Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 : */
5 :
6 : #include <linux/irqreturn.h>
7 : #include <linux/kd.h>
8 : #include <linux/sched/signal.h>
9 : #include <linux/slab.h>
10 :
11 : #include "chan.h"
12 : #include <irq_kern.h>
13 : #include <irq_user.h>
14 : #include <kern_util.h>
15 : #include <os.h>
16 :
17 : #define LINE_BUFSIZE 4096
18 :
19 0 : static irqreturn_t line_interrupt(int irq, void *data)
20 : {
21 0 : struct chan *chan = data;
22 0 : struct line *line = chan->line;
23 :
24 0 : if (line)
25 0 : chan_interrupt(line, irq);
26 :
27 0 : return IRQ_HANDLED;
28 : }
29 :
30 : /*
31 : * Returns the free space inside the ring buffer of this line.
32 : *
33 : * Should be called while holding line->lock (this does not modify data).
34 : */
35 : static unsigned int write_room(struct line *line)
36 : {
37 : int n;
38 :
39 0 : if (line->buffer == NULL)
40 : return LINE_BUFSIZE - 1;
41 :
42 : /* This is for the case where the buffer is wrapped! */
43 0 : n = line->head - line->tail;
44 :
45 0 : if (n <= 0)
46 0 : n += LINE_BUFSIZE; /* The other case */
47 0 : return n - 1;
48 : }
49 :
50 0 : unsigned int line_write_room(struct tty_struct *tty)
51 : {
52 0 : struct line *line = tty->driver_data;
53 : unsigned long flags;
54 : unsigned int room;
55 :
56 0 : spin_lock_irqsave(&line->lock, flags);
57 0 : room = write_room(line);
58 0 : spin_unlock_irqrestore(&line->lock, flags);
59 :
60 0 : return room;
61 : }
62 :
63 0 : unsigned int line_chars_in_buffer(struct tty_struct *tty)
64 : {
65 0 : struct line *line = tty->driver_data;
66 : unsigned long flags;
67 : unsigned int ret;
68 :
69 0 : spin_lock_irqsave(&line->lock, flags);
70 : /* write_room subtracts 1 for the needed NULL, so we readd it.*/
71 0 : ret = LINE_BUFSIZE - (write_room(line) + 1);
72 0 : spin_unlock_irqrestore(&line->lock, flags);
73 :
74 0 : return ret;
75 : }
76 :
77 : /*
78 : * This copies the content of buf into the circular buffer associated with
79 : * this line.
80 : * The return value is the number of characters actually copied, i.e. the ones
81 : * for which there was space: this function is not supposed to ever flush out
82 : * the circular buffer.
83 : *
84 : * Must be called while holding line->lock!
85 : */
86 0 : static int buffer_data(struct line *line, const char *buf, int len)
87 : {
88 : int end, room;
89 :
90 0 : if (line->buffer == NULL) {
91 0 : line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
92 0 : if (line->buffer == NULL) {
93 0 : printk(KERN_ERR "buffer_data - atomic allocation "
94 : "failed\n");
95 0 : return 0;
96 : }
97 0 : line->head = line->buffer;
98 0 : line->tail = line->buffer;
99 : }
100 :
101 0 : room = write_room(line);
102 0 : len = (len > room) ? room : len;
103 :
104 0 : end = line->buffer + LINE_BUFSIZE - line->tail;
105 :
106 0 : if (len < end) {
107 0 : memcpy(line->tail, buf, len);
108 0 : line->tail += len;
109 : }
110 : else {
111 : /* The circular buffer is wrapping */
112 0 : memcpy(line->tail, buf, end);
113 0 : buf += end;
114 0 : memcpy(line->buffer, buf, len - end);
115 0 : line->tail = line->buffer + len - end;
116 : }
117 :
118 : return len;
119 : }
120 :
121 : /*
122 : * Flushes the ring buffer to the output channels. That is, write_chan is
123 : * called, passing it line->head as buffer, and an appropriate count.
124 : *
125 : * On exit, returns 1 when the buffer is empty,
126 : * 0 when the buffer is not empty on exit,
127 : * and -errno when an error occurred.
