SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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, int c)
 113 {
 114         struct tty_struct *to = tty->link;
 115
 116         if (tty->stopped)
 117                 return 0;
 118
 119         if (c > 0) {
 120                 /* Stuff the data into the input queue of the other end */
 121                 c = tty_insert_flip_string(to, buf, c);
 122                 /* And shovel */
 123                 if (c) {
 124                         tty_flip_buffer_push(to);
 125                         tty_wakeup(tty);
 126                 }
 127         }
 128         return c;
 129 }
 130
 131 /**
 132  *      pty_write_room  -       write space
 133  *      @tty: tty we are writing from
 134  *
 135  *      Report how many bytes the ldisc can send into the queue for
 136  *      the other device.
 137  */
 138
 139 static int pty_write_room(struct tty_struct *tty)
 140 {
 141         if (tty->stopped)
 142                 return 0;
 143         return pty_space(tty->link);
 144 }
 145
 146 /**
 147  *      pty_chars_in_buffer     -       characters currently in our tx queue
 148  *      @tty: our tty
 149  *
 150  *      Report how much we have in the transmit queue. As everything is
 151  *      instantly at the other end this is easy to implement.
 152  */
 153
 154 static int pty_chars_in_buffer(struct tty_struct *tty)
 155 {
 156         return 0;
 157 }
 158
 159 /* Set the lock flag on a pty */
 160 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 161 {
 162         int val;
 163         if (get_user(val, arg))
 164                 return -EFAULT;
 165         if (val)
 166                 set_bit(TTY_PTY_LOCK, &tty->flags);
 167         else
 168                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 169         return 0;
 170 }
 171
 172 static void pty_flush_buffer(struct tty_struct *tty)
 173 {
 174         struct tty_struct *to = tty->link;
 175         unsigned long flags;
 176
 177         if (!to)
 178                 return;
 179         /* tty_buffer_flush(to); FIXME */
 180         if (to->packet) {
 181                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 182                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 183                 wake_up_interruptible(&to->read_wait);
 184                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 185         }
 186 }
 187
 188 static int pty_open(struct tty_struct *tty, struct file *filp)
 189 {
 190         int     retval = -ENODEV;
 191
 192         if (!tty || !tty->link)
 193                 goto out;
 194
 195         retval = -EIO;
 196         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 197                 goto out;
 198         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 199                 goto out;
 200         if (tty->link->count != 1)
 201                 goto out;
 202
 203         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 204         set_bit(TTY_THROTTLED, &tty->flags);
 205         retval = 0;
 206 out:
 207         return retval;
 208 }
 209
 210 static void pty_set_termios(struct tty_struct *tty,
 211                                         struct ktermios *old_termios)
 212 {
 213         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 214         tty->termios->c_cflag |= (CS8 | CREAD);
 215 }
 216
 217 /**
 218  *      pty_do_resize           -       resize event
 219  *      @tty: tty being resized
 220  *      @ws: window size being set.
 221  *
 222  *      Update the termios variables and send the neccessary signals to
 223  *      peform a terminal resize correctly
 224  */
 225
 226 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 227 {
 228         struct pid *pgrp, *rpgrp;
 229         unsigned long flags;
 230         struct tty_struct *pty = tty->link;
 231
 232         /* For a PTY we need to lock the tty side */
 233         mutex_lock(&tty->termios_mutex);
 234         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 235                 goto done;
 236
 237         /* Get the PID values and reference them so we can
 238            avoid holding the tty ctrl lock while sending signals.
