drivers/tty/pty.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  Added support for a Unix98-style ptmx device.
   5  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   6  *
   7  */
   8
   9 #include <linux/module.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/tty.h>
  14 #include <linux/tty_flip.h>
  15 #include <linux/fcntl.h>
  16 #include <linux/sched.h>
  17 #include <linux/string.h>
  18 #include <linux/major.h>
  19 #include <linux/mm.h>
  20 #include <linux/init.h>
  21 #include <linux/device.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/bitops.h>
  24 #include <linux/devpts_fs.h>
  25 #include <linux/slab.h>
  26 #include <linux/mutex.h>
  27 #include <linux/poll.h>
  28
  29
  30 #ifdef CONFIG_UNIX98_PTYS
  31 static struct tty_driver *ptm_driver;
  32 static struct tty_driver *pts_driver;
  33 static DEFINE_MUTEX(devpts_mutex);
  34 #endif
  35
  36 static void pty_close(struct tty_struct *tty, struct file *filp)
  37 {
  38         BUG_ON(!tty);
  39         if (tty->driver->subtype == PTY_TYPE_MASTER)
  40                 WARN_ON(tty->count > 1);
  41         else {
  42                 if (test_bit(TTY_IO_ERROR, &tty->flags))
  43                         return;
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         set_bit(TTY_IO_ERROR, &tty->flags);
  48         wake_up_interruptible(&tty->read_wait);
  49         wake_up_interruptible(&tty->write_wait);
  50         tty->packet = 0;
  51         /* Review - krefs on tty_link ?? */
  52         if (!tty->link)
  53                 return;
  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                         mutex_lock(&devpts_mutex);
  62                         if (tty->link->driver_data)
  63                                 devpts_pty_kill(tty->link->driver_data);
  64                         mutex_unlock(&devpts_mutex);
  65                 }
  66 #endif
  67                 tty_unlock(tty);
  68                 tty_vhangup(tty->link);
  69                 tty_lock(tty);
  70         }
  71 }
  72
  73 /*
  74  * The unthrottle routine is called by the line discipline to signal
  75  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  76  * flag is always set, to force the line discipline to always call the
  77  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  78  * characters in the queue.  This is necessary since each time this
  79  * happens, we need to wake up any sleeping processes that could be
  80  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  81  * for the pty buffer to be drained.
  82  */
  83 static void pty_unthrottle(struct tty_struct *tty)
  84 {
  85         tty_wakeup(tty->link);
  86         set_bit(TTY_THROTTLED, &tty->flags);
  87 }
  88
  89 /**
  90  *      pty_space       -       report space left for writing
  91  *      @to: tty we are writing into
  92  *
  93  *      Limit the buffer space used by ptys to 8k.
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = tty_buffer_space_avail(to->port);
  99         return min(n, 8192);
 100 }
 101
 102 /**
 103  *      pty_write               -       write to a pty
 104  *      @tty: the tty we write from
 105  *      @buf: kernel buffer of data
 106  *      @count: bytes to write
 107  *
 108  *      Our "hardware" write method. Data is coming from the ldisc which
 109  *      may be in a non sleeping state. We simply throw this at the other
 110  *      end of the link as if we were an IRQ handler receiving stuff for
 111  *      the other side of the pty/tty pair.
