SAFE public projects git trees. - safe/jmp/linux-2.6/blob - arch/um/drivers/line.c

   1 /*
   2  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/sched.h"
   7 #include "linux/slab.h"
   8 #include "linux/list.h"
   9 #include "linux/kd.h"
  10 #include "linux/interrupt.h"
  11 #include "linux/devfs_fs_kernel.h"
  12 #include "asm/uaccess.h"
  13 #include "chan_kern.h"
  14 #include "irq_user.h"
  15 #include "line.h"
  16 #include "kern.h"
  17 #include "user_util.h"
  18 #include "kern_util.h"
  19 #include "os.h"
  20 #include "irq_kern.h"
  21
  22 #define LINE_BUFSIZE 4096
  23
  24 static irqreturn_t line_interrupt(int irq, void *data, struct pt_regs *unused)
  25 {
  26         struct tty_struct *tty = data;
  27         struct line *line = tty->driver_data;
  28
  29         if (line)
  30                 chan_interrupt(&line->chan_list, &line->task, tty, irq);
  31         return IRQ_HANDLED;
  32 }
  33
  34 static void line_timer_cb(void *arg)
  35 {
  36         struct tty_struct *tty = arg;
  37         struct line *line = tty->driver_data;
  38
  39         line_interrupt(line->driver->read_irq, arg, NULL);
  40 }
  41
  42 /* Returns the free space inside the ring buffer of this line.
  43  *
  44  * Should be called while holding line->lock (this does not modify datas).
  45  */
  46 static int write_room(struct line *line)
  47 {
  48         int n;
  49
  50         if (line->buffer == NULL)
  51                 return LINE_BUFSIZE - 1;
  52
  53         /* This is for the case where the buffer is wrapped! */
  54         n = line->head - line->tail;
  55
  56         if (n <= 0)
  57                 n = LINE_BUFSIZE + n; /* The other case */
  58         return n - 1;
  59 }
  60
  61 int line_write_room(struct tty_struct *tty)
  62 {
  63         struct line *line = tty->driver_data;
  64         unsigned long flags;
  65         int room;
  66
  67         if (tty->stopped)
  68                 return 0;
  69
  70         spin_lock_irqsave(&line->lock, flags);
  71         room = write_room(line);
  72         spin_unlock_irqrestore(&line->lock, flags);
  73
  74         /*XXX: Warning to remove */
  75         if (0 == room)
  76                 printk(KERN_DEBUG "%s: %s: no room left in buffer\n",
  77                        __FUNCTION__,tty->name);
  78         return room;
  79 }
  80
  81 int line_chars_in_buffer(struct tty_struct *tty)
  82 {
  83         struct line *line = tty->driver_data;
  84         unsigned long flags;
  85         int ret;
  86
  87         spin_lock_irqsave(&line->lock, flags);
  88
  89         /*write_room subtracts 1 for the needed NULL, so we readd it.*/
  90         ret = LINE_BUFSIZE - (write_room(line) + 1);
  91         spin_unlock_irqrestore(&line->lock, flags);
  92
  93         return ret;
  94 }
  95
  96 /*
  97  * This copies the content of buf into the circular buffer associated with
  98  * this line.
  99  * The return value is the number of characters actually copied, i.e. the ones
 100  * for which there was space: this function is not supposed to ever flush out
 101  * the circular buffer.
 102  *
 103  * Must be called while holding line->lock!
 104  */
 105 static int buffer_data(struct line *line, const char *buf, int len)
 106 {
 107         int end, room;
 108
 109         if(line->buffer == NULL){
 110                 line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
 111                 if (line->buffer == NULL) {
 112                         printk("buffer_data - atomic allocation failed\n");
 113                         return(0);
 114                 }
 115                 line->head = line->buffer;
 116                 line->tail = line->buffer;
 117         }
 118
 119         room = write_room(line);
 120         len = (len > room) ? room : len;
 121
 122         end = line->buffer + LINE_BUFSIZE - line->tail;
 123
 124         if (len < end){
 125                 memcpy(line->tail, buf, len);
 126                 line->tail += len;
 127         }
 128         else {
 129                 /* The circular buffer is wrapping */
 130                 memcpy(line->tail, buf, end);
 131                 buf += end;
 132                 memcpy(line->buffer, buf, len - end);
 133                 line->tail = line->buffer + len - end;
 134         }
 135
 136         return len;
 137 }
 138
 139 /*
 140  * Flushes the ring buffer to the output channels. That is, write_chan is
 141  * called, passing it line->head as buffer, and an appropriate count.
