Merge master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6
[linux-2.6] / 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)
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 {
369         struct chan *chan = data;
370         struct line *line = chan->line;
371         struct tty_struct *tty = line->tty;
372         int err;
373
374         /* Interrupts are enabled here because we registered the interrupt with
375          * IRQF_DISABLED (see line_setup_irq).*/
376
377         spin_lock_irq(&line->lock);
378         err = flush_buffer(line);
379         if (err == 0) {
380                 return IRQ_NONE;
381         } else if(err < 0) {
382                 line->head = line->buffer;
383                 line->tail = line->buffer;
384         }
385         spin_unlock_irq(&line->lock);
386
387         if(tty == NULL)
388                 return IRQ_NONE;
389
390         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
391            (tty->ldisc.write_wakeup != NULL))
392                 (tty->ldisc.write_wakeup)(tty);
393
394         /* BLOCKING mode
395          * In blocking mode, everything sleeps on tty->write_wait.
396          * Sleeping in the console driver would break non-blocking
397          * writes.
398          */
399
400         if (waitqueue_active(&tty->write_wait))
401                 wake_up_interruptible(&tty->write_wait);
402         return IRQ_HANDLED;
403 }
404
405 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
406 {
407         const struct line_driver *driver = line->driver;
408         int err = 0, flags = IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM;
409
410         if (input)
411                 err = um_request_irq(driver->read_irq, fd, IRQ_READ,
412                                        line_interrupt, flags,
413                                        driver->read_irq_name, data);
414         if (err)
415                 return err;
416         if (output)
417                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
418                                         line_write_interrupt, flags,
419                                         driver->write_irq_name, data);
420         line->have_irq = 1;
421         return err;
422 }
423
424 int line_open(struct line *lines, struct tty_struct *tty)
425 {
426         struct line *line;
427         int err = -ENODEV;
428
429         line = &lines[tty->index];
430         tty->driver_data = line;
431
432         /* The IRQ which takes this lock is not yet enabled and won't be run
433          * before the end, so we don't need to use spin_lock_irq.*/
434         spin_lock(&line->lock);
435
436         tty->driver_data = line;
437         line->tty = tty;
438         if(!line->valid)
439                 goto out;
440
441         if(tty->count == 1){
442                 /* Here the device is opened, if necessary, and interrupt
443                  * is registered.
444                  */
445                 enable_chan(line);
446                 INIT_WORK(&line->task, line_timer_cb, line);
447
448                 if(!line->sigio){
449                         chan_enable_winch(&line->chan_list, tty);
450                         line->sigio = 1;
451                 }
452
453                 chan_window_size(&line->chan_list, &tty->winsize.ws_row,
454                                  &tty->winsize.ws_col);
455         }
456
457         err = 0;
458 out:
459         spin_unlock(&line->lock);
460         return err;
461 }
462
463 static void unregister_winch(struct tty_struct *tty);
464
465 void line_close(struct tty_struct *tty, struct file * filp)
466 {
467         struct line *line = tty->driver_data;
468
469         /* XXX: I assume this should be called in process context, not with
470          *  interrupts disabled!
471          */
472         spin_lock_irq(&line->lock);
473
474         /* We ignore the error anyway! */
475         flush_buffer(line);
476
477         if(tty->count == 1){
478                 line->tty = NULL;
479                 tty->driver_data = NULL;
480
481                 if(line->sigio){
482                         unregister_winch(tty);
483                         line->sigio = 0;
484                 }
485         }
486
487         spin_unlock_irq(&line->lock);
488 }
489
490 void close_lines(struct line *lines, int nlines)
491 {
492         int i;
493
494         for(i = 0; i < nlines; i++)
495                 close_chan(&lines[i].chan_list, 0);
496 }
497
498 /* Common setup code for both startup command line and mconsole initialization.
