xref: /openbmc/linux/arch/um/drivers/line.c (revision b6dcefde)
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 "linux/sched.h"
9 #include "chan_kern.h"
10 #include "irq_kern.h"
11 #include "irq_user.h"
12 #include "kern_util.h"
13 #include "os.h"
14 
15 #define LINE_BUFSIZE 4096
16 
17 static irqreturn_t line_interrupt(int irq, void *data)
18 {
19 	struct chan *chan = data;
20 	struct line *line = chan->line;
21 	struct tty_struct *tty = line->tty;
22 
23 	if (line)
24 		chan_interrupt(&line->chan_list, &line->task, tty, irq);
25 	return IRQ_HANDLED;
26 }
27 
28 static void line_timer_cb(struct work_struct *work)
29 {
30 	struct line *line = container_of(work, struct line, task.work);
31 
32 	if (!line->throttled)
33 		chan_interrupt(&line->chan_list, &line->task, line->tty,
34 			       line->driver->read_irq);
35 }
36 
37 /*
38  * Returns the free space inside the ring buffer of this line.
39  *
40  * Should be called while holding line->lock (this does not modify data).
41  */
42 static int write_room(struct line *line)
43 {
44 	int n;
45 
46 	if (line->buffer == NULL)
47 		return LINE_BUFSIZE - 1;
48 
49 	/* This is for the case where the buffer is wrapped! */
50 	n = line->head - line->tail;
51 
52 	if (n <= 0)
53 		n += LINE_BUFSIZE; /* The other case */
54 	return n - 1;
55 }
56 
57 int line_write_room(struct tty_struct *tty)
58 {
59 	struct line *line = tty->driver_data;
60 	unsigned long flags;
61 	int room;
62 
63 	spin_lock_irqsave(&line->lock, flags);
64 	room = write_room(line);
65 	spin_unlock_irqrestore(&line->lock, flags);
66 
67 	return room;
68 }
69 
70 int line_chars_in_buffer(struct tty_struct *tty)
71 {
72 	struct line *line = tty->driver_data;
73 	unsigned long flags;
74 	int ret;
75 
76 	spin_lock_irqsave(&line->lock, flags);
77 	/* write_room subtracts 1 for the needed NULL, so we readd it.*/
78 	ret = LINE_BUFSIZE - (write_room(line) + 1);
79 	spin_unlock_irqrestore(&line->lock, flags);
80 
81 	return ret;
82 }
83 
84 /*
85  * This copies the content of buf into the circular buffer associated with
86  * this line.
87  * The return value is the number of characters actually copied, i.e. the ones
88  * for which there was space: this function is not supposed to ever flush out
89  * the circular buffer.
90  *
91  * Must be called while holding line->lock!
92  */
93 static int buffer_data(struct line *line, const char *buf, int len)
94 {
95 	int end, room;
96 
97 	if (line->buffer == NULL) {
98 		line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
99 		if (line->buffer == NULL) {
100 			printk(KERN_ERR "buffer_data - atomic allocation "
101 			       "failed\n");
102 			return 0;
103 		}
104 		line->head = line->buffer;
105 		line->tail = line->buffer;
106 	}
107 
108 	room = write_room(line);
109 	len = (len > room) ? room : len;
110 
111 	end = line->buffer + LINE_BUFSIZE - line->tail;
112 
113 	if (len < end) {
114 		memcpy(line->tail, buf, len);
115 		line->tail += len;
116 	}
117 	else {
118 		/* The circular buffer is wrapping */
119 		memcpy(line->tail, buf, end);
120 		buf += end;
121 		memcpy(line->buffer, buf, len - end);
122 		line->tail = line->buffer + len - end;
123 	}
124 
125 	return len;
126 }
127 
128 /*
129  * Flushes the ring buffer to the output channels. That is, write_chan is
130  * called, passing it line->head as buffer, and an appropriate count.
131  *
132  * On exit, returns 1 when the buffer is empty,
133  * 0 when the buffer is not empty on exit,
134  * and -errno when an error occurred.
135  *
136  * Must be called while holding line->lock!*/
137 static int flush_buffer(struct line *line)
138 {
139 	int n, count;
140 
141 	if ((line->buffer == NULL) || (line->head == line->tail))
142 		return 1;
143 
144 	if (line->tail < line->head) {
145 		/* line->buffer + LINE_BUFSIZE is the end of the buffer! */
146 		count = line->buffer + LINE_BUFSIZE - line->head;
147 
148 		n = write_chan(&line->chan_list, line->head, count,
149 			       line->driver->write_irq);
150 		if (n < 0)
151 			return n;
152 		if (n == count) {
153 			/*
154 			 * We have flushed from ->head to buffer end, now we
155 			 * must flush only from the beginning to ->tail.