128 : *
129 : * Must be called while holding line->lock!*/
130 0 : static int flush_buffer(struct line *line)
131 : {
132 : int n, count;
133 :
134 0 : if ((line->buffer == NULL) || (line->head == line->tail))
135 : return 1;
136 :
137 0 : if (line->tail < line->head) {
138 : /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
139 0 : count = line->buffer + LINE_BUFSIZE - line->head;
140 :
141 0 : n = write_chan(line->chan_out, line->head, count,
142 0 : line->driver->write_irq);
143 0 : if (n < 0)
144 : return n;
145 0 : if (n == count) {
146 : /*
147 : * We have flushed from ->head to buffer end, now we
148 : * must flush only from the beginning to ->tail.
149 : */
150 0 : line->head = line->buffer;
151 : } else {
152 0 : line->head += n;
153 0 : return 0;
154 : }
155 : }
156 :
157 0 : count = line->tail - line->head;
158 0 : n = write_chan(line->chan_out, line->head, count,
159 0 : line->driver->write_irq);
160 :
161 0 : if (n < 0)
162 : return n;
163 :
164 0 : line->head += n;
165 0 : return line->head == line->tail;
166 : }
167 :
168 0 : void line_flush_buffer(struct tty_struct *tty)
169 : {
170 0 : struct line *line = tty->driver_data;
171 : unsigned long flags;
172 :
173 0 : spin_lock_irqsave(&line->lock, flags);
174 0 : flush_buffer(line);
175 0 : spin_unlock_irqrestore(&line->lock, flags);
176 0 : }
177 :
178 : /*
179 : * We map both ->flush_chars and ->put_char (which go in pair) onto
180 : * ->flush_buffer and ->write. Hope it's not that bad.
181 : */
182 0 : void line_flush_chars(struct tty_struct *tty)
183 : {
184 0 : line_flush_buffer(tty);
185 0 : }
186 :
187 0 : int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
188 : {
189 0 : struct line *line = tty->driver_data;
190 : unsigned long flags;
191 0 : int n, ret = 0;
192 :
193 0 : spin_lock_irqsave(&line->lock, flags);
194 0 : if (line->head != line->tail)
195 0 : ret = buffer_data(line, buf, len);
196 : else {
197 0 : n = write_chan(line->chan_out, buf, len,
198 0 : line->driver->write_irq);
199 0 : if (n < 0) {
200 : ret = n;
201 : goto out_up;
202 : }
203 :
204 0 : len -= n;
205 0 : ret += n;
206 0 : if (len > 0)
207 0 : ret += buffer_data(line, buf + n, len);
208 : }
209 : out_up:
210 0 : spin_unlock_irqrestore(&line->lock, flags);
211 0 : return ret;
212 : }
213 :
214 0 : void line_throttle(struct tty_struct *tty)
215 : {
216 0 : struct line *line = tty->driver_data;
217 :
218 0 : deactivate_chan(line->chan_in, line->driver->read_irq);
219 0 : line->throttled = 1;
220 0 : }
221 :
222 0 : void line_unthrottle(struct tty_struct *tty)
223 : {
224 0 : struct line *line = tty->driver_data;
225 :
226 0 : line->throttled = 0;
227 0 : chan_interrupt(line, line->driver->read_irq);
228 0 : }
229 :
230 0 : static irqreturn_t line_write_interrupt(int irq, void *data)
231 : {
232 0 : struct chan *chan = data;
233 0 : struct line *line = chan->line;
234 : int err;
235 :
236 : /*
237 : * Interrupts are disabled here because genirq keep irqs disabled when
238 : * calling the action handler.
