530         /* Establish the links in both directions */
 531         tty->link   = o_tty;
 532         o_tty->link = tty;
 533         /*
 534          * All structures have been allocated, so now we install them.
 535          * Failures after this point use release_tty to clean up, so
 536          * there's no need to null out the local pointers.
 537          */
 538         tty_driver_kref_get(driver);
 539         tty->count++;
 540         pty_count++;
 541         return 0;
 542 free_mem_out:
 543         pty_unix98_shutdown(o_tty);
 544         module_put(o_tty->driver->owner);
 545         free_tty_struct(o_tty);
 546         pty_unix98_shutdown(tty);
 547         return -ENOMEM;
 548 }
 549
 550 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 551 {
 552         pty_count--;
 553 }
 554
 555 static const struct tty_operations ptm_unix98_ops = {
 556         .lookup = ptm_unix98_lookup,
 557         .install = pty_unix98_install,
 558         .remove = pty_unix98_remove,
 559         .open = pty_open,
 560         .close = pty_close,
 561         .write = pty_write,
 562         .write_room = pty_write_room,
 563         .flush_buffer = pty_flush_buffer,
 564         .chars_in_buffer = pty_chars_in_buffer,
 565         .unthrottle = pty_unthrottle,
 566         .set_termios = pty_set_termios,
 567         .ioctl = pty_unix98_ioctl,
 568         .shutdown = pty_unix98_shutdown
 569 };
 570
 571 static const struct tty_operations pty_unix98_ops = {
 572         .lookup = pts_unix98_lookup,
 573         .install = pty_unix98_install,
 574         .remove = pty_unix98_remove,
 575         .open = pty_open,
 576         .close = pty_close,
 577         .write = pty_write,
 578         .write_room = pty_write_room,
 579         .flush_buffer = pty_flush_buffer,
 580         .chars_in_buffer = pty_chars_in_buffer,
 581         .unthrottle = pty_unthrottle,
 582         .set_termios = pty_set_termios,
 583         .shutdown = pty_unix98_shutdown
 584 };
 585
 586 /**
 587  *      ptmx_open               -       open a unix 98 pty master
 588  *      @inode: inode of device file
 589  *      @filp: file pointer to tty
 590  *
 591  *      Allocate a unix98 pty master device from the ptmx driver.
 592  *
 593  *      Locking: tty_mutex protects the init_dev work. tty->count should
 594  *              protect the rest.
 595  *              allocated_ptys_lock handles the list of free pty numbers
 596  */
 597
 598 static int __ptmx_open(struct inode *inode, struct file *filp)
 599 {
 600         struct tty_struct *tty;
 601         int retval;
 602         int index;
 603
 604         nonseekable_open(inode, filp);
 605
 606         /* find a device that is not in use. */
 607         index = devpts_new_index(inode);
 608         if (index < 0)
 609                 return index;
 610
 611         mutex_lock(&tty_mutex);
 612         tty = tty_init_dev(ptm_driver, index, 1);
 613         mutex_unlock(&tty_mutex);
 614
 615         if (IS_ERR(tty)) {
 616                 retval = PTR_ERR(tty);
 617                 goto out;
 618         }
 619
 620         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 621         filp->private_data = tty;
 622         file_move(filp, &tty->tty_files);
 623
 624         retval = devpts_pty_new(inode, tty->link);
 625         if (retval)
 626                 goto out1;
 627
 628         retval = ptm_driver->ops->open(tty, filp);
 629         if (!retval)
 630                 return 0;
 631 out1:
 632         tty_release_dev(filp);
 633         return retval;
 634 out:
 635         devpts_kill_index(inode, index);
 636         return retval;
 637 }
 638
 639 static int ptmx_open(struct inode *inode, struct file *filp)
 640 {
 641         int ret;
 642
 643         lock_kernel();
 644         ret = __ptmx_open(inode, filp);
 645         unlock_kernel();
 646         return ret;
 647 }
 648
 649 static struct file_operations ptmx_fops;
 650
 651 static void __init unix98_pty_init(void)
 652 {
 653         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 654         if (!ptm_driver)
 655                 panic("Couldn't allocate Unix98 ptm driver");
 656         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 657         if (!pts_driver)
 658                 panic("Couldn't allocate Unix98 pts driver");
 659
 660         ptm_driver->owner = THIS_MODULE;
 661         ptm_driver->driver_name = "pty_master";
 662         ptm_driver->name = "ptm";
 663         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 664         ptm_driver->minor_start = 0;
 665         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 666         ptm_driver->subtype = PTY_TYPE_MASTER;
 667         ptm_driver->init_termios = tty_std_termios;
 668         ptm_driver->init_termios.c_iflag = 0;
 669         ptm_driver->init_termios.c_oflag = 0;
 670         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 671         ptm_driver->init_termios.c_lflag = 0;
 672         ptm_driver->init_termios.c_ispeed = 38400;
 673         ptm_driver->init_termios.c_ospeed = 38400;
 674         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 675                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 676         ptm_driver->other = pts_driver;
 677         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 678
 679         pts_driver->owner = THIS_MODULE;
 680         pts_driver->driver_name = "pty_slave";
 681         pts_driver->name = "pts";
 682         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 683         pts_driver->minor_start = 0;
 684         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 685         pts_driver->subtype = PTY_TYPE_SLAVE;
 686         pts_driver->init_termios = tty_std_termios;
 687         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 688         pts_driver->init_termios.c_ispeed = 38400;
 689         pts_driver->init_termios.c_ospeed = 38400;
 690         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 691                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 692         pts_driver->other = ptm_driver;
 693         tty_set_operations(pts_driver, &pty_unix98_ops);
 694
 695         if (tty_register_driver(ptm_driver))
 696                 panic("Couldn't register Unix98 ptm driver");
 697         if (tty_register_driver(pts_driver))
 698                 panic("Couldn't register Unix98 pts driver");
 699
 700         register_sysctl_table(pty_root_table);
 701
 702         /* Now create the /dev/ptmx special device */
 703         tty_default_fops(&ptmx_fops);
 704         ptmx_fops.open = ptmx_open;
 705
 706         cdev_init(&ptmx_cdev, &ptmx_fops);
 707         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 708             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 709                 panic("Couldn't register /dev/ptmx driver\n");
 710         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 711 }
 712
 713 #else
 714 static inline void unix98_pty_init(void) { }
 715 #endif
 716
 717 static int __init pty_init(void)
 718 {
 719         legacy_pty_init();
 720         unix98_pty_init();
 721         return 0;
 722 }
 723 module_init(pty_init);