]>
Commit | Line | Data |
---|---|---|
01e1abb2 | 1 | #include <linux/types.h> |
01e1abb2 | 2 | #include <linux/errno.h> |
8b3ffa17 | 3 | #include <linux/kmod.h> |
01e1abb2 AC |
4 | #include <linux/sched.h> |
5 | #include <linux/interrupt.h> | |
6 | #include <linux/tty.h> | |
7 | #include <linux/tty_driver.h> | |
01e1abb2 | 8 | #include <linux/file.h> |
01e1abb2 AC |
9 | #include <linux/mm.h> |
10 | #include <linux/string.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/poll.h> | |
13 | #include <linux/proc_fs.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/module.h> | |
01e1abb2 AC |
16 | #include <linux/device.h> |
17 | #include <linux/wait.h> | |
18 | #include <linux/bitops.h> | |
01e1abb2 | 19 | #include <linux/seq_file.h> |
01e1abb2 | 20 | #include <linux/uaccess.h> |
0c73c08e | 21 | #include <linux/ratelimit.h> |
01e1abb2 | 22 | |
fc575ee6 PH |
23 | #undef LDISC_DEBUG_HANGUP |
24 | ||
25 | #ifdef LDISC_DEBUG_HANGUP | |
26 | #define tty_ldisc_debug(tty, f, args...) ({ \ | |
27 | char __b[64]; \ | |
28 | printk(KERN_DEBUG "%s: %s: " f, __func__, tty_name(tty, __b), ##args); \ | |
29 | }) | |
30 | #else | |
31 | #define tty_ldisc_debug(tty, f, args...) | |
32 | #endif | |
33 | ||
d2c43890 PH |
34 | /* lockdep nested classes for tty->ldisc_sem */ |
35 | enum { | |
36 | LDISC_SEM_NORMAL, | |
37 | LDISC_SEM_OTHER, | |
38 | }; | |
39 | ||
40 | ||
01e1abb2 AC |
41 | /* |
42 | * This guards the refcounted line discipline lists. The lock | |
43 | * must be taken with irqs off because there are hangup path | |
44 | * callers who will do ldisc lookups and cannot sleep. | |
45 | */ | |
46 | ||
137084bb | 47 | static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); |
01e1abb2 AC |
48 | static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); |
49 | /* Line disc dispatch table */ | |
50 | static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; | |
51 | ||
52 | /** | |
53 | * tty_register_ldisc - install a line discipline | |
54 | * @disc: ldisc number | |
55 | * @new_ldisc: pointer to the ldisc object | |
56 | * | |
57 | * Installs a new line discipline into the kernel. The discipline | |
58 | * is set up as unreferenced and then made available to the kernel | |
59 | * from this point onwards. | |
60 | * | |
61 | * Locking: | |
137084bb | 62 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
63 | */ |
64 | ||
65 | int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) | |
66 | { | |
67 | unsigned long flags; | |
68 | int ret = 0; | |
69 | ||
70 | if (disc < N_TTY || disc >= NR_LDISCS) | |
71 | return -EINVAL; | |
72 | ||
137084bb | 73 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
74 | tty_ldiscs[disc] = new_ldisc; |
75 | new_ldisc->num = disc; | |
76 | new_ldisc->refcount = 0; | |
137084bb | 77 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
78 | |
79 | return ret; | |
80 | } | |
81 | EXPORT_SYMBOL(tty_register_ldisc); | |
82 | ||
83 | /** | |
84 | * tty_unregister_ldisc - unload a line discipline | |
85 | * @disc: ldisc number | |
86 | * @new_ldisc: pointer to the ldisc object | |
87 | * | |
88 | * Remove a line discipline from the kernel providing it is not | |
89 | * currently in use. | |
90 | * | |
91 | * Locking: | |
137084bb | 92 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
93 | */ |
94 | ||
95 | int tty_unregister_ldisc(int disc) | |
96 | { | |
97 | unsigned long flags; | |
98 | int ret = 0; | |
99 | ||
100 | if (disc < N_TTY || disc >= NR_LDISCS) | |
101 | return -EINVAL; | |
102 | ||
137084bb | 103 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
104 | if (tty_ldiscs[disc]->refcount) |
105 | ret = -EBUSY; | |
106 | else | |
107 | tty_ldiscs[disc] = NULL; | |
137084bb | 108 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
109 | |
110 | return ret; | |
111 | } | |
112 | EXPORT_SYMBOL(tty_unregister_ldisc); | |
113 | ||
f0de0e8d LT |
114 | static struct tty_ldisc_ops *get_ldops(int disc) |
115 | { | |
116 | unsigned long flags; | |
117 | struct tty_ldisc_ops *ldops, *ret; | |
118 | ||
137084bb | 119 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
120 | ret = ERR_PTR(-EINVAL); |
121 | ldops = tty_ldiscs[disc]; | |
122 | if (ldops) { | |
123 | ret = ERR_PTR(-EAGAIN); | |
124 | if (try_module_get(ldops->owner)) { | |
125 | ldops->refcount++; | |
126 | ret = ldops; | |
127 | } | |
128 | } | |
137084bb | 129 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
130 | return ret; |
131 | } | |
132 | ||
133 | static void put_ldops(struct tty_ldisc_ops *ldops) | |
134 | { | |
135 | unsigned long flags; | |
136 | ||
137084bb | 137 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
138 | ldops->refcount--; |
139 | module_put(ldops->owner); | |
137084bb | 140 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
f0de0e8d | 141 | } |
01e1abb2 | 142 | |
01e1abb2 AC |
143 | /** |
144 | * tty_ldisc_get - take a reference to an ldisc | |