 142  *
 143  * On exit, returns 1 when the buffer is empty,
 144  * 0 when the buffer is not empty on exit,
 145  * and -errno when an error occurred.
 146  *
 147  * Must be called while holding line->lock!*/
 148 static int flush_buffer(struct line *line)
 149 {
 150         int n, count;
 151
 152         if ((line->buffer == NULL) || (line->head == line->tail))
 153                 return 1;
 154
 155         if (line->tail < line->head) {
 156                 /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
 157                 count = line->buffer + LINE_BUFSIZE - line->head;
 158
 159                 n = write_chan(&line->chan_list, line->head, count,
 160                                line->driver->write_irq);
 161                 if (n < 0)
 162                         return n;
 163                 if (n == count) {
 164                         /* We have flushed from ->head to buffer end, now we
 165                          * must flush only from the beginning to ->tail.*/
 166                         line->head = line->buffer;
 167                 } else {
 168                         line->head += n;
 169                         return 0;
 170                 }
 171         }
 172
 173         count = line->tail - line->head;
 174         n = write_chan(&line->chan_list, line->head, count,
 175                        line->driver->write_irq);
 176
 177         if(n < 0)
 178                 return n;
 179
 180         line->head += n;
 181         return line->head == line->tail;
 182 }
 183
 184 void line_flush_buffer(struct tty_struct *tty)
 185 {
 186         struct line *line = tty->driver_data;
 187         unsigned long flags;
 188         int err;
 189
 190         /*XXX: copied from line_write, verify if it is correct!*/
 191         if(tty->stopped)
 192                 return;
 193                 //return 0;
 194
 195         spin_lock_irqsave(&line->lock, flags);
 196         err = flush_buffer(line);
 197         /*if (err == 1)
 198                 err = 0;*/
 199         spin_unlock_irqrestore(&line->lock, flags);
 200         //return err;
 201 }
 202
 203 /* We map both ->flush_chars and ->put_char (which go in pair) onto ->flush_buffer
 204  * and ->write. Hope it's not that bad.*/
 205 void line_flush_chars(struct tty_struct *tty)
 206 {
 207         line_flush_buffer(tty);
 208 }
 209
 210 void line_put_char(struct tty_struct *tty, unsigned char ch)
 211 {
 212         line_write(tty, &ch, sizeof(ch));
 213 }
 214
 215 int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
 216 {
 217         struct line *line = tty->driver_data;
 218         unsigned long flags;
 219         int n, err, ret = 0;
 220
 221         if(tty->stopped)
 222                 return 0;
 223
 224         spin_lock_irqsave(&line->lock, flags);
 225         if (line->head != line->tail) {
 226                 ret = buffer_data(line, buf, len);
 227                 err = flush_buffer(line);
 228                 if (err <= 0 && (err != -EAGAIN || !ret))
 229                         ret = err;
 230         } else {
 231                 n = write_chan(&line->chan_list, buf, len,
 232                                line->driver->write_irq);
 233                 if (n < 0) {
 234                         ret = n;
 235                         goto out_up;
 236                 }
 237
 238                 len -= n;
 239                 ret += n;
 240                 if (len > 0)
 241                         ret += buffer_data(line, buf + n, len);
 242         }
 243 out_up:
 244         spin_unlock_irqrestore(&line->lock, flags);
 245         return ret;
 246 }
 247
 248 void line_set_termios(struct tty_struct *tty, struct termios * old)
 249 {
 250         /* nothing */
 251 }
 252
 253 static struct {
 254         int  cmd;
 255         char *level;
 256         char *name;
 257 } tty_ioctls[] = {
 258         /* don't print these, they flood the log ... */
 259         { TCGETS,      NULL,       "TCGETS"      },
 260         { TCSETS,      NULL,       "TCSETS"      },
