git.oblomov.eu Git - linux-2.6/blob - arch/um/drivers/line.c

   1 /*
   2  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/irqreturn.h"
   7 #include "linux/kd.h"
   8 #include "chan_kern.h"
   9 #include "irq_kern.h"
  10 #include "irq_user.h"
  11 #include "os.h"
  12
  13 #define LINE_BUFSIZE 4096
  14
  15 static irqreturn_t line_interrupt(int irq, void *data)
  16 {
  17         struct chan *chan = data;
  18         struct line *line = chan->line;
  19         struct tty_struct *tty = line->tty;
  20
  21         if (line)
  22                 chan_interrupt(&line->chan_list, &line->task, tty, irq);
  23         return IRQ_HANDLED;
  24 }
  25
  26 static void line_timer_cb(struct work_struct *work)
  27 {
  28         struct line *line = container_of(work, struct line, task.work);
  29
  30         if (!line->throttled)
  31                 chan_interrupt(&line->chan_list, &line->task, line->tty,
  32                                line->driver->read_irq);
  33 }
  34
  35 /*
  36  * Returns the free space inside the ring buffer of this line.
  37  *
  38  * Should be called while holding line->lock (this does not modify datas).
  39  */
  40 static int write_room(struct line *line)
  41 {
  42         int n;
  43
  44         if (line->buffer == NULL)
  45                 return LINE_BUFSIZE - 1;
  46
  47         /* This is for the case where the buffer is wrapped! */
  48         n = line->head - line->tail;
  49
  50         if (n <= 0)
  51                 n = LINE_BUFSIZE + n; /* The other case */
  52         return n - 1;
  53 }
  54
  55 int line_write_room(struct tty_struct *tty)
  56 {
  57         struct line *line = tty->driver_data;
  58         unsigned long flags;
  59         int room;
  60
  61         if (tty->stopped)
  62                 return 0;
  63
  64         spin_lock_irqsave(&line->lock, flags);
  65         room = write_room(line);
  66         spin_unlock_irqrestore(&line->lock, flags);
  67
  68         /*XXX: Warning to remove */
  69         if (0 == room)
  70                 printk(KERN_DEBUG "%s: %s: no room left in buffer\n",
  71                        __FUNCTION__,tty->name);
  72         return room;
  73 }
  74
  75 int line_chars_in_buffer(struct tty_struct *tty)
  76 {
  77         struct line *line = tty->driver_data;
  78         unsigned long flags;
  79         int ret;
  80
  81         spin_lock_irqsave(&line->lock, flags);
  82
  83         /*write_room subtracts 1 for the needed NULL, so we readd it.*/
  84         ret = LINE_BUFSIZE - (write_room(line) + 1);
  85         spin_unlock_irqrestore(&line->lock, flags);
  86
  87         return ret;
  88 }
  89
  90 /*
  91  * This copies the content of buf into the circular buffer associated with
  92  * this line.
  93  * The return value is the number of characters actually copied, i.e. the ones
  94  * for which there was space: this function is not supposed to ever flush out
  95  * the circular buffer.
  96  *
  97  * Must be called while holding line->lock!
  98  */
  99 static int buffer_data(struct line *line, const char *buf, int len)
 100 {
 101         int end, room;
 102
 103         if (line->buffer == NULL) {
 104                 line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
 105                 if (line->buffer == NULL) {
 106                         printk(KERN_ERR "buffer_data - atomic allocation "
 107                                "failed\n");
 108                         return 0;
 109                 }
 110                 line->head = line->buffer;
 111                 line->tail = line->buffer;
 112         }
 113
 114         room = write_room(line);
 115         len = (len > room) ? room : len;
 116
 117         end = line->buffer + LINE_BUFSIZE - line->tail;
 118
 119         if (len < end) {
 120                 memcpy(line->tail, buf, len);
 121                 line->tail += len;
 122         }
 123         else {
 124                 /* The circular buffer is wrapping */
 125                 memcpy(line->tail, buf, end);
 126                 buf += end;
 127                 memcpy(line->buffer, buf, len - end);
 128                 line->tail = line->buffer + len - end;
 129         }
 130
 131         return len;
 132 }
 133
 134 /*
 135  * Flushes the ring buffer to the output channels. That is, write_chan is
 136  * called, passing it line->head as buffer, and an appropriate count.
