ia64/linux-2.6.18-xen.hg

view drivers/char/n_tty.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
1 /*
2 * n_tty.c --- implements the N_TTY line discipline.
3 *
4 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
7 * anyway...)
8 *
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
11 * to N_TTY if it can not switch to any other line discipline.
12 *
13 * Written by Theodore Ts'o, Copyright 1994.
14 *
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
17 *
18 * This file may be redistributed under the terms of the GNU General Public
19 * License.
20 *
21 * Reduced memory usage for older ARM systems - Russell King.
22 *
23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
26 *
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where write_chan returns
30 * EAGAIN
31 */
33 #include <linux/types.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/signal.h>
37 #include <linux/fcntl.h>
38 #include <linux/sched.h>
39 #include <linux/interrupt.h>
40 #include <linux/tty.h>
41 #include <linux/timer.h>
42 #include <linux/ctype.h>
43 #include <linux/mm.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
49 #include <asm/uaccess.h>
50 #include <asm/system.h>
52 /* number of characters left in xmit buffer before select has we have room */
53 #define WAKEUP_CHARS 256
55 /*
56 * This defines the low- and high-watermarks for throttling and
57 * unthrottling the TTY driver. These watermarks are used for
58 * controlling the space in the read buffer.
59 */
60 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
61 #define TTY_THRESHOLD_UNTHROTTLE 128
63 static inline unsigned char *alloc_buf(void)
64 {
65 gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
67 if (PAGE_SIZE != N_TTY_BUF_SIZE)
68 return kmalloc(N_TTY_BUF_SIZE, prio);
69 else
70 return (unsigned char *)__get_free_page(prio);
71 }
73 static inline void free_buf(unsigned char *buf)
74 {
75 if (PAGE_SIZE != N_TTY_BUF_SIZE)
76 kfree(buf);
77 else
78 free_page((unsigned long) buf);
79 }
81 /**
82 * n_tty_set__room - receive space
83 * @tty: terminal
84 *
85 * Called by the driver to find out how much data it is
86 * permitted to feed to the line discipline without any being lost
87 * and thus to manage flow control. Not serialized. Answers for the
88 * "instant".
89 */
91 static void n_tty_set_room(struct tty_struct *tty)
92 {
93 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
95 /*
96 * If we are doing input canonicalization, and there are no
97 * pending newlines, let characters through without limit, so
98 * that erase characters will be handled. Other excess
99 * characters will be beeped.
100 */
101 if (left <= 0)
102 left = tty->icanon && !tty->canon_data;
103 tty->receive_room = left;
104 }
106 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
107 {
108 if (tty->read_cnt < N_TTY_BUF_SIZE) {
109 tty->read_buf[tty->read_head] = c;
110 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
111 tty->read_cnt++;
112 }
113 }
115 static void put_tty_queue(unsigned char c, struct tty_struct *tty)
116 {
117 unsigned long flags;
118 /*
119 * The problem of stomping on the buffers ends here.
120 * Why didn't anyone see this one coming? --AJK
121 */
122 spin_lock_irqsave(&tty->read_lock, flags);
123 put_tty_queue_nolock(c, tty);
124 spin_unlock_irqrestore(&tty->read_lock, flags);
125 }
127 /**
128 * check_unthrottle - allow new receive data
129 * @tty; tty device
130 *
131 * Check whether to call the driver.unthrottle function.
132 * We test the TTY_THROTTLED bit first so that it always
133 * indicates the current state. The decision about whether
134 * it is worth allowing more input has been taken by the caller.
135 * Can sleep, may be called under the atomic_read_lock mutex but
136 * this is not guaranteed.
137 */
139 static void check_unthrottle(struct tty_struct * tty)
140 {
141 if (tty->count &&
142 test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
143 tty->driver->unthrottle)
144 tty->driver->unthrottle(tty);
145 }
147 /**
148 * reset_buffer_flags - reset buffer state
149 * @tty: terminal to reset
150 *
151 * Reset the read buffer counters, clear the flags,
152 * and make sure the driver is unthrottled. Called
153 * from n_tty_open() and n_tty_flush_buffer().
154 */
155 static void reset_buffer_flags(struct tty_struct *tty)
156 {
157 unsigned long flags;
159 spin_lock_irqsave(&tty->read_lock, flags);
160 tty->read_head = tty->read_tail = tty->read_cnt = 0;
161 spin_unlock_irqrestore(&tty->read_lock, flags);
162 tty->canon_head = tty->canon_data = tty->erasing = 0;
163 memset(&tty->read_flags, 0, sizeof tty->read_flags);
164 n_tty_set_room(tty);
165 check_unthrottle(tty);
166 }
168 /**
169 * n_tty_flush_buffer - clean input queue
170 * @tty: terminal device
171 *
172 * Flush the input buffer. Called when the line discipline is
173 * being closed, when the tty layer wants the buffer flushed (eg
174 * at hangup) or when the N_TTY line discipline internally has to
175 * clean the pending queue (for example some signals).
176 *
177 * FIXME: tty->ctrl_status is not spinlocked and relies on
178 * lock_kernel() still.
179 */
181 static void n_tty_flush_buffer(struct tty_struct * tty)
182 {
183 /* clear everything and unthrottle the driver */
184 reset_buffer_flags(tty);
186 if (!tty->link)
187 return;
189 if (tty->link->packet) {
190 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
191 wake_up_interruptible(&tty->link->read_wait);
192 }
193 }
195 /**
196 * n_tty_chars_in_buffer - report available bytes
197 * @tty: tty device
198 *
199 * Report the number of characters buffered to be delivered to user
200 * at this instant in time.