 112  */
 113
 114 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 115 {
 116         struct tty_struct *to = tty->link;
 117
 118         if (tty->stopped)
 119                 return 0;
 120
 121         if (c > 0) {
 122                 /* Stuff the data into the input queue of the other end */
 123                 c = tty_insert_flip_string(to->port, buf, c);
 124                 /* And shovel */
 125                 if (c)
 126                         tty_flip_buffer_push(to->port);
 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 int pty_get_lock(struct tty_struct *tty, int __user *arg)
 173 {
 174         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
 175         return put_user(locked, arg);
 176 }
 177
 178 /* Set the packet mode on a pty */
 179 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 180 {
 181         unsigned long flags;
 182         int pktmode;
 183
 184         if (get_user(pktmode, arg))
 185                 return -EFAULT;
 186
 187         spin_lock_irqsave(&tty->ctrl_lock, flags);
 188         if (pktmode) {
 189                 if (!tty->packet) {
 190                         tty->packet = 1;
 191                         tty->link->ctrl_status = 0;
 192                 }
 193         } else
 194                 tty->packet = 0;
 195         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 196
 197         return 0;
 198 }
 199
 200 /* Get the packet mode of a pty */
 201 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
 202 {
 203         int pktmode = tty->packet;
 204         return put_user(pktmode, arg);
 205 }
 206
 207 /* Send a signal to the slave */
 208 static int pty_signal(struct tty_struct *tty, int sig)
 209 {
 210         unsigned long flags;
 211         struct pid *pgrp;
 212
 213         if (tty->link) {
 214                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 215                 pgrp = get_pid(tty->link->pgrp);
 216                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 217
 218                 kill_pgrp(pgrp, sig, 1);
 219                 put_pid(pgrp);
 220         }
 221         return 0;
 222 }
 223
 224 static void pty_flush_buffer(struct tty_struct *tty)
 225 {
 226         struct tty_struct *to = tty->link;
 227         unsigned long flags;
 228
 229         if (!to)
 230                 return;
 231         /* tty_buffer_flush(to); FIXME */
 232         if (to->packet) {
 233                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 234                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 235                 wake_up_interruptible(&to->read_wait);
 236                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 237         }
 238 }
 239
 240 static int pty_open(struct tty_struct *tty, struct file *filp)
 241 {
 242         if (!tty || !tty->link)
 243                 return -ENODEV;
 244
 245         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 246                 goto out;
 247         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 248                 goto out;
 249         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 250                 goto out;
 251
 252         clear_bit(TTY_IO_ERROR, &tty->flags);
 253         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 254         set_bit(TTY_THROTTLED, &tty->flags);
 255         return 0;
 256
 257 out:
 258         set_bit(TTY_IO_ERROR, &tty->flags);
 259         return -EIO;
 260 }
 261
 262 static void pty_set_termios(struct tty_struct *tty,
 263                                         struct ktermios *old_termios)
 264 {
 265         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 266         tty->termios.c_cflag |= (CS8 | CREAD);
 267 }
 268
 269 /**
 270  *      pty_do_resize           -       resize event
 271  *      @tty: tty being resized
 272  *      @ws: window size being set.
 273  *
 274  *      Update the termios variables and send the necessary signals to
 275  *      peform a terminal resize correctly
 276  */
 277
 278 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 279 {
 280         struct pid *pgrp, *rpgrp;
 281         unsigned long flags;
 282         struct tty_struct *pty = tty->link;
 283
 284         /* For a PTY we need to lock the tty side */
 285         mutex_lock(&tty->winsize_mutex);
 286         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 287                 goto done;
 288
 289         /* Get the PID values and reference them so we can
 290            avoid holding the tty ctrl lock while sending signals.
 291            We need to lock these individually however. */
 292
 293         spin_lock_irqsave(&tty->ctrl_lock, flags);
 294         pgrp = get_pid(tty->pgrp);
 295         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 296
 297         spin_lock_irqsave(&pty->ctrl_lock, flags);
 298         rpgrp = get_pid(pty->pgrp);
 299         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 300
 301         if (pgrp)
 302                 kill_pgrp(pgrp, SIGWINCH, 1);
 303         if (rpgrp != pgrp && rpgrp)
 304                 kill_pgrp(rpgrp, SIGWINCH, 1);
 305
 306         put_pid(pgrp);
 307         put_pid(rpgrp);
 308
 309         tty->winsize = *ws;
 310         pty->winsize = *ws;     /* Never used so will go away soon */
 311 done:
 312         mutex_unlock(&tty->winsize_mutex);
 313         return 0;
 314 }
 315
 316 /**
 317  *      pty_start - start() handler
 318  *      pty_stop  - stop() handler
 319  *      @tty: tty being flow-controlled
 320  *
 321  *      Propagates the TIOCPKT status to the master pty.