145 | * @disc: ldisc number | |
01e1abb2 AC |
146 | * |
147 | * Takes a reference to a line discipline. Deals with refcounts and | |
148 | * module locking counts. Returns NULL if the discipline is not available. | |
149 | * Returns a pointer to the discipline and bumps the ref count if it is | |
150 | * available | |
151 | * | |
152 | * Locking: | |
137084bb | 153 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
154 | */ |
155 | ||
c65c9bc3 | 156 | static struct tty_ldisc *tty_ldisc_get(int disc) |
01e1abb2 | 157 | { |
c65c9bc3 | 158 | struct tty_ldisc *ld; |
182274f8 | 159 | struct tty_ldisc_ops *ldops; |
01e1abb2 AC |
160 | |
161 | if (disc < N_TTY || disc >= NR_LDISCS) | |
c65c9bc3 | 162 | return ERR_PTR(-EINVAL); |
182274f8 LT |
163 | |
164 | /* | |
165 | * Get the ldisc ops - we may need to request them to be loaded | |
166 | * dynamically and try again. | |
167 | */ | |
168 | ldops = get_ldops(disc); | |
169 | if (IS_ERR(ldops)) { | |
01e1abb2 | 170 | request_module("tty-ldisc-%d", disc); |
182274f8 LT |
171 | ldops = get_ldops(disc); |
172 | if (IS_ERR(ldops)) | |
173 | return ERR_CAST(ldops); | |
174 | } | |
175 | ||
176 | ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); | |
177 | if (ld == NULL) { | |
178 | put_ldops(ldops); | |
179 | return ERR_PTR(-ENOMEM); | |
01e1abb2 | 180 | } |
182274f8 LT |
181 | |
182 | ld->ops = ldops; | |
183 | atomic_set(&ld->users, 1); | |
1541f845 IS |
184 | init_waitqueue_head(&ld->wq_idle); |
185 | ||
c65c9bc3 | 186 | return ld; |
01e1abb2 AC |
187 | } |
188 | ||
734de249 PH |
189 | /** |
190 | * tty_ldisc_put - release the ldisc | |
191 | * | |
192 | * Complement of tty_ldisc_get(). | |
193 | */ | |
194 | static inline void tty_ldisc_put(struct tty_ldisc *ld) | |
195 | { | |
196 | unsigned long flags; | |
197 | ||
198 | if (WARN_ON_ONCE(!ld)) | |
199 | return; | |
200 | ||
137084bb | 201 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
734de249 PH |
202 | |
203 | /* unreleased reader reference(s) will cause this WARN */ | |
204 | WARN_ON(!atomic_dec_and_test(&ld->users)); | |
205 | ||
206 | ld->ops->refcount--; | |
207 | module_put(ld->ops->owner); | |
208 | kfree(ld); | |
137084bb | 209 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
734de249 PH |
210 | } |
211 | ||
852e99d2 | 212 | static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) |
01e1abb2 AC |
213 | { |
214 | return (*pos < NR_LDISCS) ? pos : NULL; | |
215 | } | |
216 | ||
852e99d2 | 217 | static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) |
01e1abb2 AC |
218 | { |
219 | (*pos)++; | |
220 | return (*pos < NR_LDISCS) ? pos : NULL; | |
221 | } | |
222 | ||
223 | static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) | |
224 | { | |
225 | } | |
226 | ||
227 | static int tty_ldiscs_seq_show(struct seq_file *m, void *v) | |
228 | { | |
229 | int i = *(loff_t *)v; | |
f0de0e8d | 230 | struct tty_ldisc_ops *ldops; |
852e99d2 | 231 | |
f0de0e8d LT |
232 | ldops = get_ldops(i); |
233 | if (IS_ERR(ldops)) | |
01e1abb2 | 234 | return 0; |
f0de0e8d LT |
235 | seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); |
236 | put_ldops(ldops); | |
01e1abb2 AC |
237 | return 0; |
238 | } | |
239 | ||
240 | static const struct seq_operations tty_ldiscs_seq_ops = { | |
241 | .start = tty_ldiscs_seq_start, | |
242 | .next = tty_ldiscs_seq_next, | |
243 | .stop = tty_ldiscs_seq_stop, | |
244 | .show = tty_ldiscs_seq_show, | |
245 | }; | |
246 | ||
247 | static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) | |
248 | { | |
249 | return seq_open(file, &tty_ldiscs_seq_ops); | |
250 | } | |
251 | ||
252 | const struct file_operations tty_ldiscs_proc_fops = { | |
253 | .owner = THIS_MODULE, | |
254 | .open = proc_tty_ldiscs_open, | |
255 | .read = seq_read, | |
256 | .llseek = seq_lseek, | |
257 | .release = seq_release, | |
258 | }; | |
259 | ||
01e1abb2 AC |
260 | /** |
261 | * tty_ldisc_try - internal helper | |
262 | * @tty: the tty | |
263 | * | |
264 | * Make a single attempt to grab and bump the refcount on | |
265 | * the tty ldisc. Return 0 on failure or 1 on success. This is | |
266 | * used to implement both the waiting and non waiting versions | |
267 | * of tty_ldisc_ref | |
268 | * | |
137084bb | 269 | * Locking: takes tty_ldiscs_lock |
01e1abb2 AC |
270 | */ |
271 | ||
65b77046 | 272 | static struct tty_ldisc *tty_ldisc_try(struct tty_struct *tty) |
01e1abb2 AC |
273 | { |
274 | unsigned long flags; | |
275 | struct tty_ldisc *ld; | |
01e1abb2 | 276 | |
16759f6c | 277 | /* FIXME: this allows reference acquire after TTY_LDISC is cleared */ |
137084bb | 278 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
65b77046 | 279 | ld = NULL; |
16759f6c PH |
280 | if (test_bit(TTY_LDISC, &tty->flags) && tty->ldisc) { |
281 | ld = tty->ldisc; | |
282 | atomic_inc(&ld->users); | |
283 | } | |
137084bb | 284 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
65b77046 | 285 | return ld; |