 137  *
 138  * On exit, returns 1 when the buffer is empty,
 139  * 0 when the buffer is not empty on exit,
 140  * and -errno when an error occurred.
 141  *
 142  * Must be called while holding line->lock!*/
 143 static int flush_buffer(struct line *line)
 144 {
 145         int n, count;
 146
 147         if ((line->buffer == NULL) || (line->head == line->tail))
 148                 return 1;
 149
 150         if (line->tail < line->head) {
 151                 /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
 152                 count = line->buffer + LINE_BUFSIZE - line->head;
 153
 154                 n = write_chan(&line->chan_list, line->head, count,
 155                                line->driver->write_irq);
 156                 if (n < 0)
 157                         return n;
 158                 if (n == count) {
 159                         /*
 160                          * We have flushed from ->head to buffer end, now we
 161                          * must flush only from the beginning to ->tail.
 162                          */
 163                         line->head = line->buffer;
 164                 } else {
 165                         line->head += n;
 166                         return 0;
 167                 }
 168         }
 169
 170         count = line->tail - line->head;
 171         n = write_chan(&line->chan_list, line->head, count,
 172                        line->driver->write_irq);
 173
 174         if (n < 0)
 175                 return n;
 176
 177         line->head += n;
 178         return line->head == line->tail;
 179 }
 180
 181 void line_flush_buffer(struct tty_struct *tty)
 182 {
 183         struct line *line = tty->driver_data;
 184         unsigned long flags;
 185         int err;
 186
 187         /*XXX: copied from line_write, verify if it is correct!*/
 188         if (tty->stopped)
 189                 return;
 190
 191         spin_lock_irqsave(&line->lock, flags);
 192         err = flush_buffer(line);
 193         spin_unlock_irqrestore(&line->lock, flags);
 194 }
 195
 196 /*
 197  * We map both ->flush_chars and ->put_char (which go in pair) onto
 198  * ->flush_buffer and ->write. Hope it's not that bad.
 199  */
 200 void line_flush_chars(struct tty_struct *tty)
 201 {
 202         line_flush_buffer(tty);
 203 }
 204
 205 void line_put_char(struct tty_struct *tty, unsigned char ch)
 206 {
 207         line_write(tty, &ch, sizeof(ch));
 208 }
 209
 210 int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
 211 {
 212         struct line *line = tty->driver_data;
 213         unsigned long flags;
 214         int n, ret = 0;
 215
 216         if (tty->stopped)
 217                 return 0;
 218
 219         spin_lock_irqsave(&line->lock, flags);
 220         if (line->head != line->tail)
 221                 ret = buffer_data(line, buf, len);
 222         else {
 223                 n = write_chan(&line->chan_list, buf, len,
 224                                line->driver->write_irq);
 225                 if (n < 0) {
 226                         ret = n;
 227                         goto out_up;
 228                 }
 229
 230                 len -= n;
 231                 ret += n;
 232                 if (len > 0)
 233                         ret += buffer_data(line, buf + n, len);
 234         }
 235 out_up:
 236         spin_unlock_irqrestore(&line->lock, flags);
 237         return ret;
 238 }
 239
 240 void line_set_termios(struct tty_struct *tty, struct ktermios * old)
 241 {
 242         /* nothing */
 243 }
 244
 245 static const struct {
 246         int  cmd;
 247         char *level;
 248         char *name;
 249 } tty_ioctls[] = {
 250         /* don't print these, they flood the log ... */
 251         { TCGETS,      NULL,       "TCGETS"      },
 252         { TCSETS,      NULL,       "TCSETS"      },
 253         { TCSETSW,     NULL,       "TCSETSW"     },
 254         { TCFLSH,      NULL,       "TCFLSH"      },
 255         { TCSBRK,      NULL,       "TCSBRK"      },
 256
 257         /* general tty stuff */
 258         { TCSETSF,     KERN_DEBUG, "TCSETSF"     },
 259         { TCGETA,      KERN_DEBUG, "TCGETA"      },
