2 * n_tty.c --- implements the N_TTY line discipline.
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,
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.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
21 * Reduced memory usage for older ARM systems - Russell King.
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.
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 n_tty_write returns
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>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/uaccess.h>
51 #include <linux/module.h>
52 #include <linux/ratelimit.h>
55 /* number of characters left in xmit buffer before select has we have room */
56 #define WAKEUP_CHARS 256
59 * This defines the low- and high-watermarks for throttling and
60 * unthrottling the TTY driver. These watermarks are used for
61 * controlling the space in the read buffer.
63 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
64 #define TTY_THRESHOLD_UNTHROTTLE 128
67 * Special byte codes used in the echo buffer to represent operations
68 * or special handling of characters. Bytes in the echo buffer that
69 * are not part of such special blocks are treated as normal character
72 #define ECHO_OP_START 0xff
73 #define ECHO_OP_MOVE_BACK_COL 0x80
74 #define ECHO_OP_SET_CANON_COL 0x81
75 #define ECHO_OP_ERASE_TAB 0x82
79 # define n_tty_trace(f, args...) trace_printk(f, ##args)
81 # define n_tty_trace(f, args...)
85 /* producer-published */
88 DECLARE_BITMAP(process_char_map, 256);
90 /* private to n_tty_receive_overrun (single-threaded) */
91 unsigned long overrun_time;
97 /* must hold exclusive termios_rwsem to reset these */
98 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
100 /* shared by producer and consumer */
102 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
106 /* consumer-published */
109 unsigned char *echo_buf;
114 /* protected by output lock */
116 unsigned int canon_column;
118 struct mutex atomic_read_lock;
119 struct mutex output_lock;
122 static inline size_t read_cnt(struct n_tty_data *ldata)
124 return ldata->read_head - ldata->read_tail;
127 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
129 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
132 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
134 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
137 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
139 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
142 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
144 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
147 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
148 unsigned char __user *ptr)
150 struct n_tty_data *ldata = tty->disc_data;
152 tty_audit_add_data(tty, &x, 1, ldata->icanon);
153 return put_user(x, ptr);
156 static int receive_room(struct tty_struct *tty)
158 struct n_tty_data *ldata = tty->disc_data;
162 /* Multiply read_cnt by 3, since each byte might take up to
163 * three times as many spaces when PARMRK is set (depending on
164 * its flags, e.g. parity error). */
165 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
167 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
170 * If we are doing input canonicalization, and there are no
171 * pending newlines, let characters through without limit, so
172 * that erase characters will be handled. Other excess
173 * characters will be beeped.
176 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
182 * n_tty_set_room - receive space
185 * Re-schedules the flip buffer work if space just became available.
187 * Caller holds exclusive termios_rwsem
189 * n_tty_read()/consumer path:
190 * holds non-exclusive termios_rwsem
193 static void n_tty_set_room(struct tty_struct *tty)
195 struct n_tty_data *ldata = tty->disc_data;
197 /* Did this open up the receive buffer? We may need to flip */
198 if (unlikely(ldata->no_room) && receive_room(tty)) {
201 WARN_RATELIMIT(tty->port->itty == NULL,
202 "scheduling with invalid itty\n");
203 /* see if ldisc has been killed - if so, this means that
204 * even though the ldisc has been halted and ->buf.work
205 * cancelled, ->buf.work is about to be rescheduled
207 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
208 "scheduling buffer work for halted ldisc\n");
209 queue_work(system_unbound_wq, &tty->port->buf.work);
213 static ssize_t chars_in_buffer(struct tty_struct *tty)
215 struct n_tty_data *ldata = tty->disc_data;
221 n = ldata->canon_head - ldata->read_tail;
226 * n_tty_write_wakeup - asynchronous I/O notifier
229 * Required for the ptys, serial driver etc. since processes
230 * that attach themselves to the master and rely on ASYNC
231 * IO must be woken up
234 static void n_tty_write_wakeup(struct tty_struct *tty)
236 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
237 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
240 static inline void n_tty_check_throttle(struct tty_struct *tty)
242 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
245 * Check the remaining room for the input canonicalization
246 * mode. We don't want to throttle the driver if we're in
247 * canonical mode and don't have a newline yet!
251 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
252 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
254 throttled = tty_throttle_safe(tty);
258 __tty_set_flow_change(tty, 0);
261 static inline void n_tty_check_unthrottle(struct tty_struct *tty)
263 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
264 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
265 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
270 n_tty_write_wakeup(tty->link);
271 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
275 /* If there is enough space in the read buffer now, let the
276 * low-level driver know. We use chars_in_buffer() to
277 * check the buffer, as it now knows about canonical mode.
278 * Otherwise, if the driver is throttled and the line is
279 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
280 * we won't get any more characters.
285 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
286 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
291 unthrottled = tty_unthrottle_safe(tty);
295 __tty_set_flow_change(tty, 0);
299 * put_tty_queue - add character to tty
303 * Add a character to the tty read_buf queue.
305 * n_tty_receive_buf()/producer path:
306 * caller holds non-exclusive termios_rwsem
309 * read_head is only considered 'published' if canonical mode is
313 static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
315 if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
316 *read_buf_addr(ldata, ldata->read_head) = c;
322 * reset_buffer_flags - reset buffer state
323 * @tty: terminal to reset
325 * Reset the read buffer counters and clear the flags.
326 * Called from n_tty_open() and n_tty_flush_buffer().
328 * Locking: caller holds exclusive termios_rwsem
329 * (or locking is not required)
332 static void reset_buffer_flags(struct n_tty_data *ldata)
334 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
335 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
338 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
341 static void n_tty_packet_mode_flush(struct tty_struct *tty)
345 spin_lock_irqsave(&tty->ctrl_lock, flags);
346 if (tty->link->packet) {
347 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
348 wake_up_interruptible(&tty->link->read_wait);
350 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
354 * n_tty_flush_buffer - clean input queue
355 * @tty: terminal device
357 * Flush the input buffer. Called when the tty layer wants the
358 * buffer flushed (eg at hangup) or when the N_TTY line discipline
359 * internally has to clean the pending queue (for example some signals).