201 */
203 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
204 {
205 unsigned long flags;
206 ssize_t n = 0;
208 spin_lock_irqsave(&tty->read_lock, flags);
209 if (!tty->icanon) {
210 n = tty->read_cnt;
211 } else if (tty->canon_data) {
212 n = (tty->canon_head > tty->read_tail) ?
213 tty->canon_head - tty->read_tail :
214 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
215 }
216 spin_unlock_irqrestore(&tty->read_lock, flags);
217 return n;
218 }
220 /**
221 * is_utf8_continuation - utf8 multibyte check
222 * @c: byte to check
223 *
224 * Returns true if the utf8 character 'c' is a multibyte continuation
225 * character. We use this to correctly compute the on screen size
226 * of the character when printing
227 */
229 static inline int is_utf8_continuation(unsigned char c)
230 {
231 return (c & 0xc0) == 0x80;
232 }
234 /**
235 * is_continuation - multibyte check
236 * @c: byte to check
237 *
238 * Returns true if the utf8 character 'c' is a multibyte continuation
239 * character and the terminal is in unicode mode.
240 */
242 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
243 {
244 return I_IUTF8(tty) && is_utf8_continuation(c);
245 }
247 /**
248 * opost - output post processor
249 * @c: character (or partial unicode symbol)
250 * @tty: terminal device
251 *
252 * Perform OPOST processing. Returns -1 when the output device is
253 * full and the character must be retried. Note that Linux currently
254 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
255 * relevant in the world today. If you ever need them, add them here.
256 *
257 * Called from both the receive and transmit sides and can be called
258 * re-entrantly. Relies on lock_kernel() still.
259 */
261 static int opost(unsigned char c, struct tty_struct *tty)
262 {
263 int space, spaces;
265 space = tty->driver->write_room(tty);
266 if (!space)
267 return -1;
269 if (O_OPOST(tty)) {
270 switch (c) {
271 case '\n':
272 if (O_ONLRET(tty))
273 tty->column = 0;
274 if (O_ONLCR(tty)) {
275 if (space < 2)
276 return -1;
277 tty->driver->put_char(tty, '\r');
278 tty->column = 0;
279 }
280 tty->canon_column = tty->column;
281 break;
282 case '\r':
283 if (O_ONOCR(tty) && tty->column == 0)
284 return 0;
285 if (O_OCRNL(tty)) {
286 c = '\n';
287 if (O_ONLRET(tty))
288 tty->canon_column = tty->column = 0;
289 break;
290 }
291 tty->canon_column = tty->column = 0;
292 break;
293 case '\t':
294 spaces = 8 - (tty->column & 7);
295 if (O_TABDLY(tty) == XTABS) {
296 if (space < spaces)
297 return -1;
298 tty->column += spaces;
299 tty->driver->write(tty, " ", spaces);
300 return 0;
301 }
302 tty->column += spaces;
303 break;
304 case '\b':
305 if (tty->column > 0)
306 tty->column--;
307 break;
308 default:
309 if (O_OLCUC(tty))
310 c = toupper(c);
311 if (!iscntrl(c) && !is_continuation(c, tty))
312 tty->column++;
313 break;
314 }
315 }
316 tty->driver->put_char(tty, c);
317 return 0;
318 }
320 /**
321 * opost_block - block postprocess
322 * @tty: terminal device
323 * @inbuf: user buffer
324 * @nr: number of bytes
325 *
326 * This path is used to speed up block console writes, among other
327 * things when processing blocks of output data. It handles only
328 * the simple cases normally found and helps to generate blocks of
329 * symbols for the console driver and thus improve performance.
330 *
331 * Called from write_chan under the tty layer write lock.
332 */
334 static ssize_t opost_block(struct tty_struct * tty,
335 const unsigned char * buf, unsigned int nr)
336 {
337 int space;
338 int i;
339 const unsigned char *cp;
341 space = tty->driver->write_room(tty);
342 if (!space)
343 return 0;
344 if (nr > space)
345 nr = space;
347 for (i = 0, cp = buf; i < nr; i++, cp++) {
348 switch (*cp) {
349 case '\n':
350 if (O_ONLRET(tty))
351 tty->column = 0;
352 if (O_ONLCR(tty))
353 goto break_out;
354 tty->canon_column = tty->column;
355 break;
356 case '\r':
357 if (O_ONOCR(tty) && tty->column == 0)
358 goto break_out;
359 if (O_OCRNL(tty))
360 goto break_out;
361 tty->canon_column = tty->column = 0;
362 break;
363 case '\t':
364 goto break_out;
365 case '\b':
366 if (tty->column > 0)
367 tty->column--;
368 break;
369 default:
370 if (O_OLCUC(tty))
371 goto break_out;
372 if (!iscntrl(*cp))
373 tty->column++;
374 break;
375 }
376 }
377 break_out:
378 if (tty->driver->flush_chars)
379 tty->driver->flush_chars(tty);
380 i = tty->driver->write(tty, buf, i);
381 return i;
382 }
385 /**
386 * put_char - write character to driver
387 * @c: character (or part of unicode symbol)
388 * @tty: terminal device
389 *
390 * Queue a byte to the driver layer for output
391 */
393 static inline void put_char(unsigned char c, struct tty_struct *tty)
394 {
395 tty->driver->put_char(tty, c);
396 }
398 /**
399 * echo_char - echo characters
400 * @c: unicode byte to echo
401 * @tty: terminal device
402 *
403 * Echo user input back onto the screen. This must be called only when
404 * L_ECHO(tty) is true. Called from the driver receive_buf path.
