diff options
author | Alan Cox <alan@redhat.com> | 2008-10-13 05:45:06 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-13 12:51:44 -0400 |
commit | 17b820606e7bdd3be31b001265d0177423fea5eb (patch) | |
tree | df962dfca41e133983ee1a68deaad646a311d8b2 /drivers | |
parent | 51383f69ec56fe3f425d5255fb43e18c445e061c (diff) |
tty: Minor tidyups and document fixes for n_tty
Remove/fix some bogus NULL checks, comment some locking etc
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/char/n_tty.c | 48 |
1 files changed, 37 insertions, 11 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c index b4f5dccad2a6..c0285b95cf94 100644 --- a/drivers/char/n_tty.c +++ b/drivers/char/n_tty.c | |||
@@ -99,6 +99,7 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, | |||
99 | 99 | ||
100 | static void n_tty_set_room(struct tty_struct *tty) | 100 | static void n_tty_set_room(struct tty_struct *tty) |
101 | { | 101 | { |
102 | /* tty->read_cnt is not read locked ? */ | ||
102 | int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; | 103 | int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; |
103 | 104 | ||
104 | /* | 105 | /* |
@@ -121,6 +122,16 @@ static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) | |||
121 | } | 122 | } |
122 | } | 123 | } |
123 | 124 | ||
125 | /** | ||
126 | * put_tty_queue - add character to tty | ||
127 | * @c: character | ||
128 | * @tty: tty device | ||
129 | * | ||
130 | * Add a character to the tty read_buf queue. This is done under the | ||
131 | * read_lock to serialize character addition and also to protect us | ||
132 | * against parallel reads or flushes | ||
133 | */ | ||
134 | |||
124 | static void put_tty_queue(unsigned char c, struct tty_struct *tty) | 135 | static void put_tty_queue(unsigned char c, struct tty_struct *tty) |
125 | { | 136 | { |
126 | unsigned long flags; | 137 | unsigned long flags; |
@@ -137,14 +148,11 @@ static void put_tty_queue(unsigned char c, struct tty_struct *tty) | |||
137 | * check_unthrottle - allow new receive data | 148 | * check_unthrottle - allow new receive data |
138 | * @tty; tty device | 149 | * @tty; tty device |
139 | * | 150 | * |
140 | * Check whether to call the driver.unthrottle function. | 151 | * Check whether to call the driver unthrottle functions |
141 | * We test the TTY_THROTTLED bit first so that it always | 152 | * |
142 | * indicates the current state. The decision about whether | ||
143 | * it is worth allowing more input has been taken by the caller. | ||
144 | * Can sleep, may be called under the atomic_read_lock mutex but | 153 | * Can sleep, may be called under the atomic_read_lock mutex but |
145 | * this is not guaranteed. | 154 | * this is not guaranteed. |
146 | */ | 155 | */ |
147 | |||
148 | static void check_unthrottle(struct tty_struct *tty) | 156 | static void check_unthrottle(struct tty_struct *tty) |
149 | { | 157 | { |
150 | if (tty->count) | 158 | if (tty->count) |
@@ -158,6 +166,8 @@ static void check_unthrottle(struct tty_struct *tty) | |||
158 | * Reset the read buffer counters, clear the flags, | 166 | * Reset the read buffer counters, clear the flags, |
159 | * and make sure the driver is unthrottled. Called | 167 | * and make sure the driver is unthrottled. Called |
160 | * from n_tty_open() and n_tty_flush_buffer(). | 168 | * from n_tty_open() and n_tty_flush_buffer(). |
169 | * | ||
170 | * Locking: tty_read_lock for read fields. | ||
161 | */ | 171 | */ |
162 | static void reset_buffer_flags(struct tty_struct *tty) | 172 | static void reset_buffer_flags(struct tty_struct *tty) |
163 | { | 173 | { |
@@ -181,7 +191,7 @@ static void reset_buffer_flags(struct tty_struct *tty) | |||
181 | * at hangup) or when the N_TTY line discipline internally has to | 191 | * at hangup) or when the N_TTY line discipline internally has to |
182 | * clean the pending queue (for example some signals). | 192 | * clean the pending queue (for example some signals). |
183 | * | 193 | * |
184 | * Locking: ctrl_lock | 194 | * Locking: ctrl_lock, read_lock. |
185 | */ | 195 | */ |
186 | 196 | ||
187 | static void n_tty_flush_buffer(struct tty_struct *tty) | 197 | static void n_tty_flush_buffer(struct tty_struct *tty) |
@@ -207,6 +217,8 @@ static void n_tty_flush_buffer(struct tty_struct *tty) | |||
207 | * | 217 | * |
208 | * Report the number of characters buffered to be delivered to user | 218 | * Report the number of characters buffered to be delivered to user |
209 | * at this instant in time. | 219 | * at this instant in time. |
220 | * | ||
221 | * Locking: read_lock | ||
210 | */ | 222 | */ |
211 | 223 | ||
212 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) | 224 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) |
@@ -410,6 +422,8 @@ break_out: | |||
410 | * | 422 | * |
411 | * Echo user input back onto the screen. This must be called only when | 423 | * Echo user input back onto the screen. This must be called only when |
412 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | 424 | * L_ECHO(tty) is true. Called from the driver receive_buf path. |
425 | * | ||
426 | * Relies on BKL for tty column locking | ||
413 | */ | 427 | */ |
414 | 428 | ||