156 			 */
157 			line->head = line->buffer;
158 		} else {
159 			line->head += n;
160 			return 0;
161 		}
162 	}
163 
164 	count = line->tail - line->head;
165 	n = write_chan(&line->chan_list, line->head, count,
166 		       line->driver->write_irq);
167 
168 	if (n < 0)
169 		return n;
170 
171 	line->head += n;
172 	return line->head == line->tail;
173 }
174 
175 void line_flush_buffer(struct tty_struct *tty)
176 {
177 	struct line *line = tty->driver_data;
178 	unsigned long flags;
179 	int err;
180 
181 	spin_lock_irqsave(&line->lock, flags);
182 	err = flush_buffer(line);
183 	spin_unlock_irqrestore(&line->lock, flags);
184 }
185 
186 /*
187  * We map both ->flush_chars and ->put_char (which go in pair) onto
188  * ->flush_buffer and ->write. Hope it's not that bad.
189  */
190 void line_flush_chars(struct tty_struct *tty)
191 {
192 	line_flush_buffer(tty);
193 }
194 
195 int line_put_char(struct tty_struct *tty, unsigned char ch)
196 {
197 	return line_write(tty, &ch, sizeof(ch));
198 }
199 
200 int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
201 {
202 	struct line *line = tty->driver_data;
203 	unsigned long flags;
204 	int n, ret = 0;
205 
206 	spin_lock_irqsave(&line->lock, flags);
207 	if (line->head != line->tail)
208 		ret = buffer_data(line, buf, len);
209 	else {
210 		n = write_chan(&line->chan_list, buf, len,
211 			       line->driver->write_irq);
212 		if (n < 0) {
213 			ret = n;
214 			goto out_up;
215 		}
216 
217 		len -= n;
218 		ret += n;
219 		if (len > 0)
220 			ret += buffer_data(line, buf + n, len);
221 	}
222 out_up:
223 	spin_unlock_irqrestore(&line->lock, flags);
224 	return ret;
225 }
226 
227 void line_set_termios(struct tty_struct *tty, struct ktermios * old)
228 {
229 	/* nothing */
230 }
231 
232 static const struct {
233 	int  cmd;
234 	char *level;
235 	char *name;
236 } tty_ioctls[] = {
237 	/* don't print these, they flood the log ... */
238 	{ TCGETS,      NULL,       "TCGETS"      },
239 	{ TCSETS,      NULL,       "TCSETS"      },
240 	{ TCSETSW,     NULL,       "TCSETSW"     },
241 	{ TCFLSH,      NULL,       "TCFLSH"      },
242 	{ TCSBRK,      NULL,       "TCSBRK"      },
243 
244 	/* general tty stuff */
245 	{ TCSETSF,     KERN_DEBUG, "TCSETSF"     },
246 	{ TCGETA,      KERN_DEBUG, "TCGETA"      },
247 	{ TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
248 	{ TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
249 	{ TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },
250 
251 	/* linux-specific ones */
252 	{ TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
253 	{ KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
254 	{ KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
255 	{ KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
256 };
257 
258 int line_ioctl(struct tty_struct *tty, struct file * file,
259 	       unsigned int cmd, unsigned long arg)
260 {
261 	int ret;
262 	int i;
263 
264 	ret = 0;
265 	switch(cmd) {
266 #ifdef TIOCGETP
267 	case TIOCGETP:
268 	case TIOCSETP:
269 	case TIOCSETN:
270 #endif
271 #ifdef TIOCGETC
272 	case TIOCGETC:
273 	case TIOCSETC:
274 #endif
275 #ifdef TIOCGLTC
276 	case TIOCGLTC:
277 	case TIOCSLTC:
278 #endif
279 	/* Note: these are out of date as we now have TCGETS2 etc but this
280 	   whole lot should probably go away */
281 	case TCGETS:
282 	case TCSETSF:
283 	case TCSETSW:
284 	case TCSETS:
285 	case TCGETA:
286 	case TCSETAF:
287 	case TCSETAW:
288 	case TCSETA:
289 	case TCXONC:
290 	case TCFLSH:
291 	case TIOCOUTQ:
292 	case TIOCINQ:
293 	case TIOCGLCKTRMIOS:
294 	case TIOCSLCKTRMIOS:
295 	case TIOCPKT:
296 	case TIOCGSOFTCAR:
297 	case TIOCSSOFTCAR:
298 		return -ENOIOCTLCMD;
299 #if 0
300 	case TCwhatever:
301 		/* do something */
302 		break;
303 #endif
304 	default:
305 		for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
306 			if (cmd == tty_ioctls[i].cmd)
307 				break;
308 		if (i == ARRAY_SIZE(tty_ioctls)) {
309 			printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
310 			       __func__, tty->name, cmd);
311 		}
312 		ret = -ENOIOCTLCMD;
313 		break;
314 	}
315 	return ret;
316 }
317 
318 void line_throttle(struct tty_struct *tty)
319 {
320 	struct line *line = tty->driver_data;
321 
322 	deactivate_chan(&line->chan_list, line->driver->read_irq);
323 	line->throttled = 1;
324 }
325 
326 void line_unthrottle(struct tty_struct *tty)
327 {
328 	struct line *line = tty->driver_data;
329 
330 	line->throttled = 0;
331 	chan_interrupt(&line->chan_list, &line->task, tty,
332 		       line->driver->read_irq);
333 
334 	/*
335 	 * Maybe there is enough stuff pending that calling the interrupt
336 	 * throttles us again.  In this case, line->throttled will be 1
337 	 * again and we shouldn't turn the interrupt back on.
338 	 */
339 	if (!line->throttled)
340 		reactivate_chan(&line->chan_list, line->driver->read_irq);
341 }
342 
343 static irqreturn_t line_write_interrupt(int irq, void *data)
344 {
345 	struct chan *chan = data;
346 	struct line *line = chan->line;
347 	struct tty_struct *tty = line->tty;
348 	int err;
349 
350 	/*
351 	 * Interrupts are disabled here because we registered the interrupt with
352 	 * IRQF_DISABLED (see line_setup_irq).
353 	 */
354 
355 	spin_lock(&line->lock);
356 	err = flush_buffer(line);
357 	if (err == 0) {
358 		return IRQ_NONE;
359 	} else if (err < 0) {
360 		line->head = line->buffer;
361 		line->tail = line->buffer;
362 	}
363 	spin_unlock(&line->lock);
364 
365 	if (tty == NULL)
366 		return IRQ_NONE;
367 
368 	tty_wakeup(tty);
369 	return IRQ_HANDLED;
370 }
371 
372 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
373 {
374 	const struct line_driver *driver = line->driver;
375 	int err = 0, flags = IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM;
376 
377 	if (input)
378 		err = um_request_irq(driver->read_irq, fd, IRQ_READ,
379 				       line_interrupt, flags,
380 				       driver->read_irq_name, data);
381 	if (err)
382 		return err;
383 	if (output)
384 		err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
385 					line_write_interrupt, flags,
386 					driver->write_irq_name, data);
387 	line->have_irq = 1;
388 	return err;
389 }
390 
391 /*
392  * Normally, a driver like this can rely mostly on the tty layer
393  * locking, particularly when it comes to the driver structure.
394  * However, in this case, mconsole requests can come in "from the
395  * side", and race with opens and closes.
396  *
397  * mconsole config requests will want to be sure the device isn't in
398  * use, and get_config, open, and close will want a stable
399  * configuration.  The checking and modification of the configuration
400  * is done under a spinlock.  Checking whether the device is in use is
401  * line->tty->count > 1, also under the spinlock.
402  *
403  * tty->count serves to decide whether the device should be enabled or
404  * disabled on the host.  If it's equal to 1, then we are doing the
405  * first open or last close.  Otherwise, open and close just return.