 261         { TCSETSW,     NULL,       "TCSETSW"     },
 262         { TCFLSH,      NULL,       "TCFLSH"      },
 263         { TCSBRK,      NULL,       "TCSBRK"      },
 264
 265         /* general tty stuff */
 266         { TCSETSF,     KERN_DEBUG, "TCSETSF"     },
 267         { TCGETA,      KERN_DEBUG, "TCGETA"      },
 268         { TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
 269         { TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
 270         { TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },
 271
 272         /* linux-specific ones */
 273         { TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
 274         { KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
 275         { KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
 276         { KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
 277 };
 278
 279 int line_ioctl(struct tty_struct *tty, struct file * file,
 280                unsigned int cmd, unsigned long arg)
 281 {
 282         int ret;
 283         int i;
 284
 285         ret = 0;
 286         switch(cmd) {
 287 #ifdef TIOCGETP
 288         case TIOCGETP:
 289         case TIOCSETP:
 290         case TIOCSETN:
 291 #endif
 292 #ifdef TIOCGETC
 293         case TIOCGETC:
 294         case TIOCSETC:
 295 #endif
 296 #ifdef TIOCGLTC
 297         case TIOCGLTC:
 298         case TIOCSLTC:
 299 #endif
 300         case TCGETS:
 301         case TCSETSF:
 302         case TCSETSW:
 303         case TCSETS:
 304         case TCGETA:
 305         case TCSETAF:
 306         case TCSETAW:
 307         case TCSETA:
 308         case TCXONC:
 309         case TCFLSH:
 310         case TIOCOUTQ:
 311         case TIOCINQ:
 312         case TIOCGLCKTRMIOS:
 313         case TIOCSLCKTRMIOS:
 314         case TIOCPKT:
 315         case TIOCGSOFTCAR:
 316         case TIOCSSOFTCAR:
 317                 return -ENOIOCTLCMD;
 318 #if 0
 319         case TCwhatever:
 320                 /* do something */
 321                 break;
 322 #endif
 323         default:
 324                 for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
 325                         if (cmd == tty_ioctls[i].cmd)
 326                                 break;
 327                 if (i < ARRAY_SIZE(tty_ioctls)) {
 328                         if (NULL != tty_ioctls[i].level)
 329                                 printk("%s%s: %s: ioctl %s called\n",
 330                                        tty_ioctls[i].level, __FUNCTION__,
 331                                        tty->name, tty_ioctls[i].name);
 332                 } else {
 333                         printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
 334                                __FUNCTION__, tty->name, cmd);
 335                 }
 336                 ret = -ENOIOCTLCMD;
 337                 break;
 338         }
 339         return ret;
 340 }
 341
 342 static irqreturn_t line_write_interrupt(int irq, void *data,
 343                                         struct pt_regs *unused)
 344 {
 345         struct tty_struct *tty = data;
 346         struct line *line = tty->driver_data;
 347         int err;
 348
 349         /* Interrupts are enabled here because we registered the interrupt with
 350          * SA_INTERRUPT (see line_setup_irq).*/
 351
 352         spin_lock_irq(&line->lock);
 353         err = flush_buffer(line);
 354         if (err == 0) {
 355                 return IRQ_NONE;
 356         } else if(err < 0) {
 357                 line->head = line->buffer;
 358                 line->tail = line->buffer;
 359         }
 360         spin_unlock_irq(&line->lock);
 361
 362         if(tty == NULL)
 363                 return IRQ_NONE;
 364
 365         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
 366            (tty->ldisc.write_wakeup != NULL))
 367                 (tty->ldisc.write_wakeup)(tty);
 368
 369         /* BLOCKING mode
 370          * In blocking mode, everything sleeps on tty->write_wait.
 371          * Sleeping in the console driver would break non-blocking
 372          * writes.