 239            We need to lock these individually however. */
 240
 241         spin_lock_irqsave(&tty->ctrl_lock, flags);
 242         pgrp = get_pid(tty->pgrp);
 243         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 244
 245         spin_lock_irqsave(&pty->ctrl_lock, flags);
 246         rpgrp = get_pid(pty->pgrp);
 247         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 248
 249         if (pgrp)
 250                 kill_pgrp(pgrp, SIGWINCH, 1);
 251         if (rpgrp != pgrp && rpgrp)
 252                 kill_pgrp(rpgrp, SIGWINCH, 1);
 253
 254         put_pid(pgrp);
 255         put_pid(rpgrp);
 256
 257         tty->winsize = *ws;
 258         pty->winsize = *ws;     /* Never used so will go away soon */
 259 done:
 260         mutex_unlock(&tty->termios_mutex);
 261         return 0;
 262 }
 263
 264 /* Traditional BSD devices */
 265 #ifdef CONFIG_LEGACY_PTYS
 266
 267 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 268 {
 269         struct tty_struct *o_tty;
 270         int idx = tty->index;
 271         int retval;
 272
 273         o_tty = alloc_tty_struct();
 274         if (!o_tty)
 275                 return -ENOMEM;
 276         if (!try_module_get(driver->other->owner)) {
 277                 /* This cannot in fact currently happen */
 278                 free_tty_struct(o_tty);
 279                 return -ENOMEM;
 280         }
 281         initialize_tty_struct(o_tty, driver->other, idx);
 282
 283         /* We always use new tty termios data so we can do this
 284            the easy way .. */
 285         retval = tty_init_termios(tty);
 286         if (retval)
 287                 goto free_mem_out;
 288
 289         retval = tty_init_termios(o_tty);
 290         if (retval) {
 291                 tty_free_termios(tty);
 292                 goto free_mem_out;
 293         }
 294
 295         /*
 296          * Everything allocated ... set up the o_tty structure.
 297          */
 298         driver->other->ttys[idx] = o_tty;
 299         tty_driver_kref_get(driver->other);
 300         if (driver->subtype == PTY_TYPE_MASTER)
 301                 o_tty->count++;
 302         /* Establish the links in both directions */
 303         tty->link   = o_tty;
 304         o_tty->link = tty;
 305
 306         tty_driver_kref_get(driver);
 307         tty->count++;
 308         driver->ttys[idx] = tty;
 309         return 0;
 310 free_mem_out:
 311         module_put(o_tty->driver->owner);
 312         free_tty_struct(o_tty);
 313         return -ENOMEM;
 314 }
 315
 316 static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
 317                          unsigned int cmd, unsigned long arg)
 318 {
 319         switch (cmd) {
 320         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 321                 return pty_set_lock(tty, (int __user *) arg);
 322         }
 323         return -ENOIOCTLCMD;
 324 }
 325
 326 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 327 module_param(legacy_count, int, 0);
 328
 329 /*
 330  * The master side of a pty can do TIOCSPTLCK and thus
 331  * has pty_bsd_ioctl.
 332  */
 333 static const struct tty_operations master_pty_ops_bsd = {
 334         .install = pty_install,
 335         .open = pty_open,
 336         .close = pty_close,
 337         .write = pty_write,
 338         .write_room = pty_write_room,
 339         .flush_buffer = pty_flush_buffer,
 340         .chars_in_buffer = pty_chars_in_buffer,
 341         .unthrottle = pty_unthrottle,
 342         .set_termios = pty_set_termios,
 343         .ioctl = pty_bsd_ioctl,
 344         .resize = pty_resize
 345 };
 346
 347 static const struct tty_operations slave_pty_ops_bsd = {
 348         .install = pty_install,
 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         .resize = pty_resize
 358 };
 359
 360 static void __init legacy_pty_init(void)
 361 {
 362         struct tty_driver *pty_driver, *pty_slave_driver;
 363
 364         if (legacy_count <= 0)
 365                 return;
 366
 367         pty_driver = alloc_tty_driver(legacy_count);
 368         if (!pty_driver)
 369                 panic("Couldn't allocate pty driver");
 370
 371         pty_slave_driver = alloc_tty_driver(legacy_count);
 372         if (!pty_slave_driver)
 373                 panic("Couldn't allocate pty slave driver");
 374
 375         pty_driver->owner = THIS_MODULE;
 376         pty_driver->driver_name = "pty_master";
 377         pty_driver->name = "pty";
 378         pty_driver->major = PTY_MASTER_MAJOR;
 379         pty_driver->minor_start = 0;
 380         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 381         pty_driver->subtype = PTY_TYPE_MASTER;
 382         pty_driver->init_termios = tty_std_termios;
 383         pty_driver->init_termios.c_iflag = 0;
 384         pty_driver->init_termios.c_oflag = 0;