 322  *
 323  *      NB: only the master pty can be in packet mode so only the slave
 324  *          needs start()/stop() handlers
 325  */
 326 static void pty_start(struct tty_struct *tty)
 327 {
 328         unsigned long flags;
 329
 330         spin_lock_irqsave(&tty->ctrl_lock, flags);
 331         if (tty->link && tty->link->packet) {
 332                 tty->ctrl_status &= ~TIOCPKT_STOP;
 333                 tty->ctrl_status |= TIOCPKT_START;
 334                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 335         }
 336         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 337 }
 338
 339 static void pty_stop(struct tty_struct *tty)
 340 {
 341         unsigned long flags;
 342
 343         spin_lock_irqsave(&tty->ctrl_lock, flags);
 344         if (tty->link && tty->link->packet) {
 345                 tty->ctrl_status &= ~TIOCPKT_START;
 346                 tty->ctrl_status |= TIOCPKT_STOP;
 347                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 348         }
 349         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 350 }
 351
 352 /**
 353  *      pty_common_install              -       set up the pty pair
 354  *      @driver: the pty driver
 355  *      @tty: the tty being instantiated
 356  *      @legacy: true if this is BSD style
 357  *
 358  *      Perform the initial set up for the tty/pty pair. Called from the
 359  *      tty layer when the port is first opened.
 360  *
 361  *      Locking: the caller must hold the tty_mutex
 362  */
 363 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 364                 bool legacy)
 365 {
 366         struct tty_struct *o_tty;
 367         struct tty_port *ports[2];
 368         int idx = tty->index;
 369         int retval = -ENOMEM;
 370
 371         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 372         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 373         if (!ports[0] || !ports[1])
 374                 goto err;
 375         if (!try_module_get(driver->other->owner)) {
 376                 /* This cannot in fact currently happen */
 377                 goto err;
 378         }
 379         o_tty = alloc_tty_struct(driver->other, idx);
 380         if (!o_tty)
 381                 goto err_put_module;
 382
 383         if (legacy) {
 384                 /* We always use new tty termios data so we can do this
 385                    the easy way .. */
 386                 retval = tty_init_termios(tty);
 387                 if (retval)
 388                         goto err_deinit_tty;
 389
 390                 retval = tty_init_termios(o_tty);
 391                 if (retval)
 392                         goto err_free_termios;
 393
 394                 driver->other->ttys[idx] = o_tty;
 395                 driver->ttys[idx] = tty;
 396         } else {
 397                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 398                 tty->termios = driver->init_termios;
 399                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 400                 o_tty->termios = driver->other->init_termios;
 401         }
 402
 403         /*
 404          * Everything allocated ... set up the o_tty structure.