 373          */
 374
 375         if (waitqueue_active(&tty->write_wait))
 376                 wake_up_interruptible(&tty->write_wait);
 377         return IRQ_HANDLED;
 378 }
 379
 380 int line_setup_irq(int fd, int input, int output, struct tty_struct *tty)
 381 {
 382         struct line *line = tty->driver_data;
 383         struct line_driver *driver = line->driver;
 384         int err = 0, flags = SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM;
 385
 386         if (input)
 387                 err = um_request_irq(driver->read_irq, fd, IRQ_READ,
 388                                        line_interrupt, flags,
 389                                        driver->read_irq_name, tty);
 390         if (err)
 391                 return err;
 392         if (output)
 393                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 394                                         line_write_interrupt, flags,
 395                                         driver->write_irq_name, tty);
 396         line->have_irq = 1;
 397         return err;
 398 }
 399
 400 void line_disable(struct tty_struct *tty, int current_irq)
 401 {
 402         struct line *line = tty->driver_data;
 403
 404         if(!line->have_irq)
 405                 return;
 406
 407         if(line->driver->read_irq == current_irq)
 408                 free_irq_later(line->driver->read_irq, tty);
 409         else {
 410                 free_irq(line->driver->read_irq, tty);
 411         }
 412
 413         if(line->driver->write_irq == current_irq)
 414                 free_irq_later(line->driver->write_irq, tty);
 415         else {
 416                 free_irq(line->driver->write_irq, tty);
 417         }
 418
 419         line->have_irq = 0;
 420 }
 421
 422 int line_open(struct line *lines, struct tty_struct *tty,
 423               struct chan_opts *opts)
 424 {
 425         struct line *line;
 426         int err = 0;
 427
 428         line = &lines[tty->index];
 429         tty->driver_data = line;
 430
 431         /* The IRQ which takes this lock is not yet enabled and won't be run
 432          * before the end, so we don't need to use spin_lock_irq.*/
 433         spin_lock(&line->lock);
 434         if (tty->count == 1) {
 435                 if (!line->valid) {
 436                         err = -ENODEV;
 437                         goto out;
 438                 }
 439                 if (list_empty(&line->chan_list)) {
 440                         err = parse_chan_pair(line->init_str, &line->chan_list,
 441                                               tty->index, opts);
 442                         if(err) goto out;
 443                         err = open_chan(&line->chan_list);
 444                         if(err) goto out;
 445                 }
 446                 /* Here the interrupt is registered.*/
 447                 enable_chan(&line->chan_list, tty);
 448                 INIT_WORK(&line->task, line_timer_cb, tty);
 449         }
 450
 451         if(!line->sigio){
 452                 chan_enable_winch(&line->chan_list, tty);
 453                 line->sigio = 1;
 454         }
 455         chan_window_size(&line->chan_list, &tty->winsize.ws_row,
 456                          &tty->winsize.ws_col);
 457         line->count++;
 458
 459 out:
 460         spin_unlock(&line->lock);
 461         return err;
 462 }
 463
 464 static void unregister_winch(struct tty_struct *tty);
 465
 466 void line_close(struct tty_struct *tty, struct file * filp)
 467 {
 468         struct line *line = tty->driver_data;
 469
 470         /* XXX: I assume this should be called in process context, not with
 471          *  interrupts disabled!
 472          */
 473         spin_lock_irq(&line->lock);
 474
 475         /* We ignore the error anyway! */
 476         flush_buffer(line);
 477
 478         line->count--;
 479         if (tty->count == 1) {
 480                 line_disable(tty, -1);
 481                 tty->driver_data = NULL;
 482         }
 483
 484         if((line->count == 0) && line->sigio){
 485                 unregister_winch(tty);
 486                 line->sigio = 0;
 487         }
 488
 489         spin_unlock_irq(&line->lock);
 490 }
 491
 492 void close_lines(struct line *lines, int nlines)
 493 {
 494         int i;
 495
 496         for(i = 0; i < nlines; i++)
 497                 close_chan(&lines[i].chan_list);
 498 }
 499
 500 /* Common setup code for both startup command line and mconsole initialization.
 501  * @lines contains the the array (of size @num) to modify;
 502  * @init is the setup string;
 503  */
 504
 505 int line_setup(struct line *lines, unsigned int num, char *init)
 506 {
 507         int i, n;
 508         char *end;
 509
 510         if(*init == '=') {
 511                 /* We said con=/ssl= instead of con#=, so we are configuring all
 512                  * consoles at once.*/
 513                 n = -1;
 514         }
 515         else {
 516                 n = simple_strtoul(init, &end, 0);
 517                 if(*end != '='){
 518                         printk(KERN_ERR "line_setup failed to parse \"%s\"\n",
 519                                init);
 520                         return 0;
 521                 }
 522                 init = end;
 523         }
 524         init++;
 525
 526         if (n >= (signed int) num) {