 385         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 386         pty_driver->init_termios.c_lflag = 0;
 387         pty_driver->init_termios.c_ispeed = 38400;
 388         pty_driver->init_termios.c_ospeed = 38400;
 389         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 390         pty_driver->other = pty_slave_driver;
 391         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 392
 393         pty_slave_driver->owner = THIS_MODULE;
 394         pty_slave_driver->driver_name = "pty_slave";
 395         pty_slave_driver->name = "ttyp";
 396         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 397         pty_slave_driver->minor_start = 0;
 398         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 399         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 400         pty_slave_driver->init_termios = tty_std_termios;
 401         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 402         pty_slave_driver->init_termios.c_ispeed = 38400;
 403         pty_slave_driver->init_termios.c_ospeed = 38400;
 404         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 405                                         TTY_DRIVER_REAL_RAW;
 406         pty_slave_driver->other = pty_driver;
 407         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 408
 409         if (tty_register_driver(pty_driver))
 410                 panic("Couldn't register pty driver");
 411         if (tty_register_driver(pty_slave_driver))
 412                 panic("Couldn't register pty slave driver");
 413 }
 414 #else
 415 static inline void legacy_pty_init(void) { }
 416 #endif
 417
 418 /* Unix98 devices */
 419 #ifdef CONFIG_UNIX98_PTYS
 420 /*
 421  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 422  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 423  */
 424 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 425 static int pty_limit_min;
 426 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 427 static int pty_count;
 428
 429 static struct cdev ptmx_cdev;
 430
 431 static struct ctl_table pty_table[] = {
 432         {
 433                 .ctl_name       = PTY_MAX,
 434                 .procname       = "max",
 435                 .maxlen         = sizeof(int),
 436                 .mode           = 0644,
 437                 .data           = &pty_limit,
 438                 .proc_handler   = &proc_dointvec_minmax,
 439                 .strategy       = &sysctl_intvec,
 440                 .extra1         = &pty_limit_min,
 441                 .extra2         = &pty_limit_max,
 442         }, {
 443                 .ctl_name       = PTY_NR,
 444                 .procname       = "nr",
 445                 .maxlen         = sizeof(int),
 446                 .mode           = 0444,
 447                 .data           = &pty_count,
 448                 .proc_handler   = &proc_dointvec,
 449         }, {
 450                 .ctl_name       = 0
 451         }
 452 };
 453
 454 static struct ctl_table pty_kern_table[] = {
 455         {
 456                 .ctl_name       = KERN_PTY,
 457                 .procname       = "pty",
 458                 .mode           = 0555,
 459                 .child          = pty_table,
 460         },
 461         {}
 462 };
 463
 464 static struct ctl_table pty_root_table[] = {
 465         {
 466                 .ctl_name       = CTL_KERN,
 467                 .procname       = "kernel",
 468                 .mode           = 0555,
 469                 .child          = pty_kern_table,
 470         },
 471         {}
 472 };
 473
 474
 475 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 476                             unsigned int cmd, unsigned long arg)
 477 {
 478         switch (cmd) {
 479         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 480                 return pty_set_lock(tty, (int __user *)arg);
 481         case TIOCGPTN: /* Get PT Number */
 482                 return put_user(tty->index, (unsigned int __user *)arg);
 483         }
 484
 485         return -ENOIOCTLCMD;
 486 }
 487
 488 /**
 489  *      ptm_unix98_lookup       -       find a pty master
 490  *      @driver: ptm driver
 491  *      @idx: tty index
 492  *
 493  *      Look up a pty master device. Called under the tty_mutex for now.
 494  *      This provides our locking.
 495  */
 496
 497 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 498                 struct inode *ptm_inode, int idx)
 499 {
 500         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 501         if (tty)
 502                 tty = tty->link;
 503         return tty;
 504 }
 505
 506 /**
 507  *      pts_unix98_lookup       -       find a pty slave
 508  *      @driver: pts driver
 509  *      @idx: tty index
 510  *
 511  *      Look up a pty master device. Called under the tty_mutex for now.