239 : */
240 :
241 0 : spin_lock(&line->lock);
242 0 : err = flush_buffer(line);
243 0 : if (err == 0) {
244 0 : spin_unlock(&line->lock);
245 0 : return IRQ_NONE;
246 0 : } else if ((err < 0) && (err != -EAGAIN)) {
247 0 : line->head = line->buffer;
248 0 : line->tail = line->buffer;
249 : }
250 0 : spin_unlock(&line->lock);
251 :
252 0 : tty_port_tty_wakeup(&line->port);
253 :
254 0 : return IRQ_HANDLED;
255 : }
256 :
257 0 : int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
258 : {
259 0 : const struct line_driver *driver = line->driver;
260 : int err;
261 :
262 0 : if (input) {
263 0 : err = um_request_irq(driver->read_irq, fd, IRQ_READ,
264 : line_interrupt, IRQF_SHARED,
265 : driver->read_irq_name, data);
266 0 : if (err < 0)
267 : return err;
268 : }
269 :
270 0 : if (output) {
271 0 : err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
272 : line_write_interrupt, IRQF_SHARED,
273 : driver->write_irq_name, data);
274 0 : if (err < 0)
275 : return err;
276 : }
277 :
278 : return 0;
279 : }
280 :
281 0 : static int line_activate(struct tty_port *port, struct tty_struct *tty)
282 : {
283 : int ret;
284 0 : struct line *line = tty->driver_data;
285 :
286 0 : ret = enable_chan(line);
287 0 : if (ret)
288 : return ret;
289 :
290 0 : if (!line->sigio) {
291 0 : chan_enable_winch(line->chan_out, port);
292 0 : line->sigio = 1;
293 : }
294 :
295 0 : chan_window_size(line, &tty->winsize.ws_row,
296 : &tty->winsize.ws_col);
297 :
298 0 : return 0;
299 : }
300 :
301 : static void unregister_winch(struct tty_struct *tty);
302 :
303 0 : static void line_destruct(struct tty_port *port)
304 : {
305 0 : struct tty_struct *tty = tty_port_tty_get(port);
306 0 : struct line *line = tty->driver_data;
307 :
308 0 : if (line->sigio) {
309 0 : unregister_winch(tty);
310 0 : line->sigio = 0;
311 : }
312 0 : }
313 :
314 : static const struct tty_port_operations line_port_ops = {
315 : .activate = line_activate,
316 : .destruct = line_destruct,
317 : };
318 :
319 0 : int line_open(struct tty_struct *tty, struct file *filp)
320 : {
321 0 : struct line *line = tty->driver_data;
322 :
323 0 : return tty_port_open(&line->port, tty, filp);
324 : }
325 :
326 0 : int line_install(struct tty_driver *driver, struct tty_struct *tty,
327 : struct line *line)
328 : {
329 : int ret;
330 :
331 0 : ret = tty_standard_install(driver, tty);
332 0 : if (ret)
333 : return ret;
334 :
335 0 : tty->driver_data = line;
336 :
337 0 : return 0;
338 : }
339 :
340 0 : void line_close(struct tty_struct *tty, struct file * filp)
341 : {
342 0 : struct line *line = tty->driver_data;
343 :
344 0 : tty_port_close(&line->port, tty, filp);
345 0 : }
346 :
347 0 : void line_hangup(struct tty_struct *tty)
348 : {
349 0 : struct line *line = tty->driver_data;
350 :
351 0 : tty_port_hangup(&line->port);
352 0 : }
353 :
354 1 : void close_lines(struct line *lines, int nlines)
355 : {
356 : int i;
357 :
358 17 : for(i = 0; i < nlines; i++)
359 16 : close_chan(&lines[i]);
360 1 : }
361 :
362 16 : int setup_one_line(struct line *lines, int n, char *init,
363 : const struct chan_opts *opts, char **error_out)
364 : {
365 16 : struct line *line = &lines[n];
366 16 : struct tty_driver *driver = line->driver->driver;
367 16 : int err = -EINVAL;
368 :
369 16 : if (line->port.count) {
370 0 : *error_out = "Device is already open";
371 0 : goto out;
372 : }
373 :
374 16 : if (!strcmp(init, "none")) {
375 0 : if (line->valid) {
376 0 : line->valid = 0;
377 0 : kfree(line->init_str);
378 0 : tty_unregister_device(driver, n);
379 0 : parse_chan_pair(NULL, line, n, opts, error_out);
380 0 : err = 0;
381 : }
382 : } else {
383 16 : char *new = kstrdup(init, GFP_KERNEL);
384 16 : if (!new) {
385 0 : *error_out = "Failed to allocate memory";
386 0 : return -ENOMEM;
387 : }
388 16 : if (line->valid) {
389 0 : tty_unregister_device(driver, n);
390 0 : kfree(line->init_str);
391 : }
392 16 : line->init_str = new;
393 16 : line->valid = 1;
394 16 : err = parse_chan_pair(new, line, n, opts, error_out);
395 16 : if (!err) {
396 1 : struct device *d = tty_port_register_device(&line->port,
397 : driver, n, NULL);
398 1 : if (IS_ERR(d)) {
399 0 : *error_out = "Failed to register device";
400 0 : err = PTR_ERR(d);
401 0 : parse_chan_pair(NULL, line, n, opts, error_out);
402 : }
403 : }
404 16 : if (err) {
405 15 : line->init_str = NULL;
406 15 : line->valid = 0;
407 15 : kfree(new);
408 : }
409 : }
410 : out:
411 : return err;
412 : }
413 :
414 : /*
415 : * Common setup code for both startup command line and mconsole initialization.