 527                 printk("line_setup - %d out of range ((0 ... %d) allowed)\n",
 528                        n, num - 1);
 529                 return 0;
 530         }
 531         else if (n >= 0){
 532                 if (lines[n].count > 0) {
 533                         printk("line_setup - device %d is open\n", n);
 534                         return 0;
 535                 }
 536                 if (lines[n].init_pri <= INIT_ONE){
 537                         lines[n].init_pri = INIT_ONE;
 538                         if (!strcmp(init, "none"))
 539                                 lines[n].valid = 0;
 540                         else {
 541                                 lines[n].init_str = init;
 542                                 lines[n].valid = 1;
 543                         }
 544                 }
 545         }
 546         else {
 547                 for(i = 0; i < num; i++){
 548                         if(lines[i].init_pri <= INIT_ALL){
 549                                 lines[i].init_pri = INIT_ALL;
 550                                 if(!strcmp(init, "none")) lines[i].valid = 0;
 551                                 else {
 552                                         lines[i].init_str = init;
 553                                         lines[i].valid = 1;
 554                                 }
 555                         }
 556                 }
 557         }
 558         return 1;
 559 }
 560
 561 int line_config(struct line *lines, unsigned int num, char *str)
 562 {
 563         char *new;
 564
 565         if(*str == '='){
 566                 printk("line_config - can't configure all devices from "
 567                        "mconsole\n");
 568                 return 1;
 569         }
 570
 571         new = kstrdup(str, GFP_KERNEL);
 572         if(new == NULL){
 573                 printk("line_config - kstrdup failed\n");
 574                 return -ENOMEM;
 575         }
 576         return !line_setup(lines, num, new);
 577 }
 578
 579 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 580                     int size, char **error_out)
 581 {
 582         struct line *line;
 583         char *end;
 584         int dev, n = 0;
 585
 586         dev = simple_strtoul(name, &end, 0);
 587         if((*end != '\0') || (end == name)){
 588                 *error_out = "line_get_config failed to parse device number";
 589                 return 0;
 590         }
 591
 592         if((dev < 0) || (dev >= num)){
 593                 *error_out = "device number out of range";
 594                 return 0;
 595         }
 596
 597         line = &lines[dev];
 598
 599         spin_lock(&line->lock);
 600         if(!line->valid)
 601                 CONFIG_CHUNK(str, size, n, "none", 1);
 602         else if(line->count == 0)
 603                 CONFIG_CHUNK(str, size, n, line->init_str, 1);
 604         else n = chan_config_string(&line->chan_list, str, size, error_out);
 605         spin_unlock(&line->lock);
 606
 607         return n;
 608 }
 609
 610 int line_id(char **str, int *start_out, int *end_out)
 611 {
 612         char *end;
 613         int n;
 614
 615         n = simple_strtoul(*str, &end, 0);
 616         if((*end != '\0') || (end == *str))
 617                 return -1;
 618
 619         *str = end;
 620         *start_out = n;
 621         *end_out = n;
 622         return n;
 623 }
 624
 625 int line_remove(struct line *lines, unsigned int num, int n)
 626 {
 627         char config[sizeof("conxxxx=none\0")];
 628
 629         sprintf(config, "%d=none", n);
 630         return !line_setup(lines, num, config);
 631 }
 632
 633 struct tty_driver *line_register_devfs(struct lines *set,
 634                          struct line_driver *line_driver,
 635                          struct tty_operations *ops, struct line *lines,
 636                          int nlines)
 637 {
 638         int i;
 639         struct tty_driver *driver = alloc_tty_driver(nlines);
 640
 641         if (!driver)
 642                 return NULL;
 643
 644         driver->driver_name = line_driver->name;
 645         driver->name = line_driver->device_name;
 646         driver->devfs_name = line_driver->devfs_name;
 647         driver->major = line_driver->major;
 648         driver->minor_start = line_driver->minor_start;
 649         driver->type = line_driver->type;
 650         driver->subtype = line_driver->subtype;
 651         driver->flags = TTY_DRIVER_REAL_RAW;
 652         driver->init_termios = tty_std_termios;
 653         tty_set_operations(driver, ops);
 654
 655         if (tty_register_driver(driver)) {
 656                 printk("%s: can't register %s driver\n",
 657                        __FUNCTION__,line_driver->name);
 658                 put_tty_driver(driver);
 659                 return NULL;
 660         }
 661
 662         for(i = 0; i < nlines; i++){
 663                 if(!lines[i].valid)
 664                         tty_unregister_device(driver, i);
 665         }
 666
 667         mconsole_register_dev(&line_driver->mc);
 668         return driver;
 669 }
 670
 671 static DEFINE_SPINLOCK(winch_handler_lock);
 672 static LIST_HEAD(winch_handlers);
 673
 674 void lines_init(struct line *lines, int nlines)
 675 {
 676         struct line *line;
 677         int i;
 678
 679         for(i = 0; i < nlines; i++){
 680                 line = &lines[i];
 681                 INIT_LIST_HEAD(&line->chan_list);