01e1abb2 AC |
286 | } |
287 | ||
288 | /** | |
289 | * tty_ldisc_ref_wait - wait for the tty ldisc | |
290 | * @tty: tty device | |
291 | * | |
292 | * Dereference the line discipline for the terminal and take a | |
293 | * reference to it. If the line discipline is in flux then | |
294 | * wait patiently until it changes. | |
295 | * | |
296 | * Note: Must not be called from an IRQ/timer context. The caller | |
297 | * must also be careful not to hold other locks that will deadlock | |
298 | * against a discipline change, such as an existing ldisc reference | |
299 | * (which we check for) | |
300 | * | |
137084bb | 301 | * Locking: call functions take tty_ldiscs_lock |
01e1abb2 AC |
302 | */ |
303 | ||
304 | struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) | |
305 | { | |
65b77046 LT |
306 | struct tty_ldisc *ld; |
307 | ||
01e1abb2 | 308 | /* wait_event is a macro */ |
65b77046 LT |
309 | wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL); |
310 | return ld; | |
01e1abb2 | 311 | } |
01e1abb2 AC |
312 | EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); |
313 | ||
314 | /** | |
315 | * tty_ldisc_ref - get the tty ldisc | |
316 | * @tty: tty device | |
317 | * | |
318 | * Dereference the line discipline for the terminal and take a | |
319 | * reference to it. If the line discipline is in flux then | |
320 | * return NULL. Can be called from IRQ and timer functions. | |
321 | * | |
137084bb | 322 | * Locking: called functions take tty_ldiscs_lock |
01e1abb2 AC |
323 | */ |
324 | ||
325 | struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) | |
326 | { | |
65b77046 | 327 | return tty_ldisc_try(tty); |
01e1abb2 | 328 | } |
01e1abb2 AC |
329 | EXPORT_SYMBOL_GPL(tty_ldisc_ref); |
330 | ||
331 | /** | |
332 | * tty_ldisc_deref - free a tty ldisc reference | |
333 | * @ld: reference to free up | |
334 | * | |
335 | * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May | |
336 | * be called in IRQ context. | |
337 | * | |
137084bb | 338 | * Locking: takes tty_ldiscs_lock |
01e1abb2 AC |
339 | */ |
340 | ||
341 | void tty_ldisc_deref(struct tty_ldisc *ld) | |
342 | { | |
ebc9baed PH |
343 | unsigned long flags; |
344 | ||
345 | if (WARN_ON_ONCE(!ld)) | |
346 | return; | |
347 | ||
137084bb | 348 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
ebc9baed PH |
349 | /* |
350 | * WARNs if one-too-many reader references were released | |
351 | * - the last reference must be released with tty_ldisc_put | |
352 | */ | |
353 | WARN_ON(atomic_dec_and_test(&ld->users)); | |
137084bb | 354 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
ebc9baed PH |
355 | |
356 | if (waitqueue_active(&ld->wq_idle)) | |
357 | wake_up(&ld->wq_idle); | |
01e1abb2 | 358 | } |
01e1abb2 AC |
359 | EXPORT_SYMBOL_GPL(tty_ldisc_deref); |
360 | ||
d2c43890 PH |
361 | |
362 | static inline int __lockfunc | |
363 | tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) | |
364 | { | |
365 | return ldsem_down_write(&tty->ldisc_sem, timeout); | |
366 | } | |
367 | ||
368 | static inline int __lockfunc | |
369 | tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) | |
370 | { | |
371 | return ldsem_down_write_nested(&tty->ldisc_sem, | |
372 | LDISC_SEM_OTHER, timeout); | |
373 | } | |
374 | ||
375 | static inline void tty_ldisc_unlock(struct tty_struct *tty) | |
376 | { | |
377 | return ldsem_up_write(&tty->ldisc_sem); | |
378 | } | |
379 | ||
380 | static int __lockfunc | |
381 | tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, | |
382 | unsigned long timeout) | |
383 | { | |
384 | int ret; | |
385 | ||
386 | if (tty < tty2) { | |
387 | ret = tty_ldisc_lock(tty, timeout); | |
388 | if (ret) { | |
389 | ret = tty_ldisc_lock_nested(tty2, timeout); | |
390 | if (!ret) | |
391 | tty_ldisc_unlock(tty); | |
392 | } | |
393 | } else { | |
394 | /* if this is possible, it has lots of implications */ | |
395 | WARN_ON_ONCE(tty == tty2); | |
396 | if (tty2 && tty != tty2) { | |
397 | ret = tty_ldisc_lock(tty2, timeout); | |
398 | if (ret) { | |
399 | ret = tty_ldisc_lock_nested(tty, timeout); | |
400 | if (!ret) | |
401 | tty_ldisc_unlock(tty2); | |
402 | } | |
403 | } else | |
404 | ret = tty_ldisc_lock(tty, timeout); | |
405 | } | |
406 | ||
407 | if (!ret) | |
408 | return -EBUSY; | |
409 | ||
410 | set_bit(TTY_LDISC_HALTED, &tty->flags); | |
411 | if (tty2) | |
412 | set_bit(TTY_LDISC_HALTED, &tty2->flags); | |
413 | return 0; | |
414 | } | |
415 | ||
416 | static void __lockfunc | |
417 | tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) | |
418 | { | |
419 | tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); | |
420 | } | |
421 | ||
422 | static void __lockfunc tty_ldisc_unlock_pair(struct tty_struct *tty, | |
423 | struct tty_struct *tty2) | |
424 | { | |
425 | tty_ldisc_unlock(tty); | |
426 | if (tty2) | |
427 | tty_ldisc_unlock(tty2); | |
428 | } | |
429 | ||