415 | static void echo_char(unsigned char c, struct tty_struct *tty) | 429 | static void echo_char(unsigned char c, struct tty_struct *tty) |
@@ -422,6 +436,12 @@ static void echo_char(unsigned char c, struct tty_struct *tty) | |||
422 | opost(c, tty); | 436 | opost(c, tty); |
423 | } | 437 | } |
424 | 438 | ||
439 | /** | ||
440 | * finsh_erasing - complete erase | ||
441 | * @tty: tty doing the erase | ||
442 | * | ||
443 | * Relies on BKL for tty column locking | ||
444 | */ | ||
425 | static inline void finish_erasing(struct tty_struct *tty) | 445 | static inline void finish_erasing(struct tty_struct *tty) |
426 | { | 446 | { |
427 | if (tty->erasing) { | 447 | if (tty->erasing) { |
@@ -439,6 +459,8 @@ static inline void finish_erasing(struct tty_struct *tty) | |||
439 | * Perform erase and necessary output when an erase character is | 459 | * Perform erase and necessary output when an erase character is |
440 | * present in the stream from the driver layer. Handles the complexities | 460 | * present in the stream from the driver layer. Handles the complexities |
441 | * of UTF-8 multibyte symbols. | 461 | * of UTF-8 multibyte symbols. |
462 | * | ||
463 | * Locking: read_lock for tty buffers, BKL for column/erasing state | ||
442 | */ | 464 | */ |
443 | 465 | ||
444 | static void eraser(unsigned char c, struct tty_struct *tty) | 466 | static void eraser(unsigned char c, struct tty_struct *tty) |
@@ -447,6 +469,7 @@ static void eraser(unsigned char c, struct tty_struct *tty) | |||
447 | int head, seen_alnums, cnt; | 469 | int head, seen_alnums, cnt; |
448 | unsigned long flags; | 470 | unsigned long flags; |
449 | 471 | ||
472 | /* FIXME: locking needed ? */ | ||
450 | if (tty->read_head == tty->canon_head) { | 473 | if (tty->read_head == tty->canon_head) { |
451 | /* opost('\a', tty); */ /* what do you think? */ | 474 | /* opost('\a', tty); */ /* what do you think? */ |
452 | return; | 475 | return; |
@@ -481,6 +504,7 @@ static void eraser(unsigned char c, struct tty_struct *tty) | |||
481 | } | 504 | } |
482 | 505 | ||
483 | seen_alnums = 0; | 506 | seen_alnums = 0; |
507 | /* FIXME: Locking ?? */ | ||
484 | while (tty->read_head != tty->canon_head) { | 508 | while (tty->read_head != tty->canon_head) { |
485 | head = tty->read_head; | 509 | head = tty->read_head; |
486 | 510 | ||
@@ -583,6 +607,8 @@ static void eraser(unsigned char c, struct tty_struct *tty) | |||
583 | * may caus terminal flushing to take place according to the termios | 607 | * may caus terminal flushing to take place according to the termios |
584 | * settings and character used. Called from the driver receive_buf | 608 | * settings and character used. Called from the driver receive_buf |
585 | * path so serialized. | 609 | * path so serialized. |
610 | * | ||
611 | * Locking: ctrl_lock, read_lock (both via flush buffer) | ||
586 | */ | 612 | */ |
587 | 613 | ||
588 | static inline void isig(int sig, struct tty_struct *tty, int flush) | 614 | static inline void isig(int sig, struct tty_struct *tty, int flush) |
@@ -1007,6 +1033,8 @@ int is_ignored(int sig) | |||
1007 | * and is protected from re-entry by the tty layer. The user is | 1033 | * and is protected from re-entry by the tty layer. The user is |
1008 | * guaranteed that this function will not be re-entered or in progress | 1034 | * guaranteed that this function will not be re-entered or in progress |
1009 | * when the ldisc is closed. | 1035 | * when the ldisc is closed. |
1036 | * | ||
1037 | * Locking: Caller holds tty->termios_mutex | ||
1010 | */ | 1038 | */ |
1011 | 1039 | ||
1012 | static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) | 1040 | static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) |
@@ -1266,10 +1294,7 @@ static ssize_t read_chan(struct tty_struct *tty, struct file *file, | |||
1266 | 1294 | ||
1267 | do_it_again: | 1295 | do_it_again: |
1268 | 1296 | ||
1269 | if (!tty->read_buf) { | 1297 | BUG_ON(!tty->read_buf); |
1270 | printk(KERN_ERR "n_tty_read_chan: read_buf == NULL?!?\n"); | ||
1271 | return -EIO; | ||
1272 | } | ||
1273 | 1298 | ||
1274 | c = job_control(tty, file); | 1299 | c = job_control(tty, file); |
1275 | if (c < 0) | 1300 | if (c < 0) |
@@ -1589,7 +1614,7 @@ static unsigned long inq_canon(struct tty_struct *tty) | |||
1589 | { | 1614 | { |
1590 | int nr, head, tail; | 1615 | int nr, head, tail; |
1591 | 1616 | ||
1592 | if (!tty->canon_data || !tty->read_buf) | 1617 | if (!tty->canon_data) |
1593 | return 0; | 1618 | return 0; |
1594 | head = tty->canon_head; | 1619 | head = tty->canon_head; |
1595 | tail = tty->read_tail; | 1620 | tail = tty->read_tail; |
@@ -1613,6 +1638,7 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file, | |||
1613 | case TIOCOUTQ: | 1638 | case TIOCOUTQ: |
1614 | return put_user(tty_chars_in_buffer(tty), (int __user *) arg); | 1639 | return put_user(tty_chars_in_buffer(tty), (int __user *) arg); |
1615 | case TIOCINQ: | 1640 | case TIOCINQ: |
1641 | /* FIXME: Locking */ | ||
1616 | retval = tty->read_cnt; | 1642 | retval = tty->read_cnt; |
1617 | if (L_ICANON(tty)) | 1643 | if (L_ICANON(tty)) |
1618 | retval = inq_canon(tty); | 1644 | retval = inq_canon(tty); |