 405          */
 406         tty_driver_kref_get(driver->other);
 407         if (driver->subtype == PTY_TYPE_MASTER)
 408                 o_tty->count++;
 409         /* Establish the links in both directions */
 410         tty->link   = o_tty;
 411         o_tty->link = tty;
 412         tty_port_init(ports[0]);
 413         tty_port_init(ports[1]);
 414         o_tty->port = ports[0];
 415         tty->port = ports[1];
 416         o_tty->port->itty = o_tty;
 417
 418         tty_driver_kref_get(driver);
 419         tty->count++;
 420         return 0;
 421 err_free_termios:
 422         if (legacy)
 423                 tty_free_termios(tty);
 424 err_deinit_tty:
 425         deinitialize_tty_struct(o_tty);
 426         free_tty_struct(o_tty);
 427 err_put_module:
 428         module_put(driver->other->owner);
 429 err:
 430         kfree(ports[0]);
 431         kfree(ports[1]);
 432         return retval;
 433 }
 434
 435 static void pty_cleanup(struct tty_struct *tty)
 436 {
 437         tty_port_put(tty->port);
 438 }
 439
 440 /* Traditional BSD devices */
 441 #ifdef CONFIG_LEGACY_PTYS
 442
 443 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 444 {
 445         return pty_common_install(driver, tty, true);
 446 }
 447
 448 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 449 {
 450         struct tty_struct *pair = tty->link;
 451         driver->ttys[tty->index] = NULL;
 452         if (pair)
 453                 pair->driver->ttys[pair->index] = NULL;
 454 }
 455
 456 static int pty_bsd_ioctl(struct tty_struct *tty,
 457                          unsigned int cmd, unsigned long arg)
 458 {
 459         switch (cmd) {
 460         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 461                 return pty_set_lock(tty, (int __user *) arg);
 462         case TIOCGPTLCK: /* Get PT Lock status */
 463                 return pty_get_lock(tty, (int __user *)arg);
 464         case TIOCPKT: /* Set PT packet mode */
 465                 return pty_set_pktmode(tty, (int __user *)arg);
 466         case TIOCGPKT: /* Get PT packet mode */
 467                 return pty_get_pktmode(tty, (int __user *)arg);
 468         case TIOCSIG:    /* Send signal to other side of pty */
 469                 return pty_signal(tty, (int) arg);
 470         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 471                 return -EINVAL;
 472         }
 473         return -ENOIOCTLCMD;
 474 }
 475
 476 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 477 module_param(legacy_count, int, 0);
 478
 479 /*
 480  * The master side of a pty can do TIOCSPTLCK and thus
 481  * has pty_bsd_ioctl.
 482  */
 483 static const struct tty_operations master_pty_ops_bsd = {
 484         .install = pty_install,
 485         .open = pty_open,
 486         .close = pty_close,
 487         .write = pty_write,
 488         .write_room = pty_write_room,
 489         .flush_buffer = pty_flush_buffer,
 490         .chars_in_buffer = pty_chars_in_buffer,
 491         .unthrottle = pty_unthrottle,
 492         .set_termios = pty_set_termios,
 493         .ioctl = pty_bsd_ioctl,
 494         .cleanup = pty_cleanup,
 495         .resize = pty_resize,
 496         .remove = pty_remove
 497 };
 498
 499 static const struct tty_operations slave_pty_ops_bsd = {
 500         .install = pty_install,
 501         .open = pty_open,
 502         .close = pty_close,
 503         .write = pty_write,
 504         .write_room = pty_write_room,
 505         .flush_buffer = pty_flush_buffer,
 506         .chars_in_buffer = pty_chars_in_buffer,
 507         .unthrottle = pty_unthrottle,
 508         .set_termios = pty_set_termios,
 509         .cleanup = pty_cleanup,
 510         .resize = pty_resize,
 511         .start = pty_start,
 512         .stop = pty_stop,
 513         .remove = pty_remove
 514 };
 515
 516 static void __init legacy_pty_init(void)
 517 {
 518         struct tty_driver *pty_driver, *pty_slave_driver;
 519
 520         if (legacy_count <= 0)
 521                 return;
 522
 523         pty_driver = tty_alloc_driver(legacy_count,
 524                         TTY_DRIVER_RESET_TERMIOS |
 525                         TTY_DRIVER_REAL_RAW |