430 | static void __lockfunc tty_ldisc_enable_pair(struct tty_struct *tty, | |
431 | struct tty_struct *tty2) | |
432 | { | |
433 | clear_bit(TTY_LDISC_HALTED, &tty->flags); | |
434 | if (tty2) | |
435 | clear_bit(TTY_LDISC_HALTED, &tty2->flags); | |
436 | ||
437 | tty_ldisc_unlock_pair(tty, tty2); | |
438 | } | |
439 | ||
440 | ||
01e1abb2 AC |
441 | /** |
442 | * tty_ldisc_enable - allow ldisc use | |
443 | * @tty: terminal to activate ldisc on | |
444 | * | |
445 | * Set the TTY_LDISC flag when the line discipline can be called | |
c9b3976e AC |
446 | * again. Do necessary wakeups for existing sleepers. Clear the LDISC |
447 | * changing flag to indicate any ldisc change is now over. | |
01e1abb2 | 448 | * |
c9b3976e AC |
449 | * Note: nobody should set the TTY_LDISC bit except via this function. |
450 | * Clearing directly is allowed. | |
01e1abb2 AC |
451 | */ |
452 | ||
d9121566 | 453 | static void tty_ldisc_enable(struct tty_struct *tty) |
01e1abb2 | 454 | { |
21622939 | 455 | clear_bit(TTY_LDISC_HALTED, &tty->flags); |
01e1abb2 | 456 | set_bit(TTY_LDISC, &tty->flags); |
c9b3976e | 457 | clear_bit(TTY_LDISC_CHANGING, &tty->flags); |
01e1abb2 AC |
458 | wake_up(&tty_ldisc_wait); |
459 | } | |
460 | ||
f2c4c65c AC |
461 | /** |
462 | * tty_ldisc_flush - flush line discipline queue | |
463 | * @tty: tty | |
464 | * | |
465 | * Flush the line discipline queue (if any) for this tty. If there | |
466 | * is no line discipline active this is a no-op. | |
467 | */ | |
468 | ||
469 | void tty_ldisc_flush(struct tty_struct *tty) | |
470 | { | |
471 | struct tty_ldisc *ld = tty_ldisc_ref(tty); | |
472 | if (ld) { | |
473 | if (ld->ops->flush_buffer) | |
474 | ld->ops->flush_buffer(tty); | |
475 | tty_ldisc_deref(ld); | |
476 | } | |
477 | tty_buffer_flush(tty); | |
478 | } | |
f2c4c65c AC |
479 | EXPORT_SYMBOL_GPL(tty_ldisc_flush); |
480 | ||
01e1abb2 AC |
481 | /** |
482 | * tty_set_termios_ldisc - set ldisc field | |
483 | * @tty: tty structure | |
484 | * @num: line discipline number | |
485 | * | |
486 | * This is probably overkill for real world processors but | |
487 | * they are not on hot paths so a little discipline won't do | |
488 | * any harm. | |
489 | * | |
490 | * Locking: takes termios_mutex | |
491 | */ | |
492 | ||
493 | static void tty_set_termios_ldisc(struct tty_struct *tty, int num) | |
494 | { | |
495 | mutex_lock(&tty->termios_mutex); | |
adc8d746 | 496 | tty->termios.c_line = num; |
01e1abb2 AC |
497 | mutex_unlock(&tty->termios_mutex); |
498 | } | |
499 | ||
c65c9bc3 AC |
500 | /** |
501 | * tty_ldisc_open - open a line discipline | |
502 | * @tty: tty we are opening the ldisc on | |
503 | * @ld: discipline to open | |
504 | * | |
505 | * A helper opening method. Also a convenient debugging and check | |
506 | * point. | |
ec79d605 AB |
507 | * |
508 | * Locking: always called with BTM already held. | |
c65c9bc3 AC |
509 | */ |
510 | ||
511 | static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) | |
512 | { | |
513 | WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); | |
f18f9498 AC |
514 | if (ld->ops->open) { |
515 | int ret; | |
ec79d605 | 516 | /* BTM here locks versus a hangup event */ |
f18f9498 | 517 | ret = ld->ops->open(tty); |
7f90cfc5 JS |
518 | if (ret) |
519 | clear_bit(TTY_LDISC_OPEN, &tty->flags); | |
f18f9498 AC |
520 | return ret; |
521 | } | |
c65c9bc3 AC |
522 | return 0; |
523 | } | |
524 | ||
525 | /** | |
526 | * tty_ldisc_close - close a line discipline | |
527 | * @tty: tty we are opening the ldisc on | |
528 | * @ld: discipline to close | |
529 | * | |
530 | * A helper close method. Also a convenient debugging and check | |
531 | * point. | |
532 | */ | |
533 | ||
534 | static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) | |
535 | { | |
536 | WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); | |
537 | clear_bit(TTY_LDISC_OPEN, &tty->flags); | |
538 | if (ld->ops->close) | |
539 | ld->ops->close(tty); | |
540 | } | |
01e1abb2 AC |
541 | |
542 | /** | |
543 | * tty_ldisc_restore - helper for tty ldisc change | |
544 | * @tty: tty to recover | |
545 | * @old: previous ldisc | |
546 | * | |
547 | * Restore the previous line discipline or N_TTY when a line discipline | |
548 | * change fails due to an open error | |
549 | */ | |
550 | ||
551 | static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) | |
552 | { | |
553 | char buf[64]; | |
c65c9bc3 AC |
554 | struct tty_ldisc *new_ldisc; |
555 | int r; | |
01e1abb2 AC |
556 | |
557 | /* There is an outstanding reference here so this is safe */ | |
c65c9bc3 AC |
558 | old = tty_ldisc_get(old->ops->num); |
559 | WARN_ON(IS_ERR(old)); | |
f4807045 | 560 | tty->ldisc = old; |
01e1abb2 | 561 | tty_set_termios_ldisc(tty, old->ops->num); |
c65c9bc3 AC |
562 | if (tty_ldisc_open(tty, old) < 0) { |
563 | tty_ldisc_put(old); | |
01e1abb2 | 564 | /* This driver is always present */ |
852e99d2 | 565 | new_ldisc = tty_ldisc_get(N_TTY); |