499  * @lines contains the array (of size @num) to modify;
500  * @init is the setup string;
501  */
502
503 int line_setup(struct line *lines, unsigned int num, char *init)
504 {
505         int i, n;
506         char *end;
507
508         if(*init == '=') {
509                 /* We said con=/ssl= instead of con#=, so we are configuring all
510                  * consoles at once.*/
511                 n = -1;
512         }
513         else {
514                 n = simple_strtoul(init, &end, 0);
515                 if(*end != '='){
516                         printk(KERN_ERR "line_setup failed to parse \"%s\"\n",
517                                init);
518                         return 0;
519                 }
520                 init = end;
521         }
522         init++;
523
524         if (n >= (signed int) num) {
525                 printk("line_setup - %d out of range ((0 ... %d) allowed)\n",
526                        n, num - 1);
527                 return 0;
528         }
529         else if (n >= 0){
530                 if (lines[n].tty != NULL) {
531                         printk("line_setup - device %d is open\n", n);
532                         return 0;
533                 }
534                 if (lines[n].init_pri <= INIT_ONE){
535                         lines[n].init_pri = INIT_ONE;
536                         if (!strcmp(init, "none"))
537                                 lines[n].valid = 0;
538                         else {
539                                 lines[n].init_str = init;
540                                 lines[n].valid = 1;
541                         }
542                 }
543         }
544         else {
545                 for(i = 0; i < num; i++){
546                         if(lines[i].init_pri <= INIT_ALL){
547                                 lines[i].init_pri = INIT_ALL;
548                                 if(!strcmp(init, "none")) lines[i].valid = 0;
549                                 else {
550                                         lines[i].init_str = init;
551                                         lines[i].valid = 1;
552                                 }
553                         }
554                 }
555         }
556         return n == -1 ? num : n;
557 }
558
559 int line_config(struct line *lines, unsigned int num, char *str,
560                 const struct chan_opts *opts)
561 {
562         struct line *line;
563         char *new;
564         int n;
565
566         if(*str == '='){
567                 printk("line_config - can't configure all devices from "
568                        "mconsole\n");
569                 return 1;
570         }
571
572         new = kstrdup(str, GFP_KERNEL);
573         if(new == NULL){
574                 printk("line_config - kstrdup failed\n");
575                 return 1;
576         }
577         n = line_setup(lines, num, new);
578         if(n < 0)
579                 return 1;
580
581         line = &lines[n];
582         return parse_chan_pair(line->init_str, line, n, opts);
583 }
584
585 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
586                     int size, char **error_out)
587 {
588         struct line *line;
589         char *end;
590         int dev, n = 0;
591
592         dev = simple_strtoul(name, &end, 0);
593         if((*end != '\0') || (end == name)){
594                 *error_out = "line_get_config failed to parse device number";
595                 return 0;
596         }
597
598         if((dev < 0) || (dev >= num)){
599                 *error_out = "device number out of range";
600                 return 0;
601         }
602
603         line = &lines[dev];
604
605         spin_lock(&line->lock);
606         if(!line->valid)
607                 CONFIG_CHUNK(str, size, n, "none", 1);
608         else if(line->tty == NULL)
609                 CONFIG_CHUNK(str, size, n, line->init_str, 1);
610         else n = chan_config_string(&line->chan_list, str, size, error_out);
611         spin_unlock(&line->lock);
612
613         return n;
614 }
615
616 int line_id(char **str, int *start_out, int *end_out)
617 {
618         char *end;
619         int n;
620
621         n = simple_strtoul(*str, &end, 0);
622         if((*end != '\0') || (end == *str))
623                 return -1;
624
625         *str = end;
626         *start_out = n;
627         *end_out = n;
628         return n;
629 }
630
631 int line_remove(struct line *lines, unsigned int num, int n)
632 {
633         int err;
634         char config[sizeof("conxxxx=none\0")];
635
636         sprintf(config, "%d=none", n);
637         err = line_setup(lines, num, config);
638         if(err >= 0)
639                 err = 0;
640         return err;
641 }
642
643 struct tty_driver *line_register_devfs(struct lines *set,
644                                        struct line_driver *line_driver,
645                                        const struct tty_operations *ops,
646                                        struct line *lines, int nlines)
647 {
648         int i;
649         struct tty_driver *driver = alloc_tty_driver(nlines);
650
651         if (!driver)
652                 return NULL;
653
654         driver->driver_name = line_driver->name;
655         driver->name = line_driver->device_name;
656         driver->major = line_driver->major;
657         driver->minor_start = line_driver->minor_start;
658         driver->type = line_driver->type;
659         driver->subtype = line_driver->subtype;
660         driver->flags = TTY_DRIVER_REAL_RAW;
661         driver->init_termios = tty_std_termios;
662         tty_set_operations(driver, ops);
663
664         if (tty_register_driver(driver)) {