361 * Holds termios_rwsem to exclude producer/consumer while
362 * buffer indices are reset.
364 * Locking: ctrl_lock, exclusive termios_rwsem
367 static void n_tty_flush_buffer(struct tty_struct *tty)
369 down_write(&tty->termios_rwsem);
370 reset_buffer_flags(tty->disc_data);
374 n_tty_packet_mode_flush(tty);
375 up_write(&tty->termios_rwsem);
379 * n_tty_chars_in_buffer - report available bytes
382 * Report the number of characters buffered to be delivered to user
383 * at this instant in time.
385 * Locking: exclusive termios_rwsem
388 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
392 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
394 down_write(&tty->termios_rwsem);
395 n = chars_in_buffer(tty);
396 up_write(&tty->termios_rwsem);
401 * is_utf8_continuation - utf8 multibyte check
404 * Returns true if the utf8 character 'c' is a multibyte continuation
405 * character. We use this to correctly compute the on screen size
406 * of the character when printing
409 static inline int is_utf8_continuation(unsigned char c)
411 return (c & 0xc0) == 0x80;
415 * is_continuation - multibyte check
418 * Returns true if the utf8 character 'c' is a multibyte continuation
419 * character and the terminal is in unicode mode.
422 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
424 return I_IUTF8(tty) && is_utf8_continuation(c);
428 * do_output_char - output one character
429 * @c: character (or partial unicode symbol)
430 * @tty: terminal device
431 * @space: space available in tty driver write buffer
433 * This is a helper function that handles one output character
434 * (including special characters like TAB, CR, LF, etc.),
435 * doing OPOST processing and putting the results in the
436 * tty driver's write buffer.
438 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
439 * and NLDLY. They simply aren't relevant in the world today.
440 * If you ever need them, add them here.
442 * Returns the number of bytes of buffer space used or -1 if
445 * Locking: should be called under the output_lock to protect
446 * the column state and space left in the buffer
449 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
451 struct n_tty_data *ldata = tty->disc_data;
464 ldata->canon_column = ldata->column = 0;
465 tty->ops->write(tty, "\r\n", 2);
468 ldata->canon_column = ldata->column;
471 if (O_ONOCR(tty) && ldata->column == 0)
476 ldata->canon_column = ldata->column = 0;
479 ldata->canon_column = ldata->column = 0;
482 spaces = 8 - (ldata->column & 7);
483 if (O_TABDLY(tty) == XTABS) {
486 ldata->column += spaces;
487 tty->ops->write(tty, " ", spaces);
490 ldata->column += spaces;
493 if (ldata->column > 0)
500 if (!is_continuation(c, tty))
506 tty_put_char(tty, c);
511 * process_output - output post processor
512 * @c: character (or partial unicode symbol)
513 * @tty: terminal device
515 * Output one character with OPOST processing.
516 * Returns -1 when the output device is full and the character
519 * Locking: output_lock to protect column state and space left
520 * (also, this is called from n_tty_write under the
521 * tty layer write lock)
524 static int process_output(unsigned char c, struct tty_struct *tty)
526 struct n_tty_data *ldata = tty->disc_data;
529 mutex_lock(&ldata->output_lock);
531 space = tty_write_room(tty);
532 retval = do_output_char(c, tty, space);
534 mutex_unlock(&ldata->output_lock);
542 * process_output_block - block post processor
543 * @tty: terminal device
544 * @buf: character buffer
545 * @nr: number of bytes to output
547 * Output a block of characters with OPOST processing.
548 * Returns the number of characters output.
550 * This path is used to speed up block console writes, among other
551 * things when processing blocks of output data. It handles only
552 * the simple cases normally found and helps to generate blocks of
553 * symbols for the console driver and thus improve performance.
555 * Locking: output_lock to protect column state and space left
556 * (also, this is called from n_tty_write under the
557 * tty layer write lock)
560 static ssize_t process_output_block(struct tty_struct *tty,
561 const unsigned char *buf, unsigned int nr)
563 struct n_tty_data *ldata = tty->disc_data;
566 const unsigned char *cp;
568 mutex_lock(&ldata->output_lock);
570 space = tty_write_room(tty);
572 mutex_unlock(&ldata->output_lock);
578 for (i = 0, cp = buf; i < nr; i++, cp++) {
579 unsigned char c = *cp;
587 ldata->canon_column = ldata->column;
590 if (O_ONOCR(tty) && ldata->column == 0)
594 ldata->canon_column = ldata->column = 0;
599 if (ldata->column > 0)
606 if (!is_continuation(c, tty))
613 i = tty->ops->write(tty, buf, i);
615 mutex_unlock(&ldata->output_lock);
620 * process_echoes - write pending echo characters
621 * @tty: terminal device
623 * Write previously buffered echo (and other ldisc-generated)
624 * characters to the tty.
626 * Characters generated by the ldisc (including echoes) need to
627 * be buffered because the driver's write buffer can fill during
628 * heavy program output. Echoing straight to the driver will
629 * often fail under these conditions, causing lost characters and
630 * resulting mismatches of ldisc state information.
632 * Since the ldisc state must represent the characters actually sent
633 * to the driver at the time of the write, operations like certain
634 * changes in column state are also saved in the buffer and executed
637 * A circular fifo buffer is used so that the most recent characters
638 * are prioritized. Also, when control characters are echoed with a
639 * prefixed "^", the pair is treated atomically and thus not separated.
641 * Locking: callers must hold output_lock
644 static void __process_echoes(struct tty_struct *tty)
646 struct n_tty_data *ldata = tty->disc_data;
651 space = tty_write_room(tty);
653 tail = ldata->echo_tail;
654 nr = ldata->echo_commit - ldata->echo_tail;
656 c = echo_buf(ldata, tail);
657 if (c == ECHO_OP_START) {
659 int no_space_left = 0;
662 * If the buffer byte is the start of a multi-byte
663 * operation, get the next byte, which is either the
664 * op code or a control character value.