c65c9bc3 | 566 | if (IS_ERR(new_ldisc)) |
01e1abb2 | 567 | panic("n_tty: get"); |
f4807045 | 568 | tty->ldisc = new_ldisc; |
01e1abb2 | 569 | tty_set_termios_ldisc(tty, N_TTY); |
c65c9bc3 AC |
570 | r = tty_ldisc_open(tty, new_ldisc); |
571 | if (r < 0) | |
572 | panic("Couldn't open N_TTY ldisc for " | |
573 | "%s --- error %d.", | |
574 | tty_name(tty, buf), r); | |
01e1abb2 AC |
575 | } |
576 | } | |
577 | ||
100eeae2 JS |
578 | /** |
579 | * tty_ldisc_wait_idle - wait for the ldisc to become idle | |
580 | * @tty: tty to wait for | |
df92d056 | 581 | * @timeout: for how long to wait at most |
100eeae2 JS |
582 | * |
583 | * Wait for the line discipline to become idle. The discipline must | |
584 | * have been halted for this to guarantee it remains idle. | |
585 | */ | |
df92d056 | 586 | static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) |
100eeae2 | 587 | { |
df92d056 | 588 | long ret; |
1541f845 | 589 | ret = wait_event_timeout(tty->ldisc->wq_idle, |
df92d056 | 590 | atomic_read(&tty->ldisc->users) == 1, timeout); |
100eeae2 JS |
591 | return ret > 0 ? 0 : -EBUSY; |
592 | } | |
593 | ||
11cf48ea PH |
594 | /** |
595 | * tty_ldisc_halt - shut down the line discipline | |
596 | * @tty: tty device | |
f4cf7a38 | 597 | * @o_tty: paired pty device (can be NULL) |
cf528476 | 598 | * @timeout: # of jiffies to wait for ldisc refs to be released |
11cf48ea | 599 | * |
f4cf7a38 PH |
600 | * Shut down the line discipline and work queue for this tty device and |
601 | * its paired pty (if exists). Clearing the TTY_LDISC flag ensures | |
4f98d467 PH |
602 | * no further references can be obtained, while waiting for existing |
603 | * references to be released ensures no more data is fed to the ldisc. | |
cf528476 | 604 | * |
11cf48ea PH |
605 | * You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex) |
606 | * in order to make sure any currently executing ldisc work is also | |
607 | * flushed. | |
608 | */ | |
609 | ||
f4cf7a38 | 610 | static int tty_ldisc_halt(struct tty_struct *tty, struct tty_struct *o_tty, |
4f98d467 | 611 | long timeout) |
11cf48ea | 612 | { |
4f98d467 | 613 | int retval; |
cf528476 | 614 | |
11cf48ea | 615 | clear_bit(TTY_LDISC, &tty->flags); |
f4cf7a38 PH |
616 | if (o_tty) |
617 | clear_bit(TTY_LDISC, &o_tty->flags); | |
618 | ||
cf528476 | 619 | retval = tty_ldisc_wait_idle(tty, timeout); |
f4cf7a38 PH |
620 | if (!retval && o_tty) |
621 | retval = tty_ldisc_wait_idle(o_tty, timeout); | |
cf528476 PH |
622 | if (retval) |
623 | return retval; | |
624 | ||
11cf48ea | 625 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
4f98d467 | 626 | if (o_tty) |
f4cf7a38 | 627 | set_bit(TTY_LDISC_HALTED, &o_tty->flags); |
f4cf7a38 | 628 | |
cf528476 | 629 | return 0; |
11cf48ea PH |
630 | } |
631 | ||
168942c9 | 632 | /** |
76bc35e7 PH |
633 | * tty_ldisc_hangup_halt - halt the line discipline for hangup |
634 | * @tty: tty being hung up | |
168942c9 | 635 | * |
76bc35e7 PH |
636 | * Shut down the line discipline and work queue for the tty device |
637 | * being hungup. Clear the TTY_LDISC flag to ensure no further | |
4f98d467 PH |
638 | * references can be obtained and wait for remaining references to be |
639 | * released to ensure no more data is fed to this ldisc. | |
168942c9 | 640 | * Caller must hold legacy and ->ldisc_mutex. |
2276ad97 PH |
641 | * |
642 | * NB: tty_set_ldisc() is prevented from changing the ldisc concurrently | |
643 | * with this function by checking the TTY_HUPPING flag. | |
168942c9 | 644 | */ |
76bc35e7 | 645 | static bool tty_ldisc_hangup_halt(struct tty_struct *tty) |
168942c9 | 646 | { |
2276ad97 PH |
647 | char cur_n[TASK_COMM_LEN], tty_n[64]; |
648 | long timeout = 3 * HZ; | |
649 | ||
76bc35e7 PH |
650 | clear_bit(TTY_LDISC, &tty->flags); |
651 | ||
2276ad97 PH |
652 | if (tty->ldisc) { /* Not yet closed */ |
653 | tty_unlock(tty); | |
654 | ||
655 | while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { | |
656 | timeout = MAX_SCHEDULE_TIMEOUT; | |
657 | printk_ratelimited(KERN_WARNING | |
658 | "%s: waiting (%s) for %s took too long, but we keep waiting...\n", | |
659 | __func__, get_task_comm(cur_n, current), | |
660 | tty_name(tty, tty_n)); | |
168942c9 | 661 | } |
76bc35e7 | 662 | |
76bc35e7 PH |
663 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
664 | ||
2276ad97 PH |
665 | /* must reacquire both locks and preserve lock order */ |
666 | mutex_unlock(&tty->ldisc_mutex); | |
667 | tty_lock(tty); | |
668 | mutex_lock(&tty->ldisc_mutex); | |
168942c9 PH |
669 | } |
670 | return !!tty->ldisc; | |
671 | } | |
672 | ||
01e1abb2 AC |
673 | /** |
674 | * tty_set_ldisc - set line discipline | |
675 | * @tty: the terminal to set | |
676 | * @ldisc: the line discipline | |
677 | * | |
678 | * Set the discipline of a tty line. Must be called from a process | |
c65c9bc3 AC |
679 | * context. The ldisc change logic has to protect itself against any |