 526                         TTY_DRIVER_DYNAMIC_ALLOC);
 527         if (IS_ERR(pty_driver))
 528                 panic("Couldn't allocate pty driver");
 529
 530         pty_slave_driver = tty_alloc_driver(legacy_count,
 531                         TTY_DRIVER_RESET_TERMIOS |
 532                         TTY_DRIVER_REAL_RAW |
 533                         TTY_DRIVER_DYNAMIC_ALLOC);
 534         if (IS_ERR(pty_slave_driver))
 535                 panic("Couldn't allocate pty slave driver");
 536
 537         pty_driver->driver_name = "pty_master";
 538         pty_driver->name = "pty";
 539         pty_driver->major = PTY_MASTER_MAJOR;
 540         pty_driver->minor_start = 0;
 541         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 542         pty_driver->subtype = PTY_TYPE_MASTER;
 543         pty_driver->init_termios = tty_std_termios;
 544         pty_driver->init_termios.c_iflag = 0;
 545         pty_driver->init_termios.c_oflag = 0;
 546         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 547         pty_driver->init_termios.c_lflag = 0;
 548         pty_driver->init_termios.c_ispeed = 38400;
 549         pty_driver->init_termios.c_ospeed = 38400;
 550         pty_driver->other = pty_slave_driver;
 551         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 552
 553         pty_slave_driver->driver_name = "pty_slave";
 554         pty_slave_driver->name = "ttyp";
 555         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 556         pty_slave_driver->minor_start = 0;
 557         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 558         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 559         pty_slave_driver->init_termios = tty_std_termios;
 560         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 561         pty_slave_driver->init_termios.c_ispeed = 38400;
 562         pty_slave_driver->init_termios.c_ospeed = 38400;
 563         pty_slave_driver->other = pty_driver;
 564         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 565
 566         if (tty_register_driver(pty_driver))
 567                 panic("Couldn't register pty driver");
 568         if (tty_register_driver(pty_slave_driver))
 569                 panic("Couldn't register pty slave driver");
 570 }
 571 #else
 572 static inline void legacy_pty_init(void) { }
 573 #endif
 574
 575 /* Unix98 devices */
 576 #ifdef CONFIG_UNIX98_PTYS
 577
 578 static struct cdev ptmx_cdev;
 579
 580 static int pty_unix98_ioctl(struct tty_struct *tty,
 581                             unsigned int cmd, unsigned long arg)
 582 {
 583         switch (cmd) {
 584         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 585                 return pty_set_lock(tty, (int __user *)arg);
 586         case TIOCGPTLCK: /* Get PT Lock status */
 587                 return pty_get_lock(tty, (int __user *)arg);
 588         case TIOCPKT: /* Set PT packet mode */
 589                 return pty_set_pktmode(tty, (int __user *)arg);
 590         case TIOCGPKT: /* Get PT packet mode */
 591                 return pty_get_pktmode(tty, (int __user *)arg);
 592         case TIOCGPTN: /* Get PT Number */
 593                 return put_user(tty->index, (unsigned int __user *)arg);
 594         case TIOCSIG:    /* Send signal to other side of pty */
 595                 return pty_signal(tty, (int) arg);
 596         }
 597
 598         return -ENOIOCTLCMD;
 599 }
 600
 601 /**
 602  *      ptm_unix98_lookup       -       find a pty master
 603  *      @driver: ptm driver
 604  *      @idx: tty index
 605  *
 606  *      Look up a pty master device. Called under the tty_mutex for now.
 607  *      This provides our locking.
 608  */
 609
 610 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 611                 struct inode *ptm_inode, int idx)
 612 {
 613         /* Master must be open via /dev/ptmx */
 614         return ERR_PTR(-EIO);
 615 }
 616
 617 /**
 618  *      pts_unix98_lookup       -       find a pty slave
 619  *      @driver: pts driver
 620  *      @idx: tty index
 621  *
 622  *      Look up a pty master device. Called under the tty_mutex for now.
 623  *      This provides our locking for the tty pointer.