 512  *      This provides our locking.
 513  */
 514
 515 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 516                 struct inode *pts_inode, int idx)
 517 {
 518         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 519         /* Master must be open before slave */
 520         if (!tty)
 521                 return ERR_PTR(-EIO);
 522         return tty;
 523 }
 524
 525 static void pty_unix98_shutdown(struct tty_struct *tty)
 526 {
 527         /* We have our own method as we don't use the tty index */
 528         kfree(tty->termios);
 529 }
 530
 531 /* We have no need to install and remove our tty objects as devpts does all
 532    the work for us */
 533
 534 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 535 {
 536         struct tty_struct *o_tty;
 537         int idx = tty->index;
 538
 539         o_tty = alloc_tty_struct();
 540         if (!o_tty)
 541                 return -ENOMEM;
 542         if (!try_module_get(driver->other->owner)) {
 543                 /* This cannot in fact currently happen */
 544                 free_tty_struct(o_tty);
 545                 return -ENOMEM;
 546         }
 547         initialize_tty_struct(o_tty, driver->other, idx);
 548
 549         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 550         if (tty->termios == NULL)
 551                 goto free_mem_out;
 552         *tty->termios = driver->init_termios;
 553         tty->termios_locked = tty->termios + 1;
 554
 555         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 556         if (o_tty->termios == NULL)
 557                 goto free_mem_out;
 558         *o_tty->termios = driver->other->init_termios;
 559         o_tty->termios_locked = o_tty->termios + 1;
 560
 561         tty_driver_kref_get(driver->other);
 562         if (driver->subtype == PTY_TYPE_MASTER)
 563                 o_tty->count++;
 564         /* Establish the links in both directions */
 565         tty->link   = o_tty;
 566         o_tty->link = tty;
 567         /*
 568          * All structures have been allocated, so now we install them.
 569          * Failures after this point use release_tty to clean up, so
 570          * there's no need to null out the local pointers.
 571          */
 572         tty_driver_kref_get(driver);
 573         tty->count++;
 574         pty_count++;
 575         return 0;
 576 free_mem_out:
 577         kfree(o_tty->termios);
 578         module_put(o_tty->driver->owner);
 579         free_tty_struct(o_tty);
 580         kfree(tty->termios);
 581         return -ENOMEM;
 582 }
 583
 584 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 585 {
 586         pty_count--;
 587 }
 588
 589 static const struct tty_operations ptm_unix98_ops = {
 590         .lookup = ptm_unix98_lookup,
 591         .install = pty_unix98_install,
 592         .remove = pty_unix98_remove,
 593         .open = pty_open,
 594         .close = pty_close,
 595         .write = pty_write,
 596         .write_room = pty_write_room,
 597         .flush_buffer = pty_flush_buffer,
 598         .chars_in_buffer = pty_chars_in_buffer,
 599         .unthrottle = pty_unthrottle,
 600         .set_termios = pty_set_termios,
 601         .ioctl = pty_unix98_ioctl,
 602         .shutdown = pty_unix98_shutdown,
 603         .resize = pty_resize
 604 };
 605
 606 static const struct tty_operations pty_unix98_ops = {
 607         .lookup = pts_unix98_lookup,
 608         .install = pty_unix98_install,
 609         .remove = pty_unix98_remove,
 610         .open = pty_open,
 611         .close = pty_close,
 612         .write = pty_write,
 613         .write_room = pty_write_room,
 614         .flush_buffer = pty_flush_buffer,
 615         .chars_in_buffer = pty_chars_in_buffer,
 616         .unthrottle = pty_unthrottle,
 617         .set_termios = pty_set_termios,
 618         .shutdown = pty_unix98_shutdown
 619 };
 620
 621 /**
 622  *      ptmx_open               -       open a unix 98 pty master
 623  *      @inode: inode of device file
 624  *      @filp: file pointer to tty
 625  *
 626  *      Allocate a unix98 pty master device from the ptmx driver.
 627  *
 628  *      Locking: tty_mutex protects the init_dev work. tty->count should
 629  *              protect the rest.