680 | * overlapping ldisc change (including on the other end of pty pairs), | |
681 | * the close of one side of a tty/pty pair, and eventually hangup. | |
01e1abb2 | 682 | * |
137084bb | 683 | * Locking: takes tty_ldiscs_lock, termios_mutex |
01e1abb2 AC |
684 | */ |
685 | ||
686 | int tty_set_ldisc(struct tty_struct *tty, int ldisc) | |
687 | { | |
688 | int retval; | |
c65c9bc3 | 689 | struct tty_ldisc *o_ldisc, *new_ldisc; |
01e1abb2 AC |
690 | struct tty_struct *o_tty; |
691 | ||
c65c9bc3 AC |
692 | new_ldisc = tty_ldisc_get(ldisc); |
693 | if (IS_ERR(new_ldisc)) | |
694 | return PTR_ERR(new_ldisc); | |
01e1abb2 | 695 | |
89c8d91e | 696 | tty_lock(tty); |
01e1abb2 | 697 | /* |
c65c9bc3 AC |
698 | * We need to look at the tty locking here for pty/tty pairs |
699 | * when both sides try to change in parallel. | |
01e1abb2 AC |
700 | */ |
701 | ||
c65c9bc3 AC |
702 | o_tty = tty->link; /* o_tty is the pty side or NULL */ |
703 | ||
01e1abb2 | 704 | |
c65c9bc3 AC |
705 | /* |
706 | * Check the no-op case | |
707 | */ | |
708 | ||
709 | if (tty->ldisc->ops->num == ldisc) { | |
89c8d91e | 710 | tty_unlock(tty); |
c65c9bc3 | 711 | tty_ldisc_put(new_ldisc); |
01e1abb2 AC |
712 | return 0; |
713 | } | |
714 | ||
c65c9bc3 AC |
715 | mutex_lock(&tty->ldisc_mutex); |
716 | ||
717 | /* | |
718 | * We could be midstream of another ldisc change which has | |
719 | * dropped the lock during processing. If so we need to wait. | |
720 | */ | |
721 | ||
722 | while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { | |
723 | mutex_unlock(&tty->ldisc_mutex); | |
89c8d91e | 724 | tty_unlock(tty); |
c65c9bc3 AC |
725 | wait_event(tty_ldisc_wait, |
726 | test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); | |
89c8d91e | 727 | tty_lock(tty); |
c65c9bc3 AC |
728 | mutex_lock(&tty->ldisc_mutex); |
729 | } | |
eeb89d91 | 730 | |
c65c9bc3 | 731 | set_bit(TTY_LDISC_CHANGING, &tty->flags); |
852e99d2 | 732 | |
01e1abb2 AC |
733 | /* |
734 | * No more input please, we are switching. The new ldisc | |
735 | * will update this value in the ldisc open function | |
736 | */ | |
737 | ||
738 | tty->receive_room = 0; | |
739 | ||
740 | o_ldisc = tty->ldisc; | |
eeb89d91 | 741 | |
89c8d91e | 742 | tty_unlock(tty); |
01e1abb2 AC |
743 | /* |
744 | * Make sure we don't change while someone holds a | |
745 | * reference to the line discipline. The TTY_LDISC bit | |
746 | * prevents anyone taking a reference once it is clear. | |
747 | * We need the lock to avoid racing reference takers. | |
c9b3976e AC |
748 | * |
749 | * We must clear the TTY_LDISC bit here to avoid a livelock | |
750 | * with a userspace app continually trying to use the tty in | |
751 | * parallel to the change and re-referencing the tty. | |
01e1abb2 AC |
752 | */ |
753 | ||
4f98d467 | 754 | retval = tty_ldisc_halt(tty, o_tty, 5 * HZ); |
01e1abb2 | 755 | |
01e1abb2 | 756 | /* |
a2965b7b | 757 | * Wait for hangup to complete, if pending. |
c65c9bc3 | 758 | * We must drop the mutex here in case a hangup is also in process. |
01e1abb2 | 759 | */ |
c65c9bc3 AC |
760 | |
761 | mutex_unlock(&tty->ldisc_mutex); | |
762 | ||
a2965b7b | 763 | flush_work(&tty->hangup_work); |
c65c9bc3 | 764 | |
89c8d91e | 765 | tty_lock(tty); |
60af22d2 | 766 | mutex_lock(&tty->ldisc_mutex); |
100eeae2 JS |
767 | |
768 | /* handle wait idle failure locked */ | |
769 | if (retval) { | |
770 | tty_ldisc_put(new_ldisc); | |
771 | goto enable; | |
772 | } | |
773 | ||
40c9f61e | 774 | if (test_bit(TTY_HUPPING, &tty->flags)) { |
c65c9bc3 AC |
775 | /* We were raced by the hangup method. It will have stomped |
776 | the ldisc data and closed the ldisc down */ | |
777 | clear_bit(TTY_LDISC_CHANGING, &tty->flags); | |
778 | mutex_unlock(&tty->ldisc_mutex); | |
779 | tty_ldisc_put(new_ldisc); | |
89c8d91e | 780 | tty_unlock(tty); |
c65c9bc3 AC |
781 | return -EIO; |
782 | } | |
783 | ||
01e1abb2 | 784 | /* Shutdown the current discipline. */ |
c65c9bc3 | 785 | tty_ldisc_close(tty, o_ldisc); |
01e1abb2 AC |
786 | |
787 | /* Now set up the new line discipline. */ | |
f4807045 | 788 | tty->ldisc = new_ldisc; |
01e1abb2 | 789 | tty_set_termios_ldisc(tty, ldisc); |
c65c9bc3 AC |
790 | |
791 | retval = tty_ldisc_open(tty, new_ldisc); | |
01e1abb2 | 792 | if (retval < 0) { |
c65c9bc3 AC |
793 | /* Back to the old one or N_TTY if we can't */ |
794 | tty_ldisc_put(new_ldisc); | |
795 | tty_ldisc_restore(tty, o_ldisc); | |
01e1abb2 | 796 | } |
c65c9bc3 | 797 | |
01e1abb2 AC |
798 | /* At this point we hold a reference to the new ldisc and a |
799 | a reference to the old ldisc. If we ended up flipping back | |
800 | to the existing ldisc we have two references to it */ | |
801 | ||
c65c9bc3 | 802 | if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc) |
01e1abb2 AC |
803 | tty->ops->set_ldisc(tty); |
804 | ||
c65c9bc3 | 805 | tty_ldisc_put(o_ldisc); |
01e1abb2 | 806 | |