416 : * @lines contains the array (of size @num) to modify;
417 : * @init is the setup string;
418 : * @error_out is an error string in the case of failure;
419 : */
420 :
421 0 : int line_setup(char **conf, unsigned int num, char **def,
422 : char *init, char *name)
423 : {
424 : char *error;
425 :
426 0 : if (*init == '=') {
427 : /*
428 : * We said con=/ssl= instead of con#=, so we are configuring all
429 : * consoles at once.
430 : */
431 0 : *def = init + 1;
432 : } else {
433 : char *end;
434 0 : unsigned n = simple_strtoul(init, &end, 0);
435 :
436 0 : if (*end != '=') {
437 : error = "Couldn't parse device number";
438 0 : goto out;
439 : }
440 0 : if (n >= num) {
441 : error = "Device number out of range";
442 : goto out;
443 : }
444 0 : conf[n] = end + 1;
445 : }
446 : return 0;
447 :
448 : out:
449 0 : printk(KERN_ERR "Failed to set up %s with "
450 : "configuration string \"%s\" : %s\n", name, init, error);
451 0 : return -EINVAL;
452 : }
453 :
454 0 : int line_config(struct line *lines, unsigned int num, char *str,
455 : const struct chan_opts *opts, char **error_out)
456 : {
457 : char *end;
458 : int n;
459 :
460 0 : if (*str == '=') {
461 0 : *error_out = "Can't configure all devices from mconsole";
462 0 : return -EINVAL;
463 : }
464 :
465 0 : n = simple_strtoul(str, &end, 0);
466 0 : if (*end++ != '=') {
467 0 : *error_out = "Couldn't parse device number";
468 0 : return -EINVAL;
469 : }
470 0 : if (n >= num) {
471 0 : *error_out = "Device number out of range";
472 0 : return -EINVAL;
473 : }
474 :
475 0 : return setup_one_line(lines, n, end, opts, error_out);
476 : }
477 :
478 0 : int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
479 : int size, char **error_out)
480 : {
481 : struct line *line;
482 : char *end;
483 0 : int dev, n = 0;
484 :
485 0 : dev = simple_strtoul(name, &end, 0);
486 0 : if ((*end != '\0') || (end == name)) {
487 0 : *error_out = "line_get_config failed to parse device number";
488 0 : return 0;
489 : }
490 :
491 0 : if ((dev < 0) || (dev >= num)) {
492 0 : *error_out = "device number out of range";
493 0 : return 0;
494 : }
495 :
496 0 : line = &lines[dev];
497 :
498 0 : if (!line->valid)
499 0 : CONFIG_CHUNK(str, size, n, "none", 1);
500 : else {
501 0 : struct tty_struct *tty = tty_port_tty_get(&line->port);
502 0 : if (tty == NULL) {
503 0 : CONFIG_CHUNK(str, size, n, line->init_str, 1);
504 : } else {
505 0 : n = chan_config_string(line, str, size, error_out);
506 0 : tty_kref_put(tty);
507 : }
508 : }
509 :
510 : return n;
511 : }
512 :
513 0 : int line_id(char **str, int *start_out, int *end_out)
514 : {
515 : char *end;
516 : int n;
517 :
518 0 : n = simple_strtoul(*str, &end, 0);
519 0 : if ((*end != '\0') || (end == *str))
520 : return -1;
521 :
522 0 : *str = end;
523 0 : *start_out = n;
524 0 : *end_out = n;
525 0 : return n;
526 : }
527 :
528 0 : int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
529 : {
530 0 : if (n >= num) {
531 0 : *error_out = "Device number out of range";
532 0 : return -EINVAL;
533 : }
534 0 : return setup_one_line(lines, n, "none", NULL, error_out);
535 : }
536 :