406  */
407 
408 int line_open(struct line *lines, struct tty_struct *tty)
409 {
410 	struct line *line = &lines[tty->index];
411 	int err = -ENODEV;
412 
413 	spin_lock(&line->count_lock);
414 	if (!line->valid)
415 		goto out_unlock;
416 
417 	err = 0;
418 	if (tty->count > 1)
419 		goto out_unlock;
420 
421 	spin_unlock(&line->count_lock);
422 
423 	tty->driver_data = line;
424 	line->tty = tty;
425 
426 	err = enable_chan(line);
427 	if (err)
428 		return err;
429 
430 	INIT_DELAYED_WORK(&line->task, line_timer_cb);
431 
432 	if (!line->sigio) {
433 		chan_enable_winch(&line->chan_list, tty);
434 		line->sigio = 1;
435 	}
436 
437 	chan_window_size(&line->chan_list, &tty->winsize.ws_row,
438 			 &tty->winsize.ws_col);
439 
440 	return err;
441 
442 out_unlock:
443 	spin_unlock(&line->count_lock);
444 	return err;
445 }
446 
447 static void unregister_winch(struct tty_struct *tty);
448 
449 void line_close(struct tty_struct *tty, struct file * filp)
450 {
451 	struct line *line = tty->driver_data;
452 
453 	/*
454 	 * If line_open fails (and tty->driver_data is never set),
455 	 * tty_open will call line_close.  So just return in this case.
456 	 */
457 	if (line == NULL)
458 		return;
459 
460 	/* We ignore the error anyway! */
461 	flush_buffer(line);
462 
463 	spin_lock(&line->count_lock);
464 	if (!line->valid)
465 		goto out_unlock;
466 
467 	if (tty->count > 1)
468 		goto out_unlock;
469 
470 	spin_unlock(&line->count_lock);
471 
472 	line->tty = NULL;
473 	tty->driver_data = NULL;
474 
475 	if (line->sigio) {
476 		unregister_winch(tty);
477 		line->sigio = 0;
478 	}
479 
480 	return;
481 
482 out_unlock:
483 	spin_unlock(&line->count_lock);
484 }
485 
486 void close_lines(struct line *lines, int nlines)
487 {
488 	int i;
489 
490 	for(i = 0; i < nlines; i++)
491 		close_chan(&lines[i].chan_list, 0);
492 }
493 
494 static int setup_one_line(struct line *lines, int n, char *init, int init_prio,
495 			  char **error_out)
496 {
497 	struct line *line = &lines[n];
498 	int err = -EINVAL;
499 
500 	spin_lock(&line->count_lock);
501 
502 	if (line->tty != NULL) {
503 		*error_out = "Device is already open";
504 		goto out;
505 	}
506 
507 	if (line->init_pri <= init_prio) {
508 		line->init_pri = init_prio;
509 		if (!strcmp(init, "none"))
510 			line->valid = 0;
511 		else {
512 			line->init_str = init;
513 			line->valid = 1;
514 		}
515 	}
516 	err = 0;
517 out:
518 	spin_unlock(&line->count_lock);
519 	return err;
520 }
521 
522 /*
523  * Common setup code for both startup command line and mconsole initialization.
524  * @lines contains the array (of size @num) to modify;
525  * @init is the setup string;
526  * @error_out is an error string in the case of failure;
527  */
528 
529 int line_setup(struct line *lines, unsigned int num, char *init,
530 	       char **error_out)
531 {
532 	int i, n, err;
533 	char *end;
534 
535 	if (*init == '=') {
536 		/*
537 		 * We said con=/ssl= instead of con#=, so we are configuring all
538 		 * consoles at once.