 260         { TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
 261         { TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
 262         { TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },
 263
 264         /* linux-specific ones */
 265         { TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
 266         { KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
 267         { KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
 268         { KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
 269 };
 270
 271 int line_ioctl(struct tty_struct *tty, struct file * file,
 272                unsigned int cmd, unsigned long arg)
 273 {
 274         int ret;
 275         int i;
 276
 277         ret = 0;
 278         switch(cmd) {
 279 #ifdef TIOCGETP
 280         case TIOCGETP:
 281         case TIOCSETP:
 282         case TIOCSETN:
 283 #endif
 284 #ifdef TIOCGETC
 285         case TIOCGETC:
 286         case TIOCSETC:
 287 #endif
 288 #ifdef TIOCGLTC
 289         case TIOCGLTC:
 290         case TIOCSLTC:
 291 #endif
 292         case TCGETS:
 293         case TCSETSF:
 294         case TCSETSW:
 295         case TCSETS:
 296         case TCGETA:
 297         case TCSETAF:
 298         case TCSETAW:
 299         case TCSETA:
 300         case TCXONC:
 301         case TCFLSH:
 302         case TIOCOUTQ:
 303         case TIOCINQ:
 304         case TIOCGLCKTRMIOS:
 305         case TIOCSLCKTRMIOS:
 306         case TIOCPKT:
 307         case TIOCGSOFTCAR:
 308         case TIOCSSOFTCAR:
 309                 return -ENOIOCTLCMD;
 310 #if 0
 311         case TCwhatever:
 312                 /* do something */
 313                 break;
 314 #endif
 315         default:
 316                 for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
 317                         if (cmd == tty_ioctls[i].cmd)
 318                                 break;
 319                 if (i == ARRAY_SIZE(tty_ioctls)) {
 320                         printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
 321                                __FUNCTION__, tty->name, cmd);
 322                 }
 323                 ret = -ENOIOCTLCMD;
 324                 break;
 325         }
 326         return ret;
 327 }
 328
 329 void line_throttle(struct tty_struct *tty)
 330 {
 331         struct line *line = tty->driver_data;
 332
 333         deactivate_chan(&line->chan_list, line->driver->read_irq);
 334         line->throttled = 1;
 335 }
 336
 337 void line_unthrottle(struct tty_struct *tty)
 338 {
 339         struct line *line = tty->driver_data;
 340
 341         line->throttled = 0;
 342         chan_interrupt(&line->chan_list, &line->task, tty,
 343                        line->driver->read_irq);
 344
 345         /*
 346          * Maybe there is enough stuff pending that calling the interrupt
 347          * throttles us again.  In this case, line->throttled will be 1
 348          * again and we shouldn't turn the interrupt back on.
 349          */
 350         if (!line->throttled)
 351                 reactivate_chan(&line->chan_list, line->driver->read_irq);
 352 }
 353
 354 static irqreturn_t line_write_interrupt(int irq, void *data)
 355 {
 356         struct chan *chan = data;
 357         struct line *line = chan->line;
 358         struct tty_struct *tty = line->tty;
 359         int err;
 360
 361         /*
 362          * Interrupts are disabled here because we registered the interrupt with
 363          * IRQF_DISABLED (see line_setup_irq).
 364          */
 365
 366         spin_lock(&line->lock);
 367         err = flush_buffer(line);
 368         if (err == 0) {
 369                 return IRQ_NONE;
 370         } else if (err < 0) {
 371                 line->head = line->buffer;
 372                 line->tail = line->buffer;
 373         }
 374         spin_unlock(&line->lock);
 375
 376         if (tty == NULL)
 377                 return IRQ_NONE;
 378
 379         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
 380            (tty->ldisc.write_wakeup != NULL))
 381                 (tty->ldisc.write_wakeup)(tty);
 382
 383         /*
 384          * BLOCKING mode
 385          * In blocking mode, everything sleeps on tty->write_wait.