665                 printk("%s: can't register %s driver\n",
666                        __FUNCTION__,line_driver->name);
667                 put_tty_driver(driver);
668                 return NULL;
669         }
670
671         for(i = 0; i < nlines; i++){
672                 if(!lines[i].valid)
673                         tty_unregister_device(driver, i);
674         }
675
676         mconsole_register_dev(&line_driver->mc);
677         return driver;
678 }
679
680 static DEFINE_SPINLOCK(winch_handler_lock);
681 static LIST_HEAD(winch_handlers);
682
683 void lines_init(struct line *lines, int nlines, struct chan_opts *opts)
684 {
685         struct line *line;
686         int i;
687
688         for(i = 0; i < nlines; i++){
689                 line = &lines[i];
690                 INIT_LIST_HEAD(&line->chan_list);
691
692                 if(line->init_str == NULL)
693                         continue;
694
695                 line->init_str = kstrdup(line->init_str, GFP_KERNEL);
696                 if(line->init_str == NULL)
697                         printk("lines_init - kstrdup returned NULL\n");
698
699                 if(parse_chan_pair(line->init_str, line, i, opts)){
700                         printk("parse_chan_pair failed for device %d\n", i);
701                         line->valid = 0;
702                 }
703         }
704 }
705
706 struct winch {
707         struct list_head list;
708         int fd;
709         int tty_fd;
710         int pid;
711         struct tty_struct *tty;
712 };
713
714 static irqreturn_t winch_interrupt(int irq, void *data)
715 {
716         struct winch *winch = data;
717         struct tty_struct *tty;
718         struct line *line;
719         int err;
720         char c;
721
722         if(winch->fd != -1){
723                 err = generic_read(winch->fd, &c, NULL);
724                 if(err < 0){
725                         if(err != -EAGAIN){
726                                 printk("winch_interrupt : read failed, "
727                                        "errno = %d\n", -err);
728                                 printk("fd %d is losing SIGWINCH support\n",
729                                        winch->tty_fd);
730                                 return IRQ_HANDLED;
731                         }
732                         goto out;
733                 }
734         }
735         tty  = winch->tty;
736         if (tty != NULL) {
737                 line = tty->driver_data;
738                 chan_window_size(&line->chan_list, &tty->winsize.ws_row,
739                                  &tty->winsize.ws_col);
740                 kill_pg(tty->pgrp, SIGWINCH, 1);
741         }
742  out:
743         if(winch->fd != -1)
744                 reactivate_fd(winch->fd, WINCH_IRQ);
745         return IRQ_HANDLED;
746 }
747
748 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty)
749 {
750         struct winch *winch;
751
752         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
753         if (winch == NULL) {
754                 printk("register_winch_irq - kmalloc failed\n");
755                 return;
756         }
757
758         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
759                                    .fd          = fd,
760                                    .tty_fd      = tty_fd,
761                                    .pid         = pid,
762                                    .tty         = tty });
763
764         spin_lock(&winch_handler_lock);
765         list_add(&winch->list, &winch_handlers);
766         spin_unlock(&winch_handler_lock);
767
768         if(um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
769                           IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
770                           "winch", winch) < 0)
771                 printk("register_winch_irq - failed to register IRQ\n");
772 }
773
774 static void free_winch(struct winch *winch)
775 {
776         list_del(&winch->list);
777
778         if(winch->pid != -1)
779                 os_kill_process(winch->pid, 1);
780         if(winch->fd != -1)
781                 os_close_file(winch->fd);
782
783         free_irq(WINCH_IRQ, winch);
784         kfree(winch);
785 }
786
787 static void unregister_winch(struct tty_struct *tty)
788 {
789         struct list_head *ele;
790         struct winch *winch;
791
792         spin_lock(&winch_handler_lock);
793
794         list_for_each(ele, &winch_handlers){
795                 winch = list_entry(ele, struct winch, list);
796                 if(winch->tty == tty){
797                         free_winch(winch);
798                         break;
799                 }
800         }
801         spin_unlock(&winch_handler_lock);
802 }
803
804 static void winch_cleanup(void)
805 {
806         struct list_head *ele, *next;
807         struct winch *winch;
808
809         spin_lock(&winch_handler_lock);
810
811         list_for_each_safe(ele, next, &winch_handlers){
812                 winch = list_entry(ele, struct winch, list);
813                 free_winch(winch);
814         }
815
816         spin_unlock(&winch_handler_lock);
817 }
818 __uml_exitcall(winch_cleanup);
819
820 char *add_xterm_umid(char *base)
821 {
822         char *umid, *title;
823         int len;
824
825         umid = get_umid();
826         if(*umid == '\0')
827                 return base;
828
829         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
830         title = kmalloc(len, GFP_KERNEL);
831         if(title == NULL){
832                 printk("Failed to allocate buffer for xterm title\n");
833                 return base;
834         }
835
836         snprintf(title, len, "%s (%s)", base, umid);
837         return title;
838 }