405 */
407 static void echo_char(unsigned char c, struct tty_struct *tty)
408 {
409 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
410 put_char('^', tty);
411 put_char(c ^ 0100, tty);
412 tty->column += 2;
413 } else
414 opost(c, tty);
415 }
417 static inline void finish_erasing(struct tty_struct *tty)
418 {
419 if (tty->erasing) {
420 put_char('/', tty);
421 tty->column++;
422 tty->erasing = 0;
423 }
424 }
426 /**
427 * eraser - handle erase function
428 * @c: character input
429 * @tty: terminal device
430 *
431 * Perform erase and neccessary output when an erase character is
432 * present in the stream from the driver layer. Handles the complexities
433 * of UTF-8 multibyte symbols.
434 */
436 static void eraser(unsigned char c, struct tty_struct *tty)
437 {
438 enum { ERASE, WERASE, KILL } kill_type;
439 int head, seen_alnums, cnt;
440 unsigned long flags;
442 if (tty->read_head == tty->canon_head) {
443 /* opost('\a', tty); */ /* what do you think? */
444 return;
445 }
446 if (c == ERASE_CHAR(tty))
447 kill_type = ERASE;
448 else if (c == WERASE_CHAR(tty))
449 kill_type = WERASE;
450 else {
451 if (!L_ECHO(tty)) {
452 spin_lock_irqsave(&tty->read_lock, flags);
453 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
454 (N_TTY_BUF_SIZE - 1));
455 tty->read_head = tty->canon_head;
456 spin_unlock_irqrestore(&tty->read_lock, flags);
457 return;
458 }
459 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
460 spin_lock_irqsave(&tty->read_lock, flags);
461 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
462 (N_TTY_BUF_SIZE - 1));
463 tty->read_head = tty->canon_head;
464 spin_unlock_irqrestore(&tty->read_lock, flags);
465 finish_erasing(tty);
466 echo_char(KILL_CHAR(tty), tty);
467 /* Add a newline if ECHOK is on and ECHOKE is off. */
468 if (L_ECHOK(tty))
469 opost('\n', tty);
470 return;
471 }
472 kill_type = KILL;
473 }
475 seen_alnums = 0;
476 while (tty->read_head != tty->canon_head) {
477 head = tty->read_head;
479 /* erase a single possibly multibyte character */
480 do {
481 head = (head - 1) & (N_TTY_BUF_SIZE-1);
482 c = tty->read_buf[head];
483 } while (is_continuation(c, tty) && head != tty->canon_head);
485 /* do not partially erase */
486 if (is_continuation(c, tty))
487 break;
489 if (kill_type == WERASE) {
490 /* Equivalent to BSD's ALTWERASE. */
491 if (isalnum(c) || c == '_')
492 seen_alnums++;
493 else if (seen_alnums)
494 break;
495 }
496 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
497 spin_lock_irqsave(&tty->read_lock, flags);
498 tty->read_head = head;
499 tty->read_cnt -= cnt;
500 spin_unlock_irqrestore(&tty->read_lock, flags);
501 if (L_ECHO(tty)) {
502 if (L_ECHOPRT(tty)) {
503 if (!tty->erasing) {
504 put_char('\\', tty);
505 tty->column++;
506 tty->erasing = 1;
507 }
508 /* if cnt > 1, output a multi-byte character */
509 echo_char(c, tty);
510 while (--cnt > 0) {
511 head = (head+1) & (N_TTY_BUF_SIZE-1);
512 put_char(tty->read_buf[head], tty);
513 }
514 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
515 echo_char(ERASE_CHAR(tty), tty);
516 } else if (c == '\t') {
517 unsigned int col = tty->canon_column;
518 unsigned long tail = tty->canon_head;
520 /* Find the column of the last char. */
521 while (tail != tty->read_head) {
522 c = tty->read_buf[tail];
523 if (c == '\t')
524 col = (col | 7) + 1;
525 else if (iscntrl(c)) {
526 if (L_ECHOCTL(tty))
527 col += 2;
528 } else if (!is_continuation(c, tty))
529 col++;
530 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
531 }
533 /* should never happen */
534 if (tty->column > 0x80000000)
535 tty->column = 0;
537 /* Now backup to that column. */
538 while (tty->column > col) {
539 /* Can't use opost here. */
540 put_char('\b', tty);
541 if (tty->column > 0)
542 tty->column--;
543 }
544 } else {
545 if (iscntrl(c) && L_ECHOCTL(tty)) {
546 put_char('\b', tty);
547 put_char(' ', tty);
548 put_char('\b', tty);
549 if (tty->column > 0)
550 tty->column--;
551 }
552 if (!iscntrl(c) || L_ECHOCTL(tty)) {
553 put_char('\b', tty);
554 put_char(' ', tty);
555 put_char('\b', tty);
556 if (tty->column > 0)
557 tty->column--;
558 }
559 }
560 }
561 if (kill_type == ERASE)
562 break;
563 }
564 if (tty->read_head == tty->canon_head)
565 finish_erasing(tty);
566 }
568 /**
569 * isig - handle the ISIG optio
570 * @sig: signal
571 * @tty: terminal
572 * @flush: force flush
573 *
574 * Called when a signal is being sent due to terminal input. This
575 * may caus terminal flushing to take place according to the termios
576 * settings and character used. Called from the driver receive_buf
577 * path so serialized.
578 */
580 static inline void isig(int sig, struct tty_struct *tty, int flush)
581 {
582 if (tty->pgrp > 0)
583 kill_pg(tty->pgrp, sig, 1);
584 if (flush || !L_NOFLSH(tty)) {
585 n_tty_flush_buffer(tty);
586 if (tty->driver->flush_buffer)
587 tty->driver->flush_buffer(tty);
588 }
589 }
591 /**
592 * n_tty_receive_break - handle break
593 * @tty: terminal
594 *
595 * An RS232 break event has been hit in the incoming bitstream. This
596 * can cause a variety of events depending upon the termios settings.