 386          * Sleeping in the console driver would break non-blocking
 387          * writes.
 388          */
 389
 390         if (waitqueue_active(&tty->write_wait))
 391                 wake_up_interruptible(&tty->write_wait);
 392         return IRQ_HANDLED;
 393 }
 394
 395 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
 396 {
 397         const struct line_driver *driver = line->driver;
 398         int err = 0, flags = IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM;
 399
 400         if (input)
 401                 err = um_request_irq(driver->read_irq, fd, IRQ_READ,
 402                                        line_interrupt, flags,
 403                                        driver->read_irq_name, data);
 404         if (err)
 405                 return err;
 406         if (output)
 407                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 408                                         line_write_interrupt, flags,
 409                                         driver->write_irq_name, data);
 410         line->have_irq = 1;
 411         return err;
 412 }
 413
 414 /*
 415  * Normally, a driver like this can rely mostly on the tty layer
 416  * locking, particularly when it comes to the driver structure.
 417  * However, in this case, mconsole requests can come in "from the
 418  * side", and race with opens and closes.
 419  *
 420  * mconsole config requests will want to be sure the device isn't in
 421  * use, and get_config, open, and close will want a stable
 422  * configuration.  The checking and modification of the configuration
 423  * is done under a spinlock.  Checking whether the device is in use is
 424  * line->tty->count > 1, also under the spinlock.
 425  *
 426  * tty->count serves to decide whether the device should be enabled or
 427  * disabled on the host.  If it's equal to 1, then we are doing the
 428  * first open or last close.  Otherwise, open and close just return.
 429  */
 430
 431 int line_open(struct line *lines, struct tty_struct *tty)
 432 {
 433         struct line *line = &lines[tty->index];
 434         int err = -ENODEV;
 435
 436         spin_lock(&line->count_lock);
 437         if (!line->valid)
 438                 goto out_unlock;
 439
 440         err = 0;
 441         if (tty->count > 1)
 442                 goto out_unlock;
 443
 444         spin_unlock(&line->count_lock);
 445
 446         tty->driver_data = line;
 447         line->tty = tty;
 448
 449         err = enable_chan(line);
 450         if (err)
 451                 return err;
 452
 453         INIT_DELAYED_WORK(&line->task, line_timer_cb);
 454
 455         if (!line->sigio) {
 456                 chan_enable_winch(&line->chan_list, tty);
 457                 line->sigio = 1;
 458         }
 459
 460         chan_window_size(&line->chan_list, &tty->winsize.ws_row,
 461                          &tty->winsize.ws_col);
 462
 463         return err;
 464
 465 out_unlock:
 466         spin_unlock(&line->count_lock);
 467         return err;
 468 }
 469
 470 static void unregister_winch(struct tty_struct *tty);
 471
 472 void line_close(struct tty_struct *tty, struct file * filp)
 473 {
 474         struct line *line = tty->driver_data;
 475
 476         /*
 477          * If line_open fails (and tty->driver_data is never set),
 478          * tty_open will call line_close.  So just return in this case.