539 		 */
540 		n = -1;
541 	}
542 	else {
543 		n = simple_strtoul(init, &end, 0);
544 		if (*end != '=') {
545 			*error_out = "Couldn't parse device number";
546 			return -EINVAL;
547 		}
548 		init = end;
549 	}
550 	init++;
551 
552 	if (n >= (signed int) num) {
553 		*error_out = "Device number out of range";
554 		return -EINVAL;
555 	}
556 	else if (n >= 0) {
557 		err = setup_one_line(lines, n, init, INIT_ONE, error_out);
558 		if (err)
559 			return err;
560 	}
561 	else {
562 		for(i = 0; i < num; i++) {
563 			err = setup_one_line(lines, i, init, INIT_ALL,
564 					     error_out);
565 			if (err)
566 				return err;
567 		}
568 	}
569 	return n == -1 ? num : n;
570 }
571 
572 int line_config(struct line *lines, unsigned int num, char *str,
573 		const struct chan_opts *opts, char **error_out)
574 {
575 	struct line *line;
576 	char *new;
577 	int n;
578 
579 	if (*str == '=') {
580 		*error_out = "Can't configure all devices from mconsole";
581 		return -EINVAL;
582 	}
583 
584 	new = kstrdup(str, GFP_KERNEL);
585 	if (new == NULL) {
586 		*error_out = "Failed to allocate memory";
587 		return -ENOMEM;
588 	}
589 	n = line_setup(lines, num, new, error_out);
590 	if (n < 0)
591 		return n;
592 
593 	line = &lines[n];
594 	return parse_chan_pair(line->init_str, line, n, opts, error_out);
595 }
596 
597 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
598 		    int size, char **error_out)
599 {
600 	struct line *line;
601 	char *end;
602 	int dev, n = 0;
603 
604 	dev = simple_strtoul(name, &end, 0);
605 	if ((*end != '\0') || (end == name)) {
606 		*error_out = "line_get_config failed to parse device number";
607 		return 0;
608 	}
609 
610 	if ((dev < 0) || (dev >= num)) {
611 		*error_out = "device number out of range";
612 		return 0;
613 	}
614 
615 	line = &lines[dev];
616 
617 	spin_lock(&line->count_lock);
618 	if (!line->valid)
619 		CONFIG_CHUNK(str, size, n, "none", 1);
620 	else if (line->tty == NULL)
621 		CONFIG_CHUNK(str, size, n, line->init_str, 1);
622 	else n = chan_config_string(&line->chan_list, str, size, error_out);
623 	spin_unlock(&line->count_lock);
624 
625 	return n;
626 }
627 
628 int line_id(char **str, int *start_out, int *end_out)
629 {
630 	char *end;
631 	int n;
632 
633 	n = simple_strtoul(*str, &end, 0);
634 	if ((*end != '\0') || (end == *str))
635 		return -1;
636 
637 	*str = end;
638 	*start_out = n;
639 	*end_out = n;
640 	return n;
641 }
642 
643 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
644 {
645 	int err;
646 	char config[sizeof("conxxxx=none\0")];
647 
648 	sprintf(config, "%d=none", n);
649 	err = line_setup(lines, num, config, error_out);
650 	if (err >= 0)
651 		err = 0;
652 	return err;
653 }
654 
655 struct tty_driver *register_lines(struct line_driver *line_driver,
656 				  const struct tty_operations *ops,
657 				  struct line *lines, int nlines)
658 {
659 	int i;
660 	struct tty_driver *driver = alloc_tty_driver(nlines);
661 
662 	if (!driver)
663 		return NULL;
664 
665 	driver->driver_name = line_driver->name;
666 	driver->name = line_driver->device_name;
667 	driver->major = line_driver->major;
668 	driver->minor_start = line_driver->minor_start;
669 	driver->type = line_driver->type;
670 	driver->subtype = line_driver->subtype;
671 	driver->flags = TTY_DRIVER_REAL_RAW;
672 	driver->init_termios = tty_std_termios;
673 	tty_set_operations(driver, ops);
674 
675 	if (tty_register_driver(driver)) {
676 		printk(KERN_ERR "register_lines : can't register %s driver\n",
677 		       line_driver->name);
678 		put_tty_driver(driver);
679 		return NULL;
680 	}
681 
682 	for(i = 0; i < nlines; i++) {
683 		if (!lines[i].valid)
684 			tty_unregister_device(driver, i);
685 	}
686 
687 	mconsole_register_dev(&line_driver->mc);
688 	return driver;
689 }
690 
691 static DEFINE_SPINLOCK(winch_handler_lock);
692 static LIST_HEAD(winch_handlers);
693 
694 void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
695 {
696 	struct line *line;
697 	char *error;
698 	int i;
699 
700 	for(i = 0; i < nlines; i++) {
701 		line = &lines[i];
702 		INIT_LIST_HEAD(&line->chan_list);
703 
704 		if (line->init_str == NULL)
705 			continue;
706 