100eeae2 | 807 | enable: |
01e1abb2 | 808 | /* |
c65c9bc3 | 809 | * Allow ldisc referencing to occur again |
01e1abb2 AC |
810 | */ |
811 | ||
812 | tty_ldisc_enable(tty); | |
813 | if (o_tty) | |
814 | tty_ldisc_enable(o_tty); | |
815 | ||
c65c9bc3 | 816 | /* Restart the work queue in case no characters kick it off. Safe if |
01e1abb2 | 817 | already running */ |
4f98d467 PH |
818 | schedule_work(&tty->port->buf.work); |
819 | if (o_tty) | |
ecbbfd44 | 820 | schedule_work(&o_tty->port->buf.work); |
4f98d467 | 821 | |
c65c9bc3 | 822 | mutex_unlock(&tty->ldisc_mutex); |
89c8d91e | 823 | tty_unlock(tty); |
01e1abb2 AC |
824 | return retval; |
825 | } | |
826 | ||
c65c9bc3 AC |
827 | /** |
828 | * tty_reset_termios - reset terminal state | |
829 | * @tty: tty to reset | |
830 | * | |
831 | * Restore a terminal to the driver default state. | |
832 | */ | |
833 | ||
834 | static void tty_reset_termios(struct tty_struct *tty) | |
835 | { | |
836 | mutex_lock(&tty->termios_mutex); | |
adc8d746 AC |
837 | tty->termios = tty->driver->init_termios; |
838 | tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); | |
839 | tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); | |
c65c9bc3 AC |
840 | mutex_unlock(&tty->termios_mutex); |
841 | } | |
842 | ||
843 | ||
844 | /** | |
845 | * tty_ldisc_reinit - reinitialise the tty ldisc | |
846 | * @tty: tty to reinit | |
638b9648 | 847 | * @ldisc: line discipline to reinitialize |
c65c9bc3 | 848 | * |
638b9648 AC |
849 | * Switch the tty to a line discipline and leave the ldisc |
850 | * state closed | |
c65c9bc3 AC |
851 | */ |
852 | ||
1c95ba1e | 853 | static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) |
c65c9bc3 | 854 | { |
1c95ba1e PR |
855 | struct tty_ldisc *ld = tty_ldisc_get(ldisc); |
856 | ||
857 | if (IS_ERR(ld)) | |
858 | return -1; | |
c65c9bc3 AC |
859 | |
860 | tty_ldisc_close(tty, tty->ldisc); | |
861 | tty_ldisc_put(tty->ldisc); | |
c65c9bc3 AC |
862 | /* |
863 | * Switch the line discipline back | |
864 | */ | |
f4807045 | 865 | tty->ldisc = ld; |
638b9648 | 866 | tty_set_termios_ldisc(tty, ldisc); |
1c95ba1e PR |
867 | |
868 | return 0; | |
c65c9bc3 AC |
869 | } |
870 | ||
871 | /** | |
872 | * tty_ldisc_hangup - hangup ldisc reset | |
873 | * @tty: tty being hung up | |
874 | * | |
875 | * Some tty devices reset their termios when they receive a hangup | |
876 | * event. In that situation we must also switch back to N_TTY properly | |
877 | * before we reset the termios data. | |
878 | * | |
879 | * Locking: We can take the ldisc mutex as the rest of the code is | |
880 | * careful to allow for this. | |
881 | * | |
882 | * In the pty pair case this occurs in the close() path of the | |
883 | * tty itself so we must be careful about locking rules. | |
884 | */ | |
885 | ||
886 | void tty_ldisc_hangup(struct tty_struct *tty) | |
887 | { | |
888 | struct tty_ldisc *ld; | |
638b9648 AC |
889 | int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; |
890 | int err = 0; | |
c65c9bc3 | 891 | |
fc575ee6 PH |
892 | tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); |
893 | ||
c65c9bc3 AC |
894 | /* |
895 | * FIXME! What are the locking issues here? This may me overdoing | |
896 | * things... This question is especially important now that we've | |
897 | * removed the irqlock. | |
898 | */ | |
899 | ld = tty_ldisc_ref(tty); | |
900 | if (ld != NULL) { | |
901 | /* We may have no line discipline at this point */ | |
902 | if (ld->ops->flush_buffer) | |
903 | ld->ops->flush_buffer(tty); | |
904 | tty_driver_flush_buffer(tty); | |
905 | if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && | |
906 | ld->ops->write_wakeup) | |
907 | ld->ops->write_wakeup(tty); | |
908 | if (ld->ops->hangup) | |
909 | ld->ops->hangup(tty); | |
910 | tty_ldisc_deref(ld); | |
911 | } | |
912 | /* | |
913 | * FIXME: Once we trust the LDISC code better we can wait here for | |
914 | * ldisc completion and fix the driver call race | |
915 | */ | |
916 | wake_up_interruptible_poll(&tty->write_wait, POLLOUT); | |
917 | wake_up_interruptible_poll(&tty->read_wait, POLLIN); | |
918 | /* | |
919 | * Shutdown the current line discipline, and reset it to | |
638b9648 AC |
920 | * N_TTY if need be. |
921 | * | |
922 | * Avoid racing set_ldisc or tty_ldisc_release | |
c65c9bc3 | 923 | */ |
638b9648 | 924 | mutex_lock(&tty->ldisc_mutex); |
60af22d2 | 925 | |
76bc35e7 | 926 | if (tty_ldisc_hangup_halt(tty)) { |
c8785241 PH |
927 | |
928 | /* At this point we have a halted ldisc; we want to close it and | |
929 | reopen a new ldisc. We could defer the reopen to the next | |
930 | open but it means auditing a lot of other paths so this is | |
931 | a FIXME */ | |
638b9648 | 932 | if (reset == 0) { |
1c95ba1e | 933 | |
adc8d746 | 934 | if (!tty_ldisc_reinit(tty, tty->termios.c_line)) |
1c95ba1e PR |
935 | err = tty_ldisc_open(tty, tty->ldisc); |
936 | else | |
937 | err = 1; | |