 479          */
 480         if (line == NULL)
 481                 return;
 482
 483         /* We ignore the error anyway! */
 484         flush_buffer(line);
 485
 486         spin_lock(&line->count_lock);
 487         if (!line->valid)
 488                 goto out_unlock;
 489
 490         if (tty->count > 1)
 491                 goto out_unlock;
 492
 493         spin_unlock(&line->count_lock);
 494
 495         line->tty = NULL;
 496         tty->driver_data = NULL;
 497
 498         if (line->sigio) {
 499                 unregister_winch(tty);
 500                 line->sigio = 0;
 501         }
 502
 503         return;
 504
 505 out_unlock:
 506         spin_unlock(&line->count_lock);
 507 }
 508
 509 void close_lines(struct line *lines, int nlines)
 510 {
 511         int i;
 512
 513         for(i = 0; i < nlines; i++)
 514                 close_chan(&lines[i].chan_list, 0);
 515 }
 516
 517 static int setup_one_line(struct line *lines, int n, char *init, int init_prio,
 518                           char **error_out)
 519 {
 520         struct line *line = &lines[n];
 521         int err = -EINVAL;
 522
 523         spin_lock(&line->count_lock);
 524
 525         if (line->tty != NULL) {
 526                 *error_out = "Device is already open";
 527                 goto out;
 528         }
 529
 530         if (line->init_pri <= init_prio) {
 531                 line->init_pri = init_prio;
 532                 if (!strcmp(init, "none"))
 533                         line->valid = 0;
 534                 else {
 535                         line->init_str = init;
 536                         line->valid = 1;
 537                 }
 538         }
 539         err = 0;
 540 out:
 541         spin_unlock(&line->count_lock);
 542         return err;
 543 }
 544
 545 /*
 546  * Common setup code for both startup command line and mconsole initialization.
 547  * @lines contains the array (of size @num) to modify;
 548  * @init is the setup string;
 549  * @error_out is an error string in the case of failure;
 550  */
 551
 552 int line_setup(struct line *lines, unsigned int num, char *init,
 553                char **error_out)
 554 {
 555         int i, n, err;
 556         char *end;
 557
 558         if (*init == '=') {
 559                 /*
 560                  * We said con=/ssl= instead of con#=, so we are configuring all
 561                  * consoles at once.
 562                  */
 563                 n = -1;
 564         }
 565         else {
 566                 n = simple_strtoul(init, &end, 0);
 567                 if (*end != '=') {
 568                         *error_out = "Couldn't parse device number";
 569                         return -EINVAL;
 570                 }
 571                 init = end;
 572         }
 573         init++;
 574
 575         if (n >= (signed int) num) {
 576                 *error_out = "Device number out of range";
 577                 return -EINVAL;
 578         }
 579         else if (n >= 0) {
 580                 err = setup_one_line(lines, n, init, INIT_ONE, error_out);
 581                 if (err)
 582                         return err;
 583         }
 584         else {
 585                 for(i = 0; i < num; i++) {
 586                         err = setup_one_line(lines, i, init, INIT_ALL,
 587                                              error_out);
 588                         if (err)
 589                                 return err;
 590                 }
 591         }
 592         return n == -1 ? num : n;
 593 }
 594
 595 int line_config(struct line *lines, unsigned int num, char *str,
 596                 const struct chan_opts *opts, char **error_out)
 597 {
 598         struct line *line;
 599         char *new;
 600         int n;
 601
 602         if (*str == '=') {
 603                 *error_out = "Can't configure all devices from mconsole";
 604                 return -EINVAL;
 605         }
 606
 607         new = kstrdup(str, GFP_KERNEL);
 608         if (new == NULL) {
 609                 *error_out = "Failed to allocate memory";
 610                 return -ENOMEM;
 611         }
 612         n = line_setup(lines, num, new, error_out);
 613         if (n < 0)
 614                 return n;
 615
 616         line = &lines[n];
 617         return parse_chan_pair(line->init_str, line, n, opts, error_out);
 618 }
 619
 620 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 621                     int size, char **error_out)
 622 {
 623         struct line *line;
 624         char *end;
 625         int dev, n = 0;
 626