597 *
598 * Called from the receive_buf path so single threaded.
599 */
601 static inline void n_tty_receive_break(struct tty_struct *tty)
602 {
603 if (I_IGNBRK(tty))
604 return;
605 if (I_BRKINT(tty)) {
606 isig(SIGINT, tty, 1);
607 return;
608 }
609 if (I_PARMRK(tty)) {
610 put_tty_queue('\377', tty);
611 put_tty_queue('\0', tty);
612 }
613 put_tty_queue('\0', tty);
614 wake_up_interruptible(&tty->read_wait);
615 }
617 /**
618 * n_tty_receive_overrun - handle overrun reporting
619 * @tty: terminal
620 *
621 * Data arrived faster than we could process it. While the tty
622 * driver has flagged this the bits that were missed are gone
623 * forever.
624 *
625 * Called from the receive_buf path so single threaded. Does not
626 * need locking as num_overrun and overrun_time are function
627 * private.
628 */
630 static inline void n_tty_receive_overrun(struct tty_struct *tty)
631 {
632 char buf[64];
634 tty->num_overrun++;
635 if (time_before(tty->overrun_time, jiffies - HZ) ||
636 time_after(tty->overrun_time, jiffies)) {
637 printk(KERN_WARNING "%s: %d input overrun(s)\n",
638 tty_name(tty, buf),
639 tty->num_overrun);
640 tty->overrun_time = jiffies;
641 tty->num_overrun = 0;
642 }
643 }
645 /**
646 * n_tty_receive_parity_error - error notifier
647 * @tty: terminal device
648 * @c: character
649 *
650 * Process a parity error and queue the right data to indicate
651 * the error case if neccessary. Locking as per n_tty_receive_buf.
652 */
653 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
654 unsigned char c)
655 {
656 if (I_IGNPAR(tty)) {
657 return;
658 }
659 if (I_PARMRK(tty)) {
660 put_tty_queue('\377', tty);
661 put_tty_queue('\0', tty);
662 put_tty_queue(c, tty);
663 } else if (I_INPCK(tty))
664 put_tty_queue('\0', tty);
665 else
666 put_tty_queue(c, tty);
667 wake_up_interruptible(&tty->read_wait);
668 }
670 /**
671 * n_tty_receive_char - perform processing
672 * @tty: terminal device
673 * @c: character
674 *
675 * Process an individual character of input received from the driver.
676 * This is serialized with respect to itself by the rules for the
677 * driver above.
678 */
680 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
681 {
682 unsigned long flags;
684 if (tty->raw) {
685 put_tty_queue(c, tty);
686 return;
687 }
689 if (tty->stopped && !tty->flow_stopped &&
690 I_IXON(tty) && I_IXANY(tty)) {
691 start_tty(tty);
692 return;
693 }
695 if (I_ISTRIP(tty))
696 c &= 0x7f;
697 if (I_IUCLC(tty) && L_IEXTEN(tty))
698 c=tolower(c);
700 if (tty->closing) {
701 if (I_IXON(tty)) {
702 if (c == START_CHAR(tty))
703 start_tty(tty);
704 else if (c == STOP_CHAR(tty))
705 stop_tty(tty);
706 }
707 return;
708 }
710 /*
711 * If the previous character was LNEXT, or we know that this
712 * character is not one of the characters that we'll have to
713 * handle specially, do shortcut processing to speed things
714 * up.
715 */
716 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
717 finish_erasing(tty);
718 tty->lnext = 0;
719 if (L_ECHO(tty)) {
720 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
721 put_char('\a', tty); /* beep if no space */
722 return;
723 }
724 /* Record the column of first canon char. */
725 if (tty->canon_head == tty->read_head)
726 tty->canon_column = tty->column;
727 echo_char(c, tty);
728 }
729 if (I_PARMRK(tty) && c == (unsigned char) '\377')
730 put_tty_queue(c, tty);
731 put_tty_queue(c, tty);
732 return;
733 }
735 if (c == '\r') {
736 if (I_IGNCR(tty))
737 return;
738 if (I_ICRNL(tty))
739 c = '\n';
740 } else if (c == '\n' && I_INLCR(tty))
741 c = '\r';
742 if (I_IXON(tty)) {
743 if (c == START_CHAR(tty)) {
744 start_tty(tty);
745 return;
746 }
747 if (c == STOP_CHAR(tty)) {
748 stop_tty(tty);
749 return;
750 }
751 }
752 if (L_ISIG(tty)) {
753 int signal;
754 signal = SIGINT;
755 if (c == INTR_CHAR(tty))
756 goto send_signal;
757 signal = SIGQUIT;
758 if (c == QUIT_CHAR(tty))
759 goto send_signal;
760 signal = SIGTSTP;
761 if (c == SUSP_CHAR(tty)) {
762 send_signal:
763 isig(signal, tty, 0);
764 return;
765 }
766 }
767 if (tty->icanon) {
768 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
769 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
770 eraser(c, tty);
771 return;
772 }
773 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
774 tty->lnext = 1;
775 if (L_ECHO(tty)) {
776 finish_erasing(tty);
777 if (L_ECHOCTL(tty)) {
778 put_char('^', tty);
779 put_char('\b', tty);
780 }
781 }
782 return;
783 }
784 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
785 L_IEXTEN(tty)) {
786 unsigned long tail = tty->canon_head;
788 finish_erasing(tty);
789 echo_char(c, tty);
790 opost('\n', tty);
791 while (tail != tty->read_head) {
792 echo_char(tty->read_buf[tail], tty);
793 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
794 }
795 return;
796 }
797 if (c == '\n') {
798 if (L_ECHO(tty) || L_ECHONL(tty)) {
799 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
800 put_char('\a', tty);
801 opost('\n', tty);
802 }
803 goto handle_newline;
804 }
805 if (c == EOF_CHAR(tty)) {
806 if (tty->canon_head != tty->read_head)
807 set_bit(TTY_PUSH, &tty->flags);
808 c = __DISABLED_CHAR;
809 goto handle_newline;
810 }
811 if ((c == EOL_CHAR(tty)) ||
812 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
813 /*
814 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
815 */
816 if (L_ECHO(tty)) {
817 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
818 put_char('\a', tty);
819 /* Record the column of first canon char. */
820 if (tty->canon_head == tty->read_head)
821 tty->canon_column = tty->column;
822 echo_char(c, tty);
823 }
824 /*
825 * XXX does PARMRK doubling happen for
826 * EOL_CHAR and EOL2_CHAR?