666 op = echo_buf(ldata, tail + 1);
669 unsigned int num_chars, num_bs;
671 case ECHO_OP_ERASE_TAB:
672 num_chars = echo_buf(ldata, tail + 2);
675 * Determine how many columns to go back
676 * in order to erase the tab.
677 * This depends on the number of columns
678 * used by other characters within the tab
679 * area. If this (modulo 8) count is from
680 * the start of input rather than from a
681 * previous tab, we offset by canon column.
682 * Otherwise, tab spacing is normal.
684 if (!(num_chars & 0x80))
685 num_chars += ldata->canon_column;
686 num_bs = 8 - (num_chars & 7);
688 if (num_bs > space) {
694 tty_put_char(tty, '\b');
695 if (ldata->column > 0)
702 case ECHO_OP_SET_CANON_COL:
703 ldata->canon_column = ldata->column;
708 case ECHO_OP_MOVE_BACK_COL:
709 if (ldata->column > 0)
716 /* This is an escaped echo op start code */
721 tty_put_char(tty, ECHO_OP_START);
730 * If the op is not a special byte code,
731 * it is a ctrl char tagged to be echoed
732 * as "^X" (where X is the letter
733 * representing the control char).
734 * Note that we must ensure there is
735 * enough space for the whole ctrl pair.
742 tty_put_char(tty, '^');
743 tty_put_char(tty, op ^ 0100);
754 int retval = do_output_char(c, tty, space);
761 tty_put_char(tty, c);
769 ldata->echo_tail = tail;
772 static void commit_echoes(struct tty_struct *tty)
774 struct n_tty_data *ldata = tty->disc_data;
776 mutex_lock(&ldata->output_lock);
777 ldata->echo_commit = ldata->echo_head;
778 __process_echoes(tty);
779 mutex_unlock(&ldata->output_lock);
781 if (tty->ops->flush_chars)
782 tty->ops->flush_chars(tty);
785 static void process_echoes(struct tty_struct *tty)
787 struct n_tty_data *ldata = tty->disc_data;
789 if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_tail)
792 mutex_lock(&ldata->output_lock);
793 __process_echoes(tty);
794 mutex_unlock(&ldata->output_lock);
796 if (tty->ops->flush_chars)
797 tty->ops->flush_chars(tty);
801 * add_echo_byte - add a byte to the echo buffer
802 * @c: unicode byte to echo
805 * Add a character or operation byte to the echo buffer.
807 * Locks: may claim output_lock to prevent concurrent modify of
808 * echo_tail by process_echoes().
811 static void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
813 if (ldata->echo_head - ldata->echo_tail == N_TTY_BUF_SIZE) {
814 size_t head = ldata->echo_head;
816 mutex_lock(&ldata->output_lock);
818 * Since the buffer start position needs to be advanced,
819 * be sure to step by a whole operation byte group.
821 if (echo_buf(ldata, head) == ECHO_OP_START) {
822 if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB)
823 ldata->echo_tail += 3;
825 ldata->echo_tail += 2;
828 mutex_unlock(&ldata->output_lock);
831 *echo_buf_addr(ldata, ldata->echo_head++) = c;
835 * echo_move_back_col - add operation to move back a column
838 * Add an operation to the echo buffer to move back one column.
841 static void echo_move_back_col(struct n_tty_data *ldata)
843 add_echo_byte(ECHO_OP_START, ldata);
844 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
848 * echo_set_canon_col - add operation to set the canon column
851 * Add an operation to the echo buffer to set the canon column
852 * to the current column.
855 static void echo_set_canon_col(struct n_tty_data *ldata)
857 add_echo_byte(ECHO_OP_START, ldata);
858 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
862 * echo_erase_tab - add operation to erase a tab
863 * @num_chars: number of character columns already used
864 * @after_tab: true if num_chars starts after a previous tab
867 * Add an operation to the echo buffer to erase a tab.
869 * Called by the eraser function, which knows how many character
870 * columns have been used since either a previous tab or the start
871 * of input. This information will be used later, along with
872 * canon column (if applicable), to go back the correct number
876 static void echo_erase_tab(unsigned int num_chars, int after_tab,
877 struct n_tty_data *ldata)
879 add_echo_byte(ECHO_OP_START, ldata);
880 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
882 /* We only need to know this modulo 8 (tab spacing) */
885 /* Set the high bit as a flag if num_chars is after a previous tab */
889 add_echo_byte(num_chars, ldata);
893 * echo_char_raw - echo a character raw
894 * @c: unicode byte to echo
895 * @tty: terminal device
897 * Echo user input back onto the screen. This must be called only when
898 * L_ECHO(tty) is true. Called from the driver receive_buf path.
900 * This variant does not treat control characters specially.
903 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
905 if (c == ECHO_OP_START) {
906 add_echo_byte(ECHO_OP_START, ldata);
907 add_echo_byte(ECHO_OP_START, ldata);
909 add_echo_byte(c, ldata);
914 * echo_char - echo a character
915 * @c: unicode byte to echo
916 * @tty: terminal device
918 * Echo user input back onto the screen. This must be called only when
919 * L_ECHO(tty) is true. Called from the driver receive_buf path.
921 * This variant tags control characters to be echoed as "^X"
922 * (where X is the letter representing the control char).
925 static void echo_char(unsigned char c, struct tty_struct *tty)
927 struct n_tty_data *ldata = tty->disc_data;
929 if (c == ECHO_OP_START) {
930 add_echo_byte(ECHO_OP_START, ldata);
931 add_echo_byte(ECHO_OP_START, ldata);
933 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
934 add_echo_byte(ECHO_OP_START, ldata);
935 add_echo_byte(c, ldata);
940 * finish_erasing - complete erase
944 static inline void finish_erasing(struct n_tty_data *ldata)
946 if (ldata->erasing) {
947 echo_char_raw('/', ldata);
953 * eraser - handle erase function
954 * @c: character input
955 * @tty: terminal device
957 * Perform erase and necessary output when an erase character is
958 * present in the stream from the driver layer. Handles the complexities
959 * of UTF-8 multibyte symbols.