 627         dev = simple_strtoul(name, &end, 0);
 628         if ((*end != '\0') || (end == name)) {
 629                 *error_out = "line_get_config failed to parse device number";
 630                 return 0;
 631         }
 632
 633         if ((dev < 0) || (dev >= num)) {
 634                 *error_out = "device number out of range";
 635                 return 0;
 636         }
 637
 638         line = &lines[dev];
 639
 640         spin_lock(&line->count_lock);
 641         if (!line->valid)
 642                 CONFIG_CHUNK(str, size, n, "none", 1);
 643         else if (line->tty == NULL)
 644                 CONFIG_CHUNK(str, size, n, line->init_str, 1);
 645         else n = chan_config_string(&line->chan_list, str, size, error_out);
 646         spin_unlock(&line->count_lock);
 647
 648         return n;
 649 }
 650
 651 int line_id(char **str, int *start_out, int *end_out)
 652 {
 653         char *end;
 654         int n;
 655
 656         n = simple_strtoul(*str, &end, 0);
 657         if ((*end != '\0') || (end == *str))
 658                 return -1;
 659
 660         *str = end;
 661         *start_out = n;
 662         *end_out = n;
 663         return n;
 664 }
 665
 666 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 667 {
 668         int err;
 669         char config[sizeof("conxxxx=none\0")];
 670
 671         sprintf(config, "%d=none", n);
 672         err = line_setup(lines, num, config, error_out);
 673         if (err >= 0)
 674                 err = 0;
 675         return err;
 676 }
 677
 678 struct tty_driver *register_lines(struct line_driver *line_driver,
 679                                   const struct tty_operations *ops,
 680                                   struct line *lines, int nlines)
 681 {
 682         int i;
 683         struct tty_driver *driver = alloc_tty_driver(nlines);
 684
 685         if (!driver)
 686                 return NULL;
 687
 688         driver->driver_name = line_driver->name;
 689         driver->name = line_driver->device_name;
 690         driver->major = line_driver->major;
 691         driver->minor_start = line_driver->minor_start;
 692         driver->type = line_driver->type;
 693         driver->subtype = line_driver->subtype;
 694         driver->flags = TTY_DRIVER_REAL_RAW;
 695         driver->init_termios = tty_std_termios;
 696         tty_set_operations(driver, ops);
 697
 698         if (tty_register_driver(driver)) {
 699                 printk(KERN_ERR "register_lines : can't register %s driver\n",
 700                        line_driver->name);
 701                 put_tty_driver(driver);
 702                 return NULL;
 703         }
 704
 705         for(i = 0; i < nlines; i++) {
 706                 if (!lines[i].valid)
 707                         tty_unregister_device(driver, i);
 708         }
 709
 710         mconsole_register_dev(&line_driver->mc);
 711         return driver;
 712 }
 713
 714 static DEFINE_SPINLOCK(winch_handler_lock);
 715 static LIST_HEAD(winch_handlers);
 716
 717 void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
 718 {
 719         struct line *line;
 720         char *error;
 721         int i;
 722
 723         for(i = 0; i < nlines; i++) {
 724                 line = &lines[i];
 725                 INIT_LIST_HEAD(&line->chan_list);
 726
 727                 if (line->init_str == NULL)
 728                         continue;
 729
 730                 line->init_str = kstrdup(line->init_str, GFP_KERNEL);
 731                 if (line->init_str == NULL)
 732                         printk(KERN_ERR "lines_init - kstrdup returned NULL\n");
 733
 734                 if (parse_chan_pair(line->init_str, line, i, opts, &error)) {
 735                         printk(KERN_ERR "parse_chan_pair failed for "
 736                                "device %d : %s\n", i, error);
 737                         line->valid = 0;
 738                 }
 739         }
 740 }
 741
 742 struct winch {
 743         struct list_head list;
 744         int fd;
 745         int tty_fd;
 746         int pid;
 747         struct tty_struct *tty;
 748         unsigned long stack;
 749 };
 750
 751 static void free_winch(struct winch *winch, int free_irq_ok)
 752 {
 753         list_del(&winch->list);
 754
 755         if (winch->pid != -1)
 756                 os_kill_process(winch->pid, 1);
 757         if (winch->fd != -1)
 758                 os_close_file(winch->fd);
 759         if (winch->stack != 0)
 760                 free_stack(winch->stack, 0);
 761         if (free_irq_ok)