 630  *              allocated_ptys_lock handles the list of free pty numbers
 631  */
 632
 633 static int __ptmx_open(struct inode *inode, struct file *filp)
 634 {
 635         struct tty_struct *tty;
 636         int retval;
 637         int index;
 638
 639         nonseekable_open(inode, filp);
 640
 641         /* find a device that is not in use. */
 642         index = devpts_new_index(inode);
 643         if (index < 0)
 644                 return index;
 645
 646         mutex_lock(&tty_mutex);
 647         tty = tty_init_dev(ptm_driver, index, 1);
 648         mutex_unlock(&tty_mutex);
 649
 650         if (IS_ERR(tty)) {
 651                 retval = PTR_ERR(tty);
 652                 goto out;
 653         }
 654
 655         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 656         filp->private_data = tty;
 657         file_move(filp, &tty->tty_files);
 658
 659         retval = devpts_pty_new(inode, tty->link);
 660         if (retval)
 661                 goto out1;
 662
 663         retval = ptm_driver->ops->open(tty, filp);
 664         if (!retval)
 665                 return 0;
 666 out1:
 667         tty_release_dev(filp);
 668         return retval;
 669 out:
 670         devpts_kill_index(inode, index);
 671         return retval;
 672 }
 673
 674 static int ptmx_open(struct inode *inode, struct file *filp)
 675 {
 676         int ret;
 677
 678         lock_kernel();
 679         ret = __ptmx_open(inode, filp);
 680         unlock_kernel();
 681         return ret;
 682 }
 683
 684 static struct file_operations ptmx_fops;
 685
 686 static void __init unix98_pty_init(void)
 687 {
 688         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 689         if (!ptm_driver)
 690                 panic("Couldn't allocate Unix98 ptm driver");
 691         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 692         if (!pts_driver)
 693                 panic("Couldn't allocate Unix98 pts driver");
 694
 695         ptm_driver->owner = THIS_MODULE;
 696         ptm_driver->driver_name = "pty_master";
 697         ptm_driver->name = "ptm";
 698         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 699         ptm_driver->minor_start = 0;
 700         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 701         ptm_driver->subtype = PTY_TYPE_MASTER;
 702         ptm_driver->init_termios = tty_std_termios;
 703         ptm_driver->init_termios.c_iflag = 0;
 704         ptm_driver->init_termios.c_oflag = 0;
 705         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 706         ptm_driver->init_termios.c_lflag = 0;
 707         ptm_driver->init_termios.c_ispeed = 38400;
 708         ptm_driver->init_termios.c_ospeed = 38400;
 709         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 710                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 711         ptm_driver->other = pts_driver;
 712         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 713
 714         pts_driver->owner = THIS_MODULE;
 715         pts_driver->driver_name = "pty_slave";
 716         pts_driver->name = "pts";
 717         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 718         pts_driver->minor_start = 0;
 719         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 720         pts_driver->subtype = PTY_TYPE_SLAVE;
 721         pts_driver->init_termios = tty_std_termios;
 722         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 723         pts_driver->init_termios.c_ispeed = 38400;
 724         pts_driver->init_termios.c_ospeed = 38400;
 725         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 726                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 727         pts_driver->other = ptm_driver;
 728         tty_set_operations(pts_driver, &pty_unix98_ops);
 729
 730         if (tty_register_driver(ptm_driver))
 731                 panic("Couldn't register Unix98 ptm driver");
 732         if (tty_register_driver(pts_driver))
 733                 panic("Couldn't register Unix98 pts driver");
 734
 735         register_sysctl_table(pty_root_table);
 736
 737         /* Now create the /dev/ptmx special device */
 738         tty_default_fops(&ptmx_fops);
 739         ptmx_fops.open = ptmx_open;
 740
 741         cdev_init(&ptmx_cdev, &ptmx_fops);
 742         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 743             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 744                 panic("Couldn't register /dev/ptmx driver\n");
 745         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 746 }
 747
 748 #else
 749 static inline void unix98_pty_init(void) { }
 750 #endif
 751
 752 static int __init pty_init(void)
 753 {
 754         legacy_pty_init();
 755         unix98_pty_init();
 756         return 0;
 757 }
 758 module_init(pty_init);