961 * n_tty_receive_buf()/producer path:
962 * caller holds non-exclusive termios_rwsem
965 * Modifying the read_head is not considered a publish in this context
966 * because canonical mode is active -- only canon_head publishes
969 static void eraser(unsigned char c, struct tty_struct *tty)
971 struct n_tty_data *ldata = tty->disc_data;
972 enum { ERASE, WERASE, KILL } kill_type;
977 if (ldata->read_head == ldata->canon_head) {
978 /* process_output('\a', tty); */ /* what do you think? */
981 if (c == ERASE_CHAR(tty))
983 else if (c == WERASE_CHAR(tty))
987 ldata->read_head = ldata->canon_head;
990 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
991 ldata->read_head = ldata->canon_head;
992 finish_erasing(ldata);
993 echo_char(KILL_CHAR(tty), tty);
994 /* Add a newline if ECHOK is on and ECHOKE is off. */
996 echo_char_raw('\n', ldata);
1003 while (ldata->read_head != ldata->canon_head) {
1004 head = ldata->read_head;
1006 /* erase a single possibly multibyte character */
1009 c = read_buf(ldata, head);
1010 } while (is_continuation(c, tty) && head != ldata->canon_head);
1012 /* do not partially erase */
1013 if (is_continuation(c, tty))
1016 if (kill_type == WERASE) {
1017 /* Equivalent to BSD's ALTWERASE. */
1018 if (isalnum(c) || c == '_')
1020 else if (seen_alnums)
1023 cnt = ldata->read_head - head;
1024 ldata->read_head = head;
1026 if (L_ECHOPRT(tty)) {
1027 if (!ldata->erasing) {
1028 echo_char_raw('\\', ldata);
1031 /* if cnt > 1, output a multi-byte character */
1035 echo_char_raw(read_buf(ldata, head), ldata);
1036 echo_move_back_col(ldata);
1038 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1039 echo_char(ERASE_CHAR(tty), tty);
1040 } else if (c == '\t') {
1041 unsigned int num_chars = 0;
1043 size_t tail = ldata->read_head;
1046 * Count the columns used for characters
1047 * since the start of input or after a
1049 * This info is used to go back the correct
1050 * number of columns.
1052 while (tail != ldata->canon_head) {
1054 c = read_buf(ldata, tail);
1058 } else if (iscntrl(c)) {
1061 } else if (!is_continuation(c, tty)) {
1065 echo_erase_tab(num_chars, after_tab, ldata);
1067 if (iscntrl(c) && L_ECHOCTL(tty)) {
1068 echo_char_raw('\b', ldata);
1069 echo_char_raw(' ', ldata);
1070 echo_char_raw('\b', ldata);
1072 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1073 echo_char_raw('\b', ldata);
1074 echo_char_raw(' ', ldata);
1075 echo_char_raw('\b', ldata);
1079 if (kill_type == ERASE)
1082 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1083 finish_erasing(ldata);
1087 * isig - handle the ISIG optio
1091 * Called when a signal is being sent due to terminal input.
1092 * Called from the driver receive_buf path so serialized.
1094 * Locking: ctrl_lock
1097 static inline void isig(int sig, struct tty_struct *tty)
1099 struct pid *tty_pgrp = tty_get_pgrp(tty);
1101 kill_pgrp(tty_pgrp, sig, 1);
1107 * n_tty_receive_break - handle break
1110 * An RS232 break event has been hit in the incoming bitstream. This
1111 * can cause a variety of events depending upon the termios settings.
1113 * n_tty_receive_buf()/producer path:
1114 * caller holds non-exclusive termios_rwsem
1115 * publishes read_head via put_tty_queue()
1117 * Note: may get exclusive termios_rwsem if flushing input buffer
1120 static inline void n_tty_receive_break(struct tty_struct *tty)
1122 struct n_tty_data *ldata = tty->disc_data;
1126 if (I_BRKINT(tty)) {
1128 if (!L_NOFLSH(tty)) {
1129 /* flushing needs exclusive termios_rwsem */
1130 up_read(&tty->termios_rwsem);
1131 n_tty_flush_buffer(tty);
1132 tty_driver_flush_buffer(tty);
1133 down_read(&tty->termios_rwsem);
1137 if (I_PARMRK(tty)) {
1138 put_tty_queue('\377', ldata);
1139 put_tty_queue('\0', ldata);
1141 put_tty_queue('\0', ldata);
1142 wake_up_interruptible(&tty->read_wait);
1146 * n_tty_receive_overrun - handle overrun reporting
1149 * Data arrived faster than we could process it. While the tty
1150 * driver has flagged this the bits that were missed are gone
1153 * Called from the receive_buf path so single threaded. Does not
1154 * need locking as num_overrun and overrun_time are function
1158 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1160 struct n_tty_data *ldata = tty->disc_data;
1163 ldata->num_overrun++;
1164 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1165 time_after(ldata->overrun_time, jiffies)) {
1166 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1168 ldata->num_overrun);
1169 ldata->overrun_time = jiffies;
1170 ldata->num_overrun = 0;
1175 * n_tty_receive_parity_error - error notifier
1176 * @tty: terminal device
1179 * Process a parity error and queue the right data to indicate
1180 * the error case if necessary.
1182 * n_tty_receive_buf()/producer path:
1183 * caller holds non-exclusive termios_rwsem
1184 * publishes read_head via put_tty_queue()
1186 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1189 struct n_tty_data *ldata = tty->disc_data;
1193 if (I_PARMRK(tty)) {
1194 put_tty_queue('\377', ldata);
1195 put_tty_queue('\0', ldata);
1196 put_tty_queue(c, ldata);
1197 } else if (I_INPCK(tty))
1198 put_tty_queue('\0', ldata);
1200 put_tty_queue(c, ldata);
1201 wake_up_interruptible(&tty->read_wait);
1205 * n_tty_receive_char - perform processing
1206 * @tty: terminal device
1209 * Process an individual character of input received from the driver.