 682
 683                 if(line->init_str == NULL)
 684                         continue;
 685
 686                 line->init_str = kstrdup(line->init_str, GFP_KERNEL);
 687                 if(line->init_str == NULL)
 688                         printk("lines_init - kstrdup returned NULL\n");
 689         }
 690 }
 691
 692 struct winch {
 693         struct list_head list;
 694         int fd;
 695         int tty_fd;
 696         int pid;
 697         struct tty_struct *tty;
 698 };
 699
 700 irqreturn_t winch_interrupt(int irq, void *data, struct pt_regs *unused)
 701 {
 702         struct winch *winch = data;
 703         struct tty_struct *tty;
 704         struct line *line;
 705         int err;
 706         char c;
 707
 708         if(winch->fd != -1){
 709                 err = generic_read(winch->fd, &c, NULL);
 710                 if(err < 0){
 711                         if(err != -EAGAIN){
 712                                 printk("winch_interrupt : read failed, "
 713                                        "errno = %d\n", -err);
 714                                 printk("fd %d is losing SIGWINCH support\n",
 715                                        winch->tty_fd);
 716                                 return IRQ_HANDLED;
 717                         }
 718                         goto out;
 719                 }
 720         }
 721         tty  = winch->tty;
 722         if (tty != NULL) {
 723                 line = tty->driver_data;
 724                 chan_window_size(&line->chan_list, &tty->winsize.ws_row,
 725                                  &tty->winsize.ws_col);
 726                 kill_pg(tty->pgrp, SIGWINCH, 1);
 727         }
 728  out:
 729         if(winch->fd != -1)
 730                 reactivate_fd(winch->fd, WINCH_IRQ);
 731         return IRQ_HANDLED;
 732 }
 733
 734 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty)
 735 {
 736         struct winch *winch;
 737
 738         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
 739         if (winch == NULL) {
 740                 printk("register_winch_irq - kmalloc failed\n");
 741                 return;
 742         }
 743
 744         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
 745                                    .fd          = fd,
 746                                    .tty_fd      = tty_fd,
 747                                    .pid         = pid,
 748                                    .tty         = tty });
 749
 750         spin_lock(&winch_handler_lock);
 751         list_add(&winch->list, &winch_handlers);
 752         spin_unlock(&winch_handler_lock);
 753
 754         if(um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 755                           SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM,
 756                           "winch", winch) < 0)
 757                 printk("register_winch_irq - failed to register IRQ\n");
 758 }
 759
 760 static void unregister_winch(struct tty_struct *tty)
 761 {
 762         struct list_head *ele;
 763         struct winch *winch, *found = NULL;
 764
 765         spin_lock(&winch_handler_lock);
 766         list_for_each(ele, &winch_handlers){
 767                 winch = list_entry(ele, struct winch, list);
 768                 if(winch->tty == tty){
 769                         found = winch;
 770                         break;
 771                 }
 772         }
 773         if(found == NULL)
 774                 goto err;
 775
 776         list_del(&winch->list);
 777         spin_unlock(&winch_handler_lock);
 778
 779         if(winch->pid != -1)
 780                 os_kill_process(winch->pid, 1);
 781
 782         free_irq(WINCH_IRQ, winch);
 783         kfree(winch);
 784
 785         return;
 786 err:
 787         spin_unlock(&winch_handler_lock);
 788 }
 789
 790 /* XXX: No lock as it's an exitcall... is this valid? Depending on cleanup
 791  * order... are we sure that nothing else is done on the list? */
 792 static void winch_cleanup(void)
 793 {
 794         struct list_head *ele;
 795         struct winch *winch;
 796
 797         list_for_each(ele, &winch_handlers){
 798                 winch = list_entry(ele, struct winch, list);
 799                 if(winch->fd != -1){
 800                         /* Why is this different from the above free_irq(),
 801                          * which deactivates SIGIO? This searches the FD
 802                          * somewhere else and removes it from the list... */
 803                         deactivate_fd(winch->fd, WINCH_IRQ);
 804                         os_close_file(winch->fd);
 805                 }
 806                 if(winch->pid != -1)
 807                         os_kill_process(winch->pid, 1);
 808         }
 809 }
 810 __uml_exitcall(winch_cleanup);
 811
 812 char *add_xterm_umid(char *base)
 813 {
 814         char *umid, *title;
 815         int len;
 816
 817         umid = get_umid(1);
 818         if(umid == NULL)
 819                 return base;
 820
 821         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 822         title = kmalloc(len, GFP_KERNEL);
 823         if(title == NULL){
 824                 printk("Failed to allocate buffer for xterm title\n");
 825                 return base;
 826         }
 827
 828         snprintf(title, len, "%s (%s)", base, umid);
 829         return title;
 830 }