537 1 : int register_lines(struct line_driver *line_driver,
538 : const struct tty_operations *ops,
539 : struct line *lines, int nlines)
540 : {
541 : struct tty_driver *driver;
542 : int err;
543 : int i;
544 :
545 1 : driver = tty_alloc_driver(nlines, TTY_DRIVER_REAL_RAW |
546 : TTY_DRIVER_DYNAMIC_DEV);
547 1 : if (IS_ERR(driver))
548 0 : return PTR_ERR(driver);
549 :
550 1 : driver->driver_name = line_driver->name;
551 1 : driver->name = line_driver->device_name;
552 1 : driver->major = line_driver->major;
553 1 : driver->minor_start = line_driver->minor_start;
554 1 : driver->type = line_driver->type;
555 1 : driver->subtype = line_driver->subtype;
556 1 : driver->init_termios = tty_std_termios;
557 :
558 17 : for (i = 0; i < nlines; i++) {
559 16 : tty_port_init(&lines[i].port);
560 16 : lines[i].port.ops = &line_port_ops;
561 16 : spin_lock_init(&lines[i].lock);
562 16 : lines[i].driver = line_driver;
563 32 : INIT_LIST_HEAD(&lines[i].chan_list);
564 : }
565 2 : tty_set_operations(driver, ops);
566 :
567 1 : err = tty_register_driver(driver);
568 1 : if (err) {
569 0 : printk(KERN_ERR "register_lines : can't register %s driver\n",
570 : line_driver->name);
571 0 : tty_driver_kref_put(driver);
572 0 : for (i = 0; i < nlines; i++)
573 0 : tty_port_destroy(&lines[i].port);
574 : return err;
575 : }
576 :
577 1 : line_driver->driver = driver;
578 1 : mconsole_register_dev(&line_driver->mc);
579 1 : return 0;
580 : }
581 :
582 : static DEFINE_SPINLOCK(winch_handler_lock);
583 : static LIST_HEAD(winch_handlers);
584 :
585 : struct winch {
586 : struct list_head list;
587 : int fd;
588 : int tty_fd;
589 : int pid;
590 : struct tty_port *port;
591 : unsigned long stack;
592 : struct work_struct work;
593 : };
594 :
595 0 : static void __free_winch(struct work_struct *work)
596 : {
597 0 : struct winch *winch = container_of(work, struct winch, work);
598 0 : um_free_irq(WINCH_IRQ, winch);
599 :
600 0 : if (winch->pid != -1)
601 0 : os_kill_process(winch->pid, 1);
602 0 : if (winch->stack != 0)
603 0 : free_stack(winch->stack, 0);
604 0 : kfree(winch);
605 0 : }
606 :
607 0 : static void free_winch(struct winch *winch)
608 : {
609 0 : int fd = winch->fd;
610 0 : winch->fd = -1;
611 0 : if (fd != -1)
612 0 : os_close_file(fd);
613 0 : __free_winch(&winch->work);
614 0 : }
615 :
616 0 : static irqreturn_t winch_interrupt(int irq, void *data)
617 : {
618 0 : struct winch *winch = data;
619 : struct tty_struct *tty;
620 : struct line *line;
621 0 : int fd = winch->fd;
622 : int err;
623 : char c;
624 : struct pid *pgrp;
625 :
626 0 : if (fd != -1) {
627 0 : err = generic_read(fd, &c, NULL);
628 0 : if (err < 0) {
629 0 : if (err != -EAGAIN) {
630 0 : winch->fd = -1;
631 0 : list_del(&winch->list);
632 0 : os_close_file(fd);
633 0 : printk(KERN_ERR "winch_interrupt : "
634 : "read failed, errno = %d\n", -err);
635 0 : printk(KERN_ERR "fd %d is losing SIGWINCH "
636 : "support\n", winch->tty_fd);
637 0 : INIT_WORK(&winch->work, __free_winch);
638 0 : schedule_work(&winch->work);
639 0 : return IRQ_HANDLED;
640 : }
641 : goto out;
642 : }
643 : }