1210 * This is serialized with respect to itself by the rules for the
1213 * n_tty_receive_buf()/producer path:
1214 * caller holds non-exclusive termios_rwsem
1215 * publishes canon_head if canonical mode is active
1216 * otherwise, publishes read_head via put_tty_queue()
1219 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1221 struct n_tty_data *ldata = tty->disc_data;
1225 put_tty_queue(c, ldata);
1231 if (I_IUCLC(tty) && L_IEXTEN(tty))
1234 if (L_EXTPROC(tty)) {
1235 put_tty_queue(c, ldata);
1239 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1240 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1241 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1243 process_echoes(tty);
1248 if (c == START_CHAR(tty)) {
1250 process_echoes(tty);
1251 } else if (c == STOP_CHAR(tty))
1258 * If the previous character was LNEXT, or we know that this
1259 * character is not one of the characters that we'll have to
1260 * handle specially, do shortcut processing to speed things
1263 if (!test_bit(c, ldata->process_char_map) || ldata->lnext) {
1265 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1266 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1267 /* beep if no space */
1269 process_output('\a', tty);
1273 finish_erasing(ldata);
1274 /* Record the column of first canon char. */
1275 if (ldata->canon_head == ldata->read_head)
1276 echo_set_canon_col(ldata);
1281 put_tty_queue(c, ldata);
1282 put_tty_queue(c, ldata);
1287 if (c == START_CHAR(tty)) {
1292 if (c == STOP_CHAR(tty)) {
1301 if (c == INTR_CHAR(tty))
1304 if (c == QUIT_CHAR(tty))
1307 if (c == SUSP_CHAR(tty)) {
1309 if (!L_NOFLSH(tty)) {
1310 /* flushing needs exclusive termios_rwsem */
1311 up_read(&tty->termios_rwsem);
1312 n_tty_flush_buffer(tty);
1313 tty_driver_flush_buffer(tty);
1314 down_read(&tty->termios_rwsem);
1332 } else if (c == '\n' && I_INLCR(tty))
1335 if (ldata->icanon) {
1336 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1337 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1342 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1345 finish_erasing(ldata);
1346 if (L_ECHOCTL(tty)) {
1347 echo_char_raw('^', ldata);
1348 echo_char_raw('\b', ldata);
1354 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1356 size_t tail = ldata->canon_head;
1358 finish_erasing(ldata);
1360 echo_char_raw('\n', ldata);
1361 while (tail != ldata->read_head) {
1362 echo_char(read_buf(ldata, tail), tty);
1369 if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {
1371 process_output('\a', tty);
1374 if (L_ECHO(tty) || L_ECHONL(tty)) {
1375 echo_char_raw('\n', ldata);
1378 goto handle_newline;
1380 if (c == EOF_CHAR(tty)) {
1381 if (read_cnt(ldata) >= N_TTY_BUF_SIZE)
1383 if (ldata->canon_head != ldata->read_head)
1384 set_bit(TTY_PUSH, &tty->flags);
1385 c = __DISABLED_CHAR;
1386 goto handle_newline;
1388 if ((c == EOL_CHAR(tty)) ||
1389 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1390 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1392 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {
1394 process_output('\a', tty);
1398 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1401 /* Record the column of first canon char. */
1402 if (ldata->canon_head == ldata->read_head)
1403 echo_set_canon_col(ldata);
1408 * XXX does PARMRK doubling happen for
1409 * EOL_CHAR and EOL2_CHAR?
1412 put_tty_queue(c, ldata);
1415 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1416 put_tty_queue(c, ldata);
1417 ldata->canon_head = ldata->read_head;
1418 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1419 if (waitqueue_active(&tty->read_wait))
1420 wake_up_interruptible(&tty->read_wait);
1425 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1426 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1427 /* beep if no space */
1429 process_output('\a', tty);
1433 finish_erasing(ldata);
1435 echo_char_raw('\n', ldata);
1437 /* Record the column of first canon char. */
1438 if (ldata->canon_head == ldata->read_head)
1439 echo_set_canon_col(ldata);
1446 put_tty_queue(c, ldata);
1448 put_tty_queue(c, ldata);
1452 * n_tty_receive_buf - data receive
1453 * @tty: terminal device
1456 * @count: characters
1458 * Called by the terminal driver when a block of characters has
1459 * been received. This function must be called from soft contexts
1460 * not from interrupt context. The driver is responsible for making
1461 * calls one at a time and in order (or using flush_to_ldisc)
1463 * n_tty_receive_buf()/producer path:
1464 * claims non-exclusive termios_rwsem
1465 * publishes read_head and canon_head
1468 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1469 char *fp, int count)
1471 struct n_tty_data *ldata = tty->disc_data;
1472 const unsigned char *p;
1473 char *f, flags = TTY_NORMAL;
1476 if (ldata->real_raw) {
1479 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1480 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1481 n = min_t(size_t, count, n);
1482 memcpy(read_buf_addr(ldata, head), cp, n);
1483 ldata->read_head += n;
1487 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1488 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1489 n = min_t(size_t, count, n);
1490 memcpy(read_buf_addr(ldata, head), cp, n);
1491 ldata->read_head += n;
1495 for (i = count, p = cp, f = fp; i; i--, p++) {
1500 n_tty_receive_char(tty, *p);
1503 n_tty_receive_break(tty);
1507 n_tty_receive_parity_error(tty, *p);
1510 n_tty_receive_overrun(tty);
1513 printk(KERN_ERR "%s: unknown flag %d\n",
1514 tty_name(tty, buf), flags);
1518 if (tty->ops->flush_chars)
1519 tty->ops->flush_chars(tty);
1522 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1524 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1525 if (waitqueue_active(&tty->read_wait))
1526 wake_up_interruptible(&tty->read_wait);
1529 n_tty_check_throttle(tty);
1532 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1533 char *fp, int count)
1535 down_read(&tty->termios_rwsem);
1536 __receive_buf(tty, cp, fp, count);
1537 up_read(&tty->termios_rwsem);
1540 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1541 char *fp, int count)
1543 struct n_tty_data *ldata = tty->disc_data;
1546 down_read(&tty->termios_rwsem);
1548 tty->receive_room = room = receive_room(tty);
1551 count = min(count, room);
1553 __receive_buf(tty, cp, fp, count);
1555 up_read(&tty->termios_rwsem);
1560 int is_ignored(int sig)
1562 return (sigismember(¤t->blocked, sig) ||
1563 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1567 * n_tty_set_termios - termios data changed
1569 * @old: previous data
1571 * Called by the tty layer when the user changes termios flags so
1572 * that the line discipline can plan ahead. This function cannot sleep
1573 * and is protected from re-entry by the tty layer. The user is
1574 * guaranteed that this function will not be re-entered or in progress
1575 * when the ldisc is closed.