827 */
828 if (I_PARMRK(tty) && c == (unsigned char) '\377')
829 put_tty_queue(c, tty);
831 handle_newline:
832 spin_lock_irqsave(&tty->read_lock, flags);
833 set_bit(tty->read_head, tty->read_flags);
834 put_tty_queue_nolock(c, tty);
835 tty->canon_head = tty->read_head;
836 tty->canon_data++;
837 spin_unlock_irqrestore(&tty->read_lock, flags);
838 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
839 if (waitqueue_active(&tty->read_wait))
840 wake_up_interruptible(&tty->read_wait);
841 return;
842 }
843 }
845 finish_erasing(tty);
846 if (L_ECHO(tty)) {
847 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
848 put_char('\a', tty); /* beep if no space */
849 return;
850 }
851 if (c == '\n')
852 opost('\n', tty);
853 else {
854 /* Record the column of first canon char. */
855 if (tty->canon_head == tty->read_head)
856 tty->canon_column = tty->column;
857 echo_char(c, tty);
858 }
859 }
861 if (I_PARMRK(tty) && c == (unsigned char) '\377')
862 put_tty_queue(c, tty);
864 put_tty_queue(c, tty);
865 }
868 /**
869 * n_tty_write_wakeup - asynchronous I/O notifier
870 * @tty: tty device
871 *
872 * Required for the ptys, serial driver etc. since processes
873 * that attach themselves to the master and rely on ASYNC
874 * IO must be woken up
875 */
877 static void n_tty_write_wakeup(struct tty_struct *tty)
878 {
879 if (tty->fasync)
880 {
881 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
882 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
883 }
884 return;
885 }
887 /**
888 * n_tty_receive_buf - data receive
889 * @tty: terminal device
890 * @cp: buffer
891 * @fp: flag buffer
892 * @count: characters
893 *
894 * Called by the terminal driver when a block of characters has
895 * been received. This function must be called from soft contexts
896 * not from interrupt context. The driver is responsible for making
897 * calls one at a time and in order (or using flush_to_ldisc)
898 */
900 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
901 char *fp, int count)
902 {
903 const unsigned char *p;
904 char *f, flags = TTY_NORMAL;
905 int i;
906 char buf[64];
907 unsigned long cpuflags;
909 if (!tty->read_buf)
910 return;
912 if (tty->real_raw) {
913 spin_lock_irqsave(&tty->read_lock, cpuflags);
914 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
915 N_TTY_BUF_SIZE - tty->read_head);
916 i = min(count, i);
917 memcpy(tty->read_buf + tty->read_head, cp, i);
918 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
919 tty->read_cnt += i;
920 cp += i;
921 count -= i;
923 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
924 N_TTY_BUF_SIZE - tty->read_head);
925 i = min(count, i);
926 memcpy(tty->read_buf + tty->read_head, cp, i);
927 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
928 tty->read_cnt += i;
929 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
930 } else {
931 for (i=count, p = cp, f = fp; i; i--, p++) {
932 if (f)
933 flags = *f++;
934 switch (flags) {
935 case TTY_NORMAL:
936 n_tty_receive_char(tty, *p);
937 break;
938 case TTY_BREAK:
939 n_tty_receive_break(tty);
940 break;
941 case TTY_PARITY:
942 case TTY_FRAME:
943 n_tty_receive_parity_error(tty, *p);
944 break;
945 case TTY_OVERRUN:
946 n_tty_receive_overrun(tty);
947 break;
948 default:
949 printk("%s: unknown flag %d\n",
950 tty_name(tty, buf), flags);
951 break;
952 }
953 }
954 if (tty->driver->flush_chars)
955 tty->driver->flush_chars(tty);
956 }
958 n_tty_set_room(tty);
960 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
961 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
962 if (waitqueue_active(&tty->read_wait))
963 wake_up_interruptible(&tty->read_wait);
964 }
966 /*
967 * Check the remaining room for the input canonicalization
968 * mode. We don't want to throttle the driver if we're in
969 * canonical mode and don't have a newline yet!
970 */
971 if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
972 /* check TTY_THROTTLED first so it indicates our state */
973 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
974 tty->driver->throttle)
975 tty->driver->throttle(tty);
976 }
977 }
979 int is_ignored(int sig)
980 {
981 return (sigismember(&current->blocked, sig) ||
982 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
983 }
985 /**
986 * n_tty_set_termios - termios data changed
987 * @tty: terminal
988 * @old: previous data
989 *
990 * Called by the tty layer when the user changes termios flags so
991 * that the line discipline can plan ahead. This function cannot sleep
992 * and is protected from re-entry by the tty layer. The user is
993 * guaranteed that this function will not be re-entered or in progress
994 * when the ldisc is closed.