 624  */
 625
 626 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 627                 struct inode *pts_inode, int idx)
 628 {
 629         struct tty_struct *tty;
 630
 631         mutex_lock(&devpts_mutex);
 632         tty = devpts_get_priv(pts_inode);
 633         mutex_unlock(&devpts_mutex);
 634         /* Master must be open before slave */
 635         if (!tty)
 636                 return ERR_PTR(-EIO);
 637         return tty;
 638 }
 639
 640 /* We have no need to install and remove our tty objects as devpts does all
 641    the work for us */
 642
 643 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 644 {
 645         return pty_common_install(driver, tty, false);
 646 }
 647
 648 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 649 {
 650 }
 651
 652 /* this is called once with whichever end is closed last */
 653 static void pty_unix98_shutdown(struct tty_struct *tty)
 654 {
 655         devpts_kill_index(tty->driver_data, tty->index);
 656 }
 657
 658 static const struct tty_operations ptm_unix98_ops = {
 659         .lookup = ptm_unix98_lookup,
 660         .install = pty_unix98_install,
 661         .remove = pty_unix98_remove,
 662         .open = pty_open,
 663         .close = pty_close,
 664         .write = pty_write,
 665         .write_room = pty_write_room,
 666         .flush_buffer = pty_flush_buffer,
 667         .chars_in_buffer = pty_chars_in_buffer,
 668         .unthrottle = pty_unthrottle,
 669         .set_termios = pty_set_termios,
 670         .ioctl = pty_unix98_ioctl,
 671         .resize = pty_resize,
 672         .shutdown = pty_unix98_shutdown,
 673         .cleanup = pty_cleanup
 674 };
 675
 676 static const struct tty_operations pty_unix98_ops = {
 677         .lookup = pts_unix98_lookup,
 678         .install = pty_unix98_install,
 679         .remove = pty_unix98_remove,
 680         .open = pty_open,
 681         .close = pty_close,
 682         .write = pty_write,
 683         .write_room = pty_write_room,
 684         .flush_buffer = pty_flush_buffer,
 685         .chars_in_buffer = pty_chars_in_buffer,
 686         .unthrottle = pty_unthrottle,
 687         .set_termios = pty_set_termios,
 688         .start = pty_start,
 689         .stop = pty_stop,
 690         .shutdown = pty_unix98_shutdown,
 691         .cleanup = pty_cleanup,
 692 };
 693
 694 /**
 695  *      ptmx_open               -       open a unix 98 pty master
 696  *      @inode: inode of device file
 697  *      @filp: file pointer to tty
 698  *
 699  *      Allocate a unix98 pty master device from the ptmx driver.
 700  *
 701  *      Locking: tty_mutex protects the init_dev work. tty->count should
 702  *              protect the rest.
 703  *              allocated_ptys_lock handles the list of free pty numbers
 704  */
 705
 706 static int ptmx_open(struct inode *inode, struct file *filp)
 707 {
 708         struct tty_struct *tty;
 709         struct inode *slave_inode;
 710         int retval;
 711         int index;
 712
 713         nonseekable_open(inode, filp);
 714
 715         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 716         filp->f_mode |= FMODE_NONOTIFY;
 717
 718         retval = tty_alloc_file(filp);
 719         if (retval)
 720                 return retval;
 721
 722         /* find a device that is not in use. */
 723         mutex_lock(&devpts_mutex);
 724         index = devpts_new_index(inode);
 725         if (index < 0) {
 726                 retval = index;
 727                 mutex_unlock(&devpts_mutex);
 728                 goto err_file;
 729         }
 730
 731         mutex_unlock(&devpts_mutex);
 732
 733         mutex_lock(&tty_mutex);
 734         tty = tty_init_dev(ptm_driver, index);
 735
 736         if (IS_ERR(tty)) {
 737                 retval = PTR_ERR(tty);
 738                 goto out;
 739         }
 740
 741         /* The tty returned here is locked so we can safely
 742            drop the mutex */
 743         mutex_unlock(&tty_mutex);
 744
 745         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 746         tty->driver_data = inode;
 747
 748         tty_add_file(tty, filp);
 749
 750         slave_inode = devpts_pty_new(inode,