1577 * Locking: Caller holds tty->termios_rwsem
1580 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1582 struct n_tty_data *ldata = tty->disc_data;
1583 int canon_change = 1;
1586 canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
1588 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1589 ldata->canon_head = ldata->read_tail;
1594 if (canon_change && !L_ICANON(tty) && read_cnt(ldata))
1595 wake_up_interruptible(&tty->read_wait);
1597 ldata->icanon = (L_ICANON(tty) != 0);
1599 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1600 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1601 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1603 bitmap_zero(ldata->process_char_map, 256);
1605 if (I_IGNCR(tty) || I_ICRNL(tty))
1606 set_bit('\r', ldata->process_char_map);
1608 set_bit('\n', ldata->process_char_map);
1610 if (L_ICANON(tty)) {
1611 set_bit(ERASE_CHAR(tty), ldata->process_char_map);
1612 set_bit(KILL_CHAR(tty), ldata->process_char_map);
1613 set_bit(EOF_CHAR(tty), ldata->process_char_map);
1614 set_bit('\n', ldata->process_char_map);
1615 set_bit(EOL_CHAR(tty), ldata->process_char_map);
1616 if (L_IEXTEN(tty)) {
1617 set_bit(WERASE_CHAR(tty),
1618 ldata->process_char_map);
1619 set_bit(LNEXT_CHAR(tty),
1620 ldata->process_char_map);
1621 set_bit(EOL2_CHAR(tty),
1622 ldata->process_char_map);
1624 set_bit(REPRINT_CHAR(tty),
1625 ldata->process_char_map);
1629 set_bit(START_CHAR(tty), ldata->process_char_map);
1630 set_bit(STOP_CHAR(tty), ldata->process_char_map);
1633 set_bit(INTR_CHAR(tty), ldata->process_char_map);
1634 set_bit(QUIT_CHAR(tty), ldata->process_char_map);
1635 set_bit(SUSP_CHAR(tty), ldata->process_char_map);
1637 clear_bit(__DISABLED_CHAR, ldata->process_char_map);
1639 ldata->real_raw = 0;
1642 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1643 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1644 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1645 ldata->real_raw = 1;
1647 ldata->real_raw = 0;
1649 n_tty_set_room(tty);
1651 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1652 * been stopped by STOP_CHAR(tty) before it.
1654 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1658 /* The termios change make the tty ready for I/O */
1659 wake_up_interruptible(&tty->write_wait);
1660 wake_up_interruptible(&tty->read_wait);
1664 * n_tty_close - close the ldisc for this tty
1667 * Called from the terminal layer when this line discipline is
1668 * being shut down, either because of a close or becsuse of a
1669 * discipline change. The function will not be called while other
1670 * ldisc methods are in progress.
1673 static void n_tty_close(struct tty_struct *tty)
1675 struct n_tty_data *ldata = tty->disc_data;
1678 n_tty_packet_mode_flush(tty);
1680 kfree(ldata->read_buf);
1681 kfree(ldata->echo_buf);
1683 tty->disc_data = NULL;
1687 * n_tty_open - open an ldisc
1688 * @tty: terminal to open
1690 * Called when this line discipline is being attached to the
1691 * terminal device. Can sleep. Called serialized so that no
1692 * other events will occur in parallel. No further open will occur
1696 static int n_tty_open(struct tty_struct *tty)
1698 struct n_tty_data *ldata;
1700 ldata = kzalloc(sizeof(*ldata), GFP_KERNEL);
1704 ldata->overrun_time = jiffies;
1705 mutex_init(&ldata->atomic_read_lock);
1706 mutex_init(&ldata->output_lock);
1708 /* These are ugly. Currently a malloc failure here can panic */
1709 ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1710 ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1711 if (!ldata->read_buf || !ldata->echo_buf)
1714 tty->disc_data = ldata;
1715 reset_buffer_flags(tty->disc_data);
1717 ldata->minimum_to_wake = 1;
1719 /* indicate buffer work may resume */
1720 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1721 n_tty_set_termios(tty, NULL);
1722 tty_unthrottle(tty);
1726 kfree(ldata->read_buf);
1727 kfree(ldata->echo_buf);
1733 static inline int input_available_p(struct tty_struct *tty, int amt)
1735 struct n_tty_data *ldata = tty->disc_data;
1737 if (ldata->icanon && !L_EXTPROC(tty)) {
1738 if (ldata->canon_head != ldata->read_tail)
1740 } else if (read_cnt(ldata) >= (amt ? amt : 1))
1747 * copy_from_read_buf - copy read data directly
1748 * @tty: terminal device
1752 * Helper function to speed up n_tty_read. It is only called when
1753 * ICANON is off; it copies characters straight from the tty queue to
1754 * user space directly. It can be profitably called twice; once to
1755 * drain the space from the tail pointer to the (physical) end of the
1756 * buffer, and once to drain the space from the (physical) beginning of
1757 * the buffer to head pointer.