995 */
997 static void n_tty_set_termios(struct tty_struct *tty, struct termios * old)
998 {
999 if (!tty)
1000 return;
1002 tty->icanon = (L_ICANON(tty) != 0);
1003 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1004 tty->raw = 1;
1005 tty->real_raw = 1;
1006 n_tty_set_room(tty);
1007 return;
1009 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1010 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1011 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1012 I_PARMRK(tty)) {
1013 memset(tty->process_char_map, 0, 256/8);
1015 if (I_IGNCR(tty) || I_ICRNL(tty))
1016 set_bit('\r', tty->process_char_map);
1017 if (I_INLCR(tty))
1018 set_bit('\n', tty->process_char_map);
1020 if (L_ICANON(tty)) {
1021 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1022 set_bit(KILL_CHAR(tty), tty->process_char_map);
1023 set_bit(EOF_CHAR(tty), tty->process_char_map);
1024 set_bit('\n', tty->process_char_map);
1025 set_bit(EOL_CHAR(tty), tty->process_char_map);
1026 if (L_IEXTEN(tty)) {
1027 set_bit(WERASE_CHAR(tty),
1028 tty->process_char_map);
1029 set_bit(LNEXT_CHAR(tty),
1030 tty->process_char_map);
1031 set_bit(EOL2_CHAR(tty),
1032 tty->process_char_map);
1033 if (L_ECHO(tty))
1034 set_bit(REPRINT_CHAR(tty),
1035 tty->process_char_map);
1038 if (I_IXON(tty)) {
1039 set_bit(START_CHAR(tty), tty->process_char_map);
1040 set_bit(STOP_CHAR(tty), tty->process_char_map);
1042 if (L_ISIG(tty)) {
1043 set_bit(INTR_CHAR(tty), tty->process_char_map);
1044 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1045 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1047 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1048 tty->raw = 0;
1049 tty->real_raw = 0;
1050 } else {
1051 tty->raw = 1;
1052 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1053 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1054 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1055 tty->real_raw = 1;
1056 else
1057 tty->real_raw = 0;
1059 n_tty_set_room(tty);
1062 /**
1063 * n_tty_close - close the ldisc for this tty
1064 * @tty: device
1066 * Called from the terminal layer when this line discipline is
1067 * being shut down, either because of a close or becsuse of a
1068 * discipline change. The function will not be called while other
1069 * ldisc methods are in progress.
1070 */
1072 static void n_tty_close(struct tty_struct *tty)
1074 n_tty_flush_buffer(tty);
1075 if (tty->read_buf) {
1076 free_buf(tty->read_buf);
1077 tty->read_buf = NULL;
1081 /**
1082 * n_tty_open - open an ldisc
1083 * @tty: terminal to open
1085 * Called when this line discipline is being attached to the
1086 * terminal device. Can sleep. Called serialized so that no
1087 * other events will occur in parallel. No further open will occur
1088 * until a close.
1089 */
1091 static int n_tty_open(struct tty_struct *tty)
1093 if (!tty)
1094 return -EINVAL;
1096 /* This one is ugly. Currently a malloc failure here can panic */
1097 if (!tty->read_buf) {
1098 tty->read_buf = alloc_buf();
1099 if (!tty->read_buf)
1100 return -ENOMEM;
1102 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1103 reset_buffer_flags(tty);
1104 tty->column = 0;
1105 n_tty_set_termios(tty, NULL);
1106 tty->minimum_to_wake = 1;
1107 tty->closing = 0;
1108 return 0;
1111 static inline int input_available_p(struct tty_struct *tty, int amt)
1113 if (tty->icanon) {
1114 if (tty->canon_data)
1115 return 1;
1116 } else if (tty->read_cnt >= (amt ? amt : 1))
1117 return 1;
1119 return 0;
1122 /**
1123 * copy_from_read_buf - copy read data directly
1124 * @tty: terminal device
1125 * @b: user data
1126 * @nr: size of data
1128 * Helper function to speed up read_chan. It is only called when
1129 * ICANON is off; it copies characters straight from the tty queue to
1130 * user space directly. It can be profitably called twice; once to
1131 * drain the space from the tail pointer to the (physical) end of the
1132 * buffer, and once to drain the space from the (physical) beginning of
1133 * the buffer to head pointer.
1135 * Called under the tty->atomic_read_lock sem
1137 */
1139 static int copy_from_read_buf(struct tty_struct *tty,
1140 unsigned char __user **b,
1141 size_t *nr)
1144 int retval;
1145 size_t n;
1146 unsigned long flags;
1148 retval = 0;
1149 spin_lock_irqsave(&tty->read_lock, flags);
1150 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1151 n = min(*nr, n);
1152 spin_unlock_irqrestore(&tty->read_lock, flags);
1153 if (n) {
1154 mb();
1155 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1156 n -= retval;
1157 spin_lock_irqsave(&tty->read_lock, flags);
1158 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1159 tty->read_cnt -= n;
1160 spin_unlock_irqrestore(&tty->read_lock, flags);
1161 *b += n;
1162 *nr -= n;
1164 return retval;
1167 extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *);
1169 /**
1170 * job_control - check job control
1171 * @tty: tty
1172 * @file: file handle
1174 * Perform job control management checks on this file/tty descriptor
1175 * and if appropriate send any needed signals and return a negative
1176 * error code if action should be taken.
