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