1759 * Called under the ldata->atomic_read_lock sem
1761 * n_tty_read()/consumer path:
1762 * caller holds non-exclusive termios_rwsem
1763 * read_tail published
1766 static int copy_from_read_buf(struct tty_struct *tty,
1767 unsigned char __user **b,
1771 struct n_tty_data *ldata = tty->disc_data;
1775 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1778 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1781 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1783 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1784 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1786 ldata->read_tail += n;
1787 /* Turn single EOF into zero-length read */
1788 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1797 * canon_copy_from_read_buf - copy read data in canonical mode
1798 * @tty: terminal device
1802 * Helper function for n_tty_read. It is only called when ICANON is on;
1803 * it copies one line of input up to and including the line-delimiting
1804 * character into the user-space buffer.
1806 * Called under the atomic_read_lock mutex
1808 * n_tty_read()/consumer path:
1809 * caller holds non-exclusive termios_rwsem
1810 * read_tail published
1813 static int canon_copy_from_read_buf(struct tty_struct *tty,
1814 unsigned char __user **b,
1817 struct n_tty_data *ldata = tty->disc_data;
1818 size_t n, size, more, c;
1823 /* N.B. avoid overrun if nr == 0 */
1824 n = min(*nr, read_cnt(ldata));
1828 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1829 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1831 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1832 __func__, *nr, tail, n, size);
1834 eol = find_next_bit(ldata->read_flags, size, tail);
1835 more = n - (size - tail);
1836 if (eol == N_TTY_BUF_SIZE && more) {
1837 /* scan wrapped without finding set bit */
1838 eol = find_next_bit(ldata->read_flags, more, 0);
1841 } else if (eol != size)
1844 size = N_TTY_BUF_SIZE - tail;
1845 n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
1848 if (found && read_buf(ldata, eol) == __DISABLED_CHAR)
1851 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
1852 __func__, eol, found, n, c, size, more);
1855 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
1858 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
1860 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1868 clear_bit(eol, ldata->read_flags);
1869 smp_mb__after_clear_bit();
1870 ldata->read_tail += c;
1873 tty_audit_push(tty);
1877 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1881 * job_control - check job control
1883 * @file: file handle
1885 * Perform job control management checks on this file/tty descriptor
1886 * and if appropriate send any needed signals and return a negative
1887 * error code if action should be taken.
1889 * Locking: redirected write test is safe
1890 * current->signal->tty check is safe
1891 * ctrl_lock to safely reference tty->pgrp
1894 static int job_control(struct tty_struct *tty, struct file *file)
1896 /* Job control check -- must be done at start and after
1897 every sleep (POSIX.1 7.1.1.4). */
1898 /* NOTE: not yet done after every sleep pending a thorough
1899 check of the logic of this change. -- jlc */
1900 /* don't stop on /dev/console */
1901 if (file->f_op->write == redirected_tty_write ||
1902 current->signal->tty != tty)
1905 spin_lock_irq(&tty->ctrl_lock);
1907 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1908 else if (task_pgrp(current) != tty->pgrp) {
1909 spin_unlock_irq(&tty->ctrl_lock);
1910 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
1912 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1913 set_thread_flag(TIF_SIGPENDING);
1914 return -ERESTARTSYS;
1916 spin_unlock_irq(&tty->ctrl_lock);
1922 * n_tty_read - read function for tty
1924 * @file: file object
1925 * @buf: userspace buffer pointer
1928 * Perform reads for the line discipline. We are guaranteed that the
1929 * line discipline will not be closed under us but we may get multiple
1930 * parallel readers and must handle this ourselves. We may also get
1931 * a hangup. Always called in user context, may sleep.
1933 * This code must be sure never to sleep through a hangup.
1935 * n_tty_read()/consumer path:
1936 * claims non-exclusive termios_rwsem
1937 * publishes read_tail
1940 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1941 unsigned char __user *buf, size_t nr)
1943 struct n_tty_data *ldata = tty->disc_data;
1944 unsigned char __user *b = buf;
1945 DECLARE_WAITQUEUE(wait, current);
1951 unsigned long flags;
1955 c = job_control(tty, file);
1959 down_read(&tty->termios_rwsem);
1962 timeout = MAX_SCHEDULE_TIMEOUT;
1963 if (!ldata->icanon) {
1964 minimum = MIN_CHAR(tty);
1966 time = (HZ / 10) * TIME_CHAR(tty);
1968 ldata->minimum_to_wake = 1;
1969 else if (!waitqueue_active(&tty->read_wait) ||
1970 (ldata->minimum_to_wake > minimum))
1971 ldata->minimum_to_wake = minimum;
1973 timeout = (HZ / 10) * TIME_CHAR(tty);
1974 ldata->minimum_to_wake = minimum = 1;
1979 * Internal serialization of reads.
1981 if (file->f_flags & O_NONBLOCK) {
1982 if (!mutex_trylock(&ldata->atomic_read_lock)) {
1983 up_read(&tty->termios_rwsem);
1987 if (mutex_lock_interruptible(&ldata->atomic_read_lock)) {
1988 up_read(&tty->termios_rwsem);
1989 return -ERESTARTSYS;
1992 packet = tty->packet;
1994 add_wait_queue(&tty->read_wait, &wait);
1996 /* First test for status change. */
1997 if (packet && tty->link->ctrl_status) {
2001 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2002 cs = tty->link->ctrl_status;
2003 tty->link->ctrl_status = 0;
2004 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2005 if (tty_put_user(tty, cs, b++)) {
2013 /* This statement must be first before checking for input
2014 so that any interrupt will set the state back to
2016 set_current_state(TASK_INTERRUPTIBLE);
2018 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2019 ((minimum - (b - buf)) >= 1))
2020 ldata->minimum_to_wake = (minimum - (b - buf));
2022 if (!input_available_p(tty, 0)) {
2023 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2027 if (tty_hung_up_p(file))
2031 if (file->f_flags & O_NONBLOCK) {
2035 if (signal_pending(current)) {
2036 retval = -ERESTARTSYS;
2039 n_tty_set_room(tty);
2040 up_read(&tty->termios_rwsem);
2042 timeout = schedule_timeout(timeout);
2044 down_read(&tty->termios_rwsem);
2047 __set_current_state(TASK_RUNNING);
2049 /* Deal with packet mode. */
2050 if (packet && b == buf) {
2051 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2059 if (ldata->icanon && !L_EXTPROC(tty)) {
2060 retval = canon_copy_from_read_buf(tty, &b, &nr);
2065 /* The copy function takes the read lock and handles
2066 locking internally for this case */
2067 uncopied = copy_from_read_buf(tty, &b, &nr);
2068 uncopied += copy_from_read_buf(tty, &b, &nr);
2075 n_tty_check_unthrottle(tty);
2077 if (b - buf >= minimum)
2082 mutex_unlock(&ldata->atomic_read_lock);
2083 remove_wait_queue(&tty->read_wait, &wait);
2085 if (!waitqueue_active(&tty->read_wait))
2086 ldata->minimum_to_wake = minimum;
2088 __set_current_state(TASK_RUNNING);
2093 clear_bit(TTY_PUSH, &tty->flags);
2094 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) {
2095 up_read(&tty->termios_rwsem);
2099 n_tty_set_room(tty);
2100 up_read(&tty->termios_rwsem);
2105 * n_tty_write - write function for tty
2107 * @file: file object
2108 * @buf: userspace buffer pointer
2111 * Write function of the terminal device. This is serialized with
2112 * respect to other write callers but not to termios changes, reads
2113 * and other such events. Since the receive code will echo characters,
2114 * thus calling driver write methods, the output_lock is used in
2115 * the output processing functions called here as well as in the
2116 * echo processing function to protect the column state and space
2117 * left in the buffer.