638b9648 AC |
938 | } |
939 | /* If the re-open fails or we reset then go to N_TTY. The | |
940 | N_TTY open cannot fail */ | |
941 | if (reset || err) { | |
1c95ba1e | 942 | BUG_ON(tty_ldisc_reinit(tty, N_TTY)); |
c8d50041 | 943 | WARN_ON(tty_ldisc_open(tty, tty->ldisc)); |
c8d50041 | 944 | } |
638b9648 | 945 | tty_ldisc_enable(tty); |
c65c9bc3 | 946 | } |
638b9648 AC |
947 | mutex_unlock(&tty->ldisc_mutex); |
948 | if (reset) | |
949 | tty_reset_termios(tty); | |
fc575ee6 PH |
950 | |
951 | tty_ldisc_debug(tty, "re-opened ldisc: %p\n", tty->ldisc); | |
c65c9bc3 | 952 | } |
01e1abb2 AC |
953 | |
954 | /** | |
955 | * tty_ldisc_setup - open line discipline | |
956 | * @tty: tty being shut down | |
957 | * @o_tty: pair tty for pty/tty pairs | |
958 | * | |
959 | * Called during the initial open of a tty/pty pair in order to set up the | |
c65c9bc3 AC |
960 | * line disciplines and bind them to the tty. This has no locking issues |
961 | * as the device isn't yet active. | |
01e1abb2 AC |
962 | */ |
963 | ||
964 | int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) | |
965 | { | |
c65c9bc3 | 966 | struct tty_ldisc *ld = tty->ldisc; |
01e1abb2 AC |
967 | int retval; |
968 | ||
c65c9bc3 AC |
969 | retval = tty_ldisc_open(tty, ld); |
970 | if (retval) | |
971 | return retval; | |
972 | ||
973 | if (o_tty) { | |
974 | retval = tty_ldisc_open(o_tty, o_tty->ldisc); | |
01e1abb2 | 975 | if (retval) { |
c65c9bc3 | 976 | tty_ldisc_close(tty, ld); |
01e1abb2 AC |
977 | return retval; |
978 | } | |
979 | tty_ldisc_enable(o_tty); | |
980 | } | |
981 | tty_ldisc_enable(tty); | |
982 | return 0; | |
983 | } | |
89c8d91e AC |
984 | |
985 | static void tty_ldisc_kill(struct tty_struct *tty) | |
986 | { | |
987 | mutex_lock(&tty->ldisc_mutex); | |
988 | /* | |
989 | * Now kill off the ldisc | |
990 | */ | |
991 | tty_ldisc_close(tty, tty->ldisc); | |
992 | tty_ldisc_put(tty->ldisc); | |
993 | /* Force an oops if we mess this up */ | |
994 | tty->ldisc = NULL; | |
995 | ||
996 | /* Ensure the next open requests the N_TTY ldisc */ | |
997 | tty_set_termios_ldisc(tty, N_TTY); | |
998 | mutex_unlock(&tty->ldisc_mutex); | |
999 | } | |
1000 | ||
01e1abb2 AC |
1001 | /** |
1002 | * tty_ldisc_release - release line discipline | |
1003 | * @tty: tty being shut down | |
1004 | * @o_tty: pair tty for pty/tty pairs | |
1005 | * | |
852e99d2 AC |
1006 | * Called during the final close of a tty/pty pair in order to shut down |
1007 | * the line discpline layer. On exit the ldisc assigned is N_TTY and the | |
c65c9bc3 | 1008 | * ldisc has not been opened. |
01e1abb2 AC |
1009 | */ |
1010 | ||
1011 | void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) | |
1012 | { | |
01e1abb2 | 1013 | /* |
a2965b7b PH |
1014 | * Shutdown this line discipline. As this is the final close, |
1015 | * it does not race with the set_ldisc code path. | |
01e1abb2 | 1016 | */ |
01e1abb2 | 1017 | |
fc575ee6 PH |
1018 | tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); |
1019 | ||
4f98d467 | 1020 | tty_ldisc_halt(tty, o_tty, MAX_SCHEDULE_TIMEOUT); |
d155255a | 1021 | |
852e4a81 | 1022 | tty_lock_pair(tty, o_tty); |
6d31a88c | 1023 | /* This will need doing differently if we need to lock */ |
89c8d91e | 1024 | tty_ldisc_kill(tty); |
c65c9bc3 | 1025 | if (o_tty) |
89c8d91e | 1026 | tty_ldisc_kill(o_tty); |
aef29bc2 | 1027 | |
89c8d91e | 1028 | tty_unlock_pair(tty, o_tty); |
aef29bc2 AC |
1029 | /* And the memory resources remaining (buffers, termios) will be |
1030 | disposed of when the kref hits zero */ | |
fc575ee6 PH |
1031 | |
1032 | tty_ldisc_debug(tty, "ldisc closed\n"); | |
01e1abb2 AC |
1033 | } |
1034 | ||
1035 | /** | |
1036 | * tty_ldisc_init - ldisc setup for new tty | |
1037 | * @tty: tty being allocated | |
1038 | * | |
1039 | * Set up the line discipline objects for a newly allocated tty. Note that | |
1040 | * the tty structure is not completely set up when this call is made. | |
1041 | */ | |
1042 | ||
1043 | void tty_ldisc_init(struct tty_struct *tty) | |
1044 | { | |
c65c9bc3 AC |
1045 | struct tty_ldisc *ld = tty_ldisc_get(N_TTY); |
1046 | if (IS_ERR(ld)) | |
01e1abb2 | 1047 | panic("n_tty: init_tty"); |
f4807045 | 1048 | tty->ldisc = ld; |
01e1abb2 AC |
1049 | } |
1050 | ||
6716671d JS |
1051 | /** |
1052 | * tty_ldisc_init - ldisc cleanup for new tty | |
1053 | * @tty: tty that was allocated recently | |
1054 | * | |
1055 | * The tty structure must not becompletely set up (tty_ldisc_setup) when | |
1056 | * this call is made. | |
1057 | */ | |
1058 | void tty_ldisc_deinit(struct tty_struct *tty) | |
1059 | { | |
ebc9baed | 1060 | tty_ldisc_put(tty->ldisc); |
f4807045 | 1061 | tty->ldisc = NULL; |
6716671d JS |
1062 | } |
1063 | ||
01e1abb2 AC |
1064 | void tty_ldisc_begin(void) |
1065 | { | |
1066 | /* Setup the default TTY line discipline. */ | |
1067 | (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); | |
1068 | } |