644 0 : tty = tty_port_tty_get(winch->port);
645 0 : if (tty != NULL) {
646 0 : line = tty->driver_data;
647 0 : if (line != NULL) {
648 0 : chan_window_size(line, &tty->winsize.ws_row,
649 : &tty->winsize.ws_col);
650 0 : pgrp = tty_get_pgrp(tty);
651 0 : if (pgrp)
652 0 : kill_pgrp(pgrp, SIGWINCH, 1);
653 0 : put_pid(pgrp);
654 : }
655 0 : tty_kref_put(tty);
656 : }
657 : out:
658 : return IRQ_HANDLED;
659 : }
660 :
661 0 : void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
662 : unsigned long stack)
663 : {
664 : struct winch *winch;
665 :
666 0 : winch = kmalloc(sizeof(*winch), GFP_KERNEL);
667 0 : if (winch == NULL) {
668 0 : printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
669 0 : goto cleanup;
670 : }
671 :
672 0 : *winch = ((struct winch) { .list = LIST_HEAD_INIT(winch->list),
673 : .fd = fd,
674 : .tty_fd = tty_fd,
675 : .pid = pid,
676 : .port = port,
677 : .stack = stack });
678 :
679 0 : if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
680 : IRQF_SHARED, "winch", winch) < 0) {
681 0 : printk(KERN_ERR "register_winch_irq - failed to register "
682 : "IRQ\n");
683 : goto out_free;
684 : }
685 :
686 0 : spin_lock(&winch_handler_lock);
687 0 : list_add(&winch->list, &winch_handlers);
688 : spin_unlock(&winch_handler_lock);
689 :
690 : return;
691 :
692 : out_free:
693 0 : kfree(winch);
694 : cleanup:
695 0 : os_kill_process(pid, 1);
696 0 : os_close_file(fd);
697 0 : if (stack != 0)
698 0 : free_stack(stack, 0);
699 : }
700 :
701 0 : static void unregister_winch(struct tty_struct *tty)
702 : {
703 : struct list_head *ele, *next;
704 : struct winch *winch;
705 : struct tty_struct *wtty;
706 :
707 0 : spin_lock(&winch_handler_lock);
708 :
709 0 : list_for_each_safe(ele, next, &winch_handlers) {
710 0 : winch = list_entry(ele, struct winch, list);
711 0 : wtty = tty_port_tty_get(winch->port);
712 0 : if (wtty == tty) {
713 0 : list_del(&winch->list);
714 0 : spin_unlock(&winch_handler_lock);
715 0 : free_winch(winch);
716 0 : break;
717 : }
718 0 : tty_kref_put(wtty);
719 : }
720 0 : spin_unlock(&winch_handler_lock);
721 0 : }
722 :
723 1 : static void winch_cleanup(void)
724 : {
725 : struct winch *winch;
726 :
727 : spin_lock(&winch_handler_lock);
728 1 : while ((winch = list_first_entry_or_null(&winch_handlers,
729 : struct winch, list))) {
730 0 : list_del(&winch->list);
731 0 : spin_unlock(&winch_handler_lock);
732 :
733 0 : free_winch(winch);
734 :
735 : spin_lock(&winch_handler_lock);
736 : }
737 :
738 1 : spin_unlock(&winch_handler_lock);
739 1 : }
740 : __uml_exitcall(winch_cleanup);
741 :
742 1 : char *add_xterm_umid(char *base)
743 : {
744 : char *umid, *title;
745 : int len;
746 :
747 1 : umid = get_umid();
748 1 : if (*umid == '\0')
749 : return base;
750 :
751 1 : len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
752 2 : title = kmalloc(len, GFP_KERNEL);
753 1 : if (title == NULL) {
754 0 : printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
755 0 : return base;
756 : }
757 :
758 1 : snprintf(title, len, "%s (%s)", base, umid);
759 1 : return title;
760 : }
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