2119 * This code must be sure never to sleep through a hangup.
2121 * Locking: output_lock to protect column state and space left
2122 * (note that the process_output*() functions take this
2126 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2127 const unsigned char *buf, size_t nr)
2129 const unsigned char *b = buf;
2130 DECLARE_WAITQUEUE(wait, current);
2134 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2135 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2136 retval = tty_check_change(tty);
2141 down_read(&tty->termios_rwsem);
2143 /* Write out any echoed characters that are still pending */
2144 process_echoes(tty);
2146 add_wait_queue(&tty->write_wait, &wait);
2148 set_current_state(TASK_INTERRUPTIBLE);
2149 if (signal_pending(current)) {
2150 retval = -ERESTARTSYS;
2153 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2159 ssize_t num = process_output_block(tty, b, nr);
2171 if (process_output(c, tty) < 0)
2175 if (tty->ops->flush_chars)
2176 tty->ops->flush_chars(tty);
2179 c = tty->ops->write(tty, b, nr);
2192 if (file->f_flags & O_NONBLOCK) {
2196 up_read(&tty->termios_rwsem);
2200 down_read(&tty->termios_rwsem);
2203 __set_current_state(TASK_RUNNING);
2204 remove_wait_queue(&tty->write_wait, &wait);
2205 if (b - buf != nr && tty->fasync)
2206 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2207 up_read(&tty->termios_rwsem);
2208 return (b - buf) ? b - buf : retval;
2212 * n_tty_poll - poll method for N_TTY
2213 * @tty: terminal device
2214 * @file: file accessing it
2217 * Called when the line discipline is asked to poll() for data or
2218 * for special events. This code is not serialized with respect to
2219 * other events save open/close.
2221 * This code must be sure never to sleep through a hangup.
2222 * Called without the kernel lock held - fine
2225 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2228 struct n_tty_data *ldata = tty->disc_data;
2229 unsigned int mask = 0;
2231 poll_wait(file, &tty->read_wait, wait);
2232 poll_wait(file, &tty->write_wait, wait);
2233 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2234 mask |= POLLIN | POLLRDNORM;
2235 if (tty->packet && tty->link->ctrl_status)
2236 mask |= POLLPRI | POLLIN | POLLRDNORM;
2237 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2239 if (tty_hung_up_p(file))
2241 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2242 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2243 ldata->minimum_to_wake = MIN_CHAR(tty);
2245 ldata->minimum_to_wake = 1;
2247 if (tty->ops->write && !tty_is_writelocked(tty) &&
2248 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2249 tty_write_room(tty) > 0)
2250 mask |= POLLOUT | POLLWRNORM;
2254 static unsigned long inq_canon(struct n_tty_data *ldata)
2256 size_t nr, head, tail;
2258 if (ldata->canon_head == ldata->read_tail)
2260 head = ldata->canon_head;
2261 tail = ldata->read_tail;
2263 /* Skip EOF-chars.. */
2264 while (head != tail) {
2265 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2266 read_buf(ldata, tail) == __DISABLED_CHAR)
2273 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2274 unsigned int cmd, unsigned long arg)
2276 struct n_tty_data *ldata = tty->disc_data;
2281 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2283 down_write(&tty->termios_rwsem);
2285 retval = inq_canon(ldata);
2287 retval = read_cnt(ldata);
2288 up_write(&tty->termios_rwsem);
2289 return put_user(retval, (unsigned int __user *) arg);
2291 return n_tty_ioctl_helper(tty, file, cmd, arg);
2295 static void n_tty_fasync(struct tty_struct *tty, int on)
2297 struct n_tty_data *ldata = tty->disc_data;
2299 if (!waitqueue_active(&tty->read_wait)) {
2301 ldata->minimum_to_wake = 1;
2302 else if (!tty->fasync)
2303 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2307 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2308 .magic = TTY_LDISC_MAGIC,
2311 .close = n_tty_close,
2312 .flush_buffer = n_tty_flush_buffer,
2313 .chars_in_buffer = n_tty_chars_in_buffer,
2315 .write = n_tty_write,
2316 .ioctl = n_tty_ioctl,
2317 .set_termios = n_tty_set_termios,
2319 .receive_buf = n_tty_receive_buf,
2320 .write_wakeup = n_tty_write_wakeup,
2321 .fasync = n_tty_fasync,
2322 .receive_buf2 = n_tty_receive_buf2,
2326 * n_tty_inherit_ops - inherit N_TTY methods
2327 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2329 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2333 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2335 *ops = tty_ldisc_N_TTY;
2337 ops->refcount = ops->flags = 0;
2339 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);