1177 */
1179 static int job_control(struct tty_struct *tty, struct file *file)
1181 /* Job control check -- must be done at start and after
1182 every sleep (POSIX.1 7.1.1.4). */
1183 /* NOTE: not yet done after every sleep pending a thorough
1184 check of the logic of this change. -- jlc */
1185 /* don't stop on /dev/console */
1186 if (file->f_op->write != redirected_tty_write &&
1187 current->signal->tty == tty) {
1188 if (tty->pgrp <= 0)
1189 printk("read_chan: tty->pgrp <= 0!\n");
1190 else if (process_group(current) != tty->pgrp) {
1191 if (is_ignored(SIGTTIN) ||
1192 is_orphaned_pgrp(process_group(current)))
1193 return -EIO;
1194 kill_pg(process_group(current), SIGTTIN, 1);
1195 return -ERESTARTSYS;
1198 return 0;
1202 /**
1203 * read_chan - read function for tty
1204 * @tty: tty device
1205 * @file: file object
1206 * @buf: userspace buffer pointer
1207 * @nr: size of I/O
1209 * Perform reads for the line discipline. We are guaranteed that the
1210 * line discipline will not be closed under us but we may get multiple
1211 * parallel readers and must handle this ourselves. We may also get
1212 * a hangup. Always called in user context, may sleep.
1214 * This code must be sure never to sleep through a hangup.
1215 */
1217 static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1218 unsigned char __user *buf, size_t nr)
1220 unsigned char __user *b = buf;
1221 DECLARE_WAITQUEUE(wait, current);
1222 int c;
1223 int minimum, time;
1224 ssize_t retval = 0;
1225 ssize_t size;
1226 long timeout;
1227 unsigned long flags;
1229 do_it_again:
1231 if (!tty->read_buf) {
1232 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
1233 return -EIO;
1236 c = job_control(tty, file);
1237 if(c < 0)
1238 return c;
1240 minimum = time = 0;
1241 timeout = MAX_SCHEDULE_TIMEOUT;
1242 if (!tty->icanon) {
1243 time = (HZ / 10) * TIME_CHAR(tty);
1244 minimum = MIN_CHAR(tty);
1245 if (minimum) {
1246 if (time)
1247 tty->minimum_to_wake = 1;
1248 else if (!waitqueue_active(&tty->read_wait) ||
1249 (tty->minimum_to_wake > minimum))
1250 tty->minimum_to_wake = minimum;
1251 } else {
1252 timeout = 0;
1253 if (time) {
1254 timeout = time;
1255 time = 0;
1257 tty->minimum_to_wake = minimum = 1;
1261 /*
1262 * Internal serialization of reads.
1263 */
1264 if (file->f_flags & O_NONBLOCK) {
1265 if (!mutex_trylock(&tty->atomic_read_lock))
1266 return -EAGAIN;
1268 else {
1269 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1270 return -ERESTARTSYS;
1273 add_wait_queue(&tty->read_wait, &wait);
1274 while (nr) {
1275 /* First test for status change. */
1276 if (tty->packet && tty->link->ctrl_status) {
1277 unsigned char cs;
1278 if (b != buf)
1279 break;
1280 cs = tty->link->ctrl_status;
1281 tty->link->ctrl_status = 0;
1282 if (put_user(cs, b++)) {
1283 retval = -EFAULT;
1284 b--;
1285 break;
1287 nr--;
1288 break;
1290 /* This statement must be first before checking for input
1291 so that any interrupt will set the state back to
1292 TASK_RUNNING. */
1293 set_current_state(TASK_INTERRUPTIBLE);
1295 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1296 ((minimum - (b - buf)) >= 1))
1297 tty->minimum_to_wake = (minimum - (b - buf));
1299 if (!input_available_p(tty, 0)) {
1300 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1301 retval = -EIO;
1302 break;
1304 if (tty_hung_up_p(file))
1305 break;
1306 if (!timeout)
1307 break;
1308 if (file->f_flags & O_NONBLOCK) {
1309 retval = -EAGAIN;
1310 break;
1312 if (signal_pending(current)) {
1313 retval = -ERESTARTSYS;
1314 break;
1316 n_tty_set_room(tty);
1317 timeout = schedule_timeout(timeout);
1318 continue;
1320 __set_current_state(TASK_RUNNING);
1322 /* Deal with packet mode. */
1323 if (tty->packet && b == buf) {
1324 if (put_user(TIOCPKT_DATA, b++)) {
1325 retval = -EFAULT;
1326 b--;
1327 break;
1329 nr--;
1332 if (tty->icanon) {
1333 /* N.B. avoid overrun if nr == 0 */
1334 while (nr && tty->read_cnt) {
1335 int eol;
1337 eol = test_and_clear_bit(tty->read_tail,
1338 tty->read_flags);
1339 c = tty->read_buf[tty->read_tail];
1340 spin_lock_irqsave(&tty->read_lock, flags);
1341 tty->read_tail = ((tty->read_tail+1) &
1342 (N_TTY_BUF_SIZE-1));
1343 tty->read_cnt--;
1344 if (eol) {
1345 /* this test should be redundant:
1346 * we shouldn't be reading data if
1347 * canon_data is 0
1348 */
1349 if (--tty->canon_data < 0)
1350 tty->canon_data = 0;
1352 spin_unlock_irqrestore(&tty->read_lock, flags);
1354 if (!eol || (c != __DISABLED_CHAR)) {
1355 if (put_user(c, b++)) {
1356 retval = -EFAULT;
1357 b--;
1358 break;
1360 nr--;
1362 if (eol)
1363 break;
1365 if (retval)
1366 break;
1367 } else {
1368 int uncopied;
1369 uncopied = copy_from_read_buf(tty, &b, &nr);
1370 uncopied += copy_from_read_buf(tty, &b, &nr);
1371 if (uncopied) {
1372 retval = -EFAULT;
1373 break;
1377 /* If there is enough space in the read buffer now, let the
1378 * low-level driver know. We use n_tty_chars_in_buffer() to
1379 * check the buffer, as it now knows about canonical mode.