 751                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 752                         tty->link);
 753         if (IS_ERR(slave_inode)) {
 754                 retval = PTR_ERR(slave_inode);
 755                 goto err_release;
 756         }
 757         tty->link->driver_data = slave_inode;
 758
 759         retval = ptm_driver->ops->open(tty, filp);
 760         if (retval)
 761                 goto err_release;
 762
 763         tty_unlock(tty);
 764         return 0;
 765 err_release:
 766         tty_unlock(tty);
 767         tty_release(inode, filp);
 768         return retval;
 769 out:
 770         mutex_unlock(&tty_mutex);
 771         devpts_kill_index(inode, index);
 772 err_file:
 773         tty_free_file(filp);
 774         return retval;
 775 }
 776
 777 static struct file_operations ptmx_fops;
 778
 779 static void __init unix98_pty_init(void)
 780 {
 781         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 782                         TTY_DRIVER_RESET_TERMIOS |
 783                         TTY_DRIVER_REAL_RAW |
 784                         TTY_DRIVER_DYNAMIC_DEV |
 785                         TTY_DRIVER_DEVPTS_MEM |
 786                         TTY_DRIVER_DYNAMIC_ALLOC);
 787         if (IS_ERR(ptm_driver))
 788                 panic("Couldn't allocate Unix98 ptm driver");
 789         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 790                         TTY_DRIVER_RESET_TERMIOS |
 791                         TTY_DRIVER_REAL_RAW |
 792                         TTY_DRIVER_DYNAMIC_DEV |
 793                         TTY_DRIVER_DEVPTS_MEM |
 794                         TTY_DRIVER_DYNAMIC_ALLOC);
 795         if (IS_ERR(pts_driver))
 796                 panic("Couldn't allocate Unix98 pts driver");
 797
 798         ptm_driver->driver_name = "pty_master";
 799         ptm_driver->name = "ptm";
 800         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 801         ptm_driver->minor_start = 0;
 802         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 803         ptm_driver->subtype = PTY_TYPE_MASTER;
 804         ptm_driver->init_termios = tty_std_termios;
 805         ptm_driver->init_termios.c_iflag = 0;
 806         ptm_driver->init_termios.c_oflag = 0;
 807         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 808         ptm_driver->init_termios.c_lflag = 0;
 809         ptm_driver->init_termios.c_ispeed = 38400;
 810         ptm_driver->init_termios.c_ospeed = 38400;
 811         ptm_driver->other = pts_driver;
 812         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 813
 814         pts_driver->driver_name = "pty_slave";
 815         pts_driver->name = "pts";
 816         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 817         pts_driver->minor_start = 0;
 818         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 819         pts_driver->subtype = PTY_TYPE_SLAVE;
 820         pts_driver->init_termios = tty_std_termios;
 821         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 822         pts_driver->init_termios.c_ispeed = 38400;
 823         pts_driver->init_termios.c_ospeed = 38400;
 824         pts_driver->other = ptm_driver;
 825         tty_set_operations(pts_driver, &pty_unix98_ops);
 826
 827         if (tty_register_driver(ptm_driver))
 828                 panic("Couldn't register Unix98 ptm driver");
 829         if (tty_register_driver(pts_driver))
 830                 panic("Couldn't register Unix98 pts driver");
 831
 832         /* Now create the /dev/ptmx special device */
 833         tty_default_fops(&ptmx_fops);
 834         ptmx_fops.open = ptmx_open;
 835
 836         cdev_init(&ptmx_cdev, &ptmx_fops);
 837         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 838             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 839                 panic("Couldn't register /dev/ptmx driver");
 840         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 841 }
 842
 843 #else
 844 static inline void unix98_pty_init(void) { }
 845 #endif
 846
 847 static int __init pty_init(void)
 848 {
 849         legacy_pty_init();
 850         unix98_pty_init();
 851         return 0;
 852 }
 853 module_init(pty_init);