707 		line->init_str = kstrdup(line->init_str, GFP_KERNEL);
708 		if (line->init_str == NULL)
709 			printk(KERN_ERR "lines_init - kstrdup returned NULL\n");
710 
711 		if (parse_chan_pair(line->init_str, line, i, opts, &error)) {
712 			printk(KERN_ERR "parse_chan_pair failed for "
713 			       "device %d : %s\n", i, error);
714 			line->valid = 0;
715 		}
716 	}
717 }
718 
719 struct winch {
720 	struct list_head list;
721 	int fd;
722 	int tty_fd;
723 	int pid;
724 	struct tty_struct *tty;
725 	unsigned long stack;
726 };
727 
728 static void free_winch(struct winch *winch, int free_irq_ok)
729 {
730 	list_del(&winch->list);
731 
732 	if (winch->pid != -1)
733 		os_kill_process(winch->pid, 1);
734 	if (winch->fd != -1)
735 		os_close_file(winch->fd);
736 	if (winch->stack != 0)
737 		free_stack(winch->stack, 0);
738 	if (free_irq_ok)
739 		free_irq(WINCH_IRQ, winch);
740 	kfree(winch);
741 }
742 
743 static irqreturn_t winch_interrupt(int irq, void *data)
744 {
745 	struct winch *winch = data;
746 	struct tty_struct *tty;
747 	struct line *line;
748 	int err;
749 	char c;
750 
751 	if (winch->fd != -1) {
752 		err = generic_read(winch->fd, &c, NULL);
753 		if (err < 0) {
754 			if (err != -EAGAIN) {
755 				printk(KERN_ERR "winch_interrupt : "
756 				       "read failed, errno = %d\n", -err);
757 				printk(KERN_ERR "fd %d is losing SIGWINCH "
758 				       "support\n", winch->tty_fd);
759 				free_winch(winch, 0);
760 				return IRQ_HANDLED;
761 			}
762 			goto out;
763 		}
764 	}
765 	tty = winch->tty;
766 	if (tty != NULL) {
767 		line = tty->driver_data;
768 		if (line != NULL) {
769 			chan_window_size(&line->chan_list, &tty->winsize.ws_row,
770 					 &tty->winsize.ws_col);
771 			kill_pgrp(tty->pgrp, SIGWINCH, 1);
772 		}
773 	}
774  out:
775 	if (winch->fd != -1)
776 		reactivate_fd(winch->fd, WINCH_IRQ);
777 	return IRQ_HANDLED;
778 }
779 
780 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
781 			unsigned long stack)
782 {
783 	struct winch *winch;
784 
785 	winch = kmalloc(sizeof(*winch), GFP_KERNEL);
786 	if (winch == NULL) {
787 		printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
788 		goto cleanup;
789 	}
790 
791 	*winch = ((struct winch) { .list  	= LIST_HEAD_INIT(winch->list),
792 				   .fd  	= fd,
793 				   .tty_fd 	= tty_fd,
794 				   .pid  	= pid,
795 				   .tty 	= tty,
796 				   .stack	= stack });
797 
798 	if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
799 			   IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
800 			   "winch", winch) < 0) {
801 		printk(KERN_ERR "register_winch_irq - failed to register "
802 		       "IRQ\n");
803 		goto out_free;
804 	}
805 
806 	spin_lock(&winch_handler_lock);
807 	list_add(&winch->list, &winch_handlers);
808 	spin_unlock(&winch_handler_lock);
809 
810 	return;
811 
812  out_free:
813 	kfree(winch);
814  cleanup:
815 	os_kill_process(pid, 1);
816 	os_close_file(fd);
817 	if (stack != 0)
818 		free_stack(stack, 0);
819 }
820 
821 static void unregister_winch(struct tty_struct *tty)
822 {
823 	struct list_head *ele;
824 	struct winch *winch;
825 
826 	spin_lock(&winch_handler_lock);
827 
828 	list_for_each(ele, &winch_handlers) {
829 		winch = list_entry(ele, struct winch, list);
830 		if (winch->tty == tty) {
831 			free_winch(winch, 1);
832 			break;
833 		}
834 	}
835 	spin_unlock(&winch_handler_lock);
836 }
837 
838 static void winch_cleanup(void)
839 {
840 	struct list_head *ele, *next;
841 	struct winch *winch;
842 
843 	spin_lock(&winch_handler_lock);
844 
845 	list_for_each_safe(ele, next, &winch_handlers) {
846 		winch = list_entry(ele, struct winch, list);
847 		free_winch(winch, 1);
848 	}
849 
850 	spin_unlock(&winch_handler_lock);
851 }
852 __uml_exitcall(winch_cleanup);
853 
854 char *add_xterm_umid(char *base)
855 {
856 	char *umid, *title;
857 	int len;
858 
859 	umid = get_umid();
860 	if (*umid == '\0')
861 		return base;
862 
863 	len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
864 	title = kmalloc(len, GFP_KERNEL);
865 	if (title == NULL) {
866 		printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
867 		return base;
868 	}
869 
870 	snprintf(title, len, "%s (%s)", base, umid);
871 	return title;
872 }
873