1380 * Otherwise, if the driver is throttled and the line is
1381 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1382 * we won't get any more characters.
1383 */
1384 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1385 n_tty_set_room(tty);
1386 check_unthrottle(tty);
1389 if (b - buf >= minimum)
1390 break;
1391 if (time)
1392 timeout = time;
1394 mutex_unlock(&tty->atomic_read_lock);
1395 remove_wait_queue(&tty->read_wait, &wait);
1397 if (!waitqueue_active(&tty->read_wait))
1398 tty->minimum_to_wake = minimum;
1400 __set_current_state(TASK_RUNNING);
1401 size = b - buf;
1402 if (size) {
1403 retval = size;
1404 if (nr)
1405 clear_bit(TTY_PUSH, &tty->flags);
1406 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1407 goto do_it_again;
1409 n_tty_set_room(tty);
1411 return retval;
1414 /**
1415 * write_chan - write function for tty
1416 * @tty: tty device
1417 * @file: file object
1418 * @buf: userspace buffer pointer
1419 * @nr: size of I/O
1421 * Write function of the terminal device. This is serialized with
1422 * respect to other write callers but not to termios changes, reads
1423 * and other such events. We must be careful with N_TTY as the receive
1424 * code will echo characters, thus calling driver write methods.
1426 * This code must be sure never to sleep through a hangup.
1427 */
1429 static ssize_t write_chan(struct tty_struct * tty, struct file * file,
1430 const unsigned char * buf, size_t nr)
1432 const unsigned char *b = buf;
1433 DECLARE_WAITQUEUE(wait, current);
1434 int c;
1435 ssize_t retval = 0;
1437 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1438 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1439 retval = tty_check_change(tty);
1440 if (retval)
1441 return retval;
1444 add_wait_queue(&tty->write_wait, &wait);
1445 while (1) {
1446 set_current_state(TASK_INTERRUPTIBLE);
1447 if (signal_pending(current)) {
1448 retval = -ERESTARTSYS;
1449 break;
1451 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1452 retval = -EIO;
1453 break;
1455 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1456 while (nr > 0) {
1457 ssize_t num = opost_block(tty, b, nr);
1458 if (num < 0) {
1459 if (num == -EAGAIN)
1460 break;
1461 retval = num;
1462 goto break_out;
1464 b += num;
1465 nr -= num;
1466 if (nr == 0)
1467 break;
1468 c = *b;
1469 if (opost(c, tty) < 0)
1470 break;
1471 b++; nr--;
1473 if (tty->driver->flush_chars)
1474 tty->driver->flush_chars(tty);
1475 } else {
1476 while (nr > 0) {
1477 c = tty->driver->write(tty, b, nr);
1478 if (c < 0) {
1479 retval = c;
1480 goto break_out;
1482 if (!c)
1483 break;
1484 b += c;
1485 nr -= c;
1488 if (!nr)
1489 break;
1490 if (file->f_flags & O_NONBLOCK) {
1491 retval = -EAGAIN;
1492 break;
1494 schedule();
1496 break_out:
1497 __set_current_state(TASK_RUNNING);
1498 remove_wait_queue(&tty->write_wait, &wait);
1499 return (b - buf) ? b - buf : retval;
1502 /**
1503 * normal_poll - poll method for N_TTY
1504 * @tty: terminal device
1505 * @file: file accessing it
1506 * @wait: poll table
1508 * Called when the line discipline is asked to poll() for data or
1509 * for special events. This code is not serialized with respect to
1510 * other events save open/close.
1512 * This code must be sure never to sleep through a hangup.
1513 * Called without the kernel lock held - fine
1515 * FIXME: if someone changes the VMIN or discipline settings for the
1516 * terminal while another process is in poll() the poll does not
1517 * recompute the new limits. Possibly set_termios should issue
1518 * a read wakeup to fix this bug.
1519 */
1521 static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
1523 unsigned int mask = 0;
1525 poll_wait(file, &tty->read_wait, wait);
1526 poll_wait(file, &tty->write_wait, wait);
1527 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1528 mask |= POLLIN | POLLRDNORM;
1529 if (tty->packet && tty->link->ctrl_status)
1530 mask |= POLLPRI | POLLIN | POLLRDNORM;
1531 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1532 mask |= POLLHUP;
1533 if (tty_hung_up_p(file))
1534 mask |= POLLHUP;
1535 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1536 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1537 tty->minimum_to_wake = MIN_CHAR(tty);
1538 else
1539 tty->minimum_to_wake = 1;
1541 if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
1542 tty->driver->write_room(tty) > 0)
1543 mask |= POLLOUT | POLLWRNORM;
1544 return mask;
1547 struct tty_ldisc tty_ldisc_N_TTY = {
1548 TTY_LDISC_MAGIC, /* magic */
1549 "n_tty", /* name */
1550 0, /* num */
1551 0, /* flags */
1552 n_tty_open, /* open */
1553 n_tty_close, /* close */
1554 n_tty_flush_buffer, /* flush_buffer */
1555 n_tty_chars_in_buffer, /* chars_in_buffer */
1556 read_chan, /* read */
1557 write_chan, /* write */
1558 n_tty_ioctl, /* ioctl */
1559 n_tty_set_termios, /* set_termios */
1560 normal_poll, /* poll */
1561 NULL, /* hangup */
1562 n_tty_receive_buf, /* receive_buf */
1563 n_tty_write_wakeup /* write_wakeup */
1564 };