 762                 free_irq(WINCH_IRQ, winch);
 763         kfree(winch);
 764 }
 765
 766 static irqreturn_t winch_interrupt(int irq, void *data)
 767 {
 768         struct winch *winch = data;
 769         struct tty_struct *tty;
 770         struct line *line;
 771         int err;
 772         char c;
 773
 774         if (winch->fd != -1) {
 775                 err = generic_read(winch->fd, &c, NULL);
 776                 if (err < 0) {
 777                         if (err != -EAGAIN) {
 778                                 printk(KERN_ERR "winch_interrupt : "
 779                                        "read failed, errno = %d\n", -err);
 780                                 printk(KERN_ERR "fd %d is losing SIGWINCH "
 781                                        "support\n", winch->tty_fd);
 782                                 free_winch(winch, 0);
 783                                 return IRQ_HANDLED;
 784                         }
 785                         goto out;
 786                 }
 787         }
 788         tty = winch->tty;
 789         if (tty != NULL) {
 790                 line = tty->driver_data;
 791                 chan_window_size(&line->chan_list, &tty->winsize.ws_row,
 792                                  &tty->winsize.ws_col);
 793                 kill_pgrp(tty->pgrp, SIGWINCH, 1);
 794         }
 795  out:
 796         if (winch->fd != -1)
 797                 reactivate_fd(winch->fd, WINCH_IRQ);
 798         return IRQ_HANDLED;
 799 }
 800
 801 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
 802                         unsigned long stack)
 803 {
 804         struct winch *winch;
 805
 806         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
 807         if (winch == NULL) {
 808                 printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
 809                 goto cleanup;
 810         }
 811
 812         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
 813                                    .fd          = fd,
 814                                    .tty_fd      = tty_fd,
 815                                    .pid         = pid,
 816                                    .tty         = tty,
 817                                    .stack       = stack });
 818
 819         if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 820                            IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 821                            "winch", winch) < 0) {
 822                 printk(KERN_ERR "register_winch_irq - failed to register "
 823                        "IRQ\n");
 824                 goto out_free;
 825         }
 826
 827         spin_lock(&winch_handler_lock);
 828         list_add(&winch->list, &winch_handlers);
 829         spin_unlock(&winch_handler_lock);
 830
 831         return;
 832
 833  out_free:
 834         kfree(winch);
 835  cleanup:
 836         os_kill_process(pid, 1);
 837         os_close_file(fd);
 838         if (stack != 0)
 839                 free_stack(stack, 0);
 840 }
 841
 842 static void unregister_winch(struct tty_struct *tty)
 843 {
 844         struct list_head *ele;
 845         struct winch *winch;
 846
 847         spin_lock(&winch_handler_lock);
 848
 849         list_for_each(ele, &winch_handlers) {
 850                 winch = list_entry(ele, struct winch, list);
 851                 if (winch->tty == tty) {
 852                         free_winch(winch, 1);
 853                         break;
 854                 }
 855         }
 856         spin_unlock(&winch_handler_lock);
 857 }
 858
 859 static void winch_cleanup(void)
 860 {
 861         struct list_head *ele, *next;
 862         struct winch *winch;
 863
 864         spin_lock(&winch_handler_lock);
 865
 866         list_for_each_safe(ele, next, &winch_handlers) {
 867                 winch = list_entry(ele, struct winch, list);
 868                 free_winch(winch, 1);
 869         }
 870
 871         spin_unlock(&winch_handler_lock);
 872 }
 873 __uml_exitcall(winch_cleanup);
 874
 875 char *add_xterm_umid(char *base)
 876 {
 877         char *umid, *title;
 878         int len;
 879
 880         umid = get_umid();
 881         if (*umid == '\0')
 882                 return base;
 883
 884         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 885         title = kmalloc(len, GFP_KERNEL);
 886         if (title == NULL) {
 887                 printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
 888                 return base;
 889         }
 890
 891         snprintf(title, len, "%s (%s)", base, umid);
 892         return title;
 893 }