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 | /* Line disc dispatch table */ |
49 | static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; | |
50 | ||
51 | /** | |
52 | * tty_register_ldisc - install a line discipline | |
53 | * @disc: ldisc number | |
54 | * @new_ldisc: pointer to the ldisc object | |
55 | * | |
56 | * Installs a new line discipline into the kernel. The discipline | |
57 | * is set up as unreferenced and then made available to the kernel | |
58 | * from this point onwards. | |
59 | * | |
60 | * Locking: | |
137084bb | 61 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
62 | */ |
63 | ||
64 | int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) | |
65 | { | |
66 | unsigned long flags; | |
67 | int ret = 0; | |
68 | ||
69 | if (disc < N_TTY || disc >= NR_LDISCS) | |
70 | return -EINVAL; | |
71 | ||
137084bb | 72 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
73 | tty_ldiscs[disc] = new_ldisc; |
74 | new_ldisc->num = disc; | |
75 | new_ldisc->refcount = 0; | |
137084bb | 76 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
77 | |
78 | return ret; | |
79 | } | |
80 | EXPORT_SYMBOL(tty_register_ldisc); | |
81 | ||
82 | /** | |
83 | * tty_unregister_ldisc - unload a line discipline | |
84 | * @disc: ldisc number | |
85 | * @new_ldisc: pointer to the ldisc object | |
86 | * | |
87 | * Remove a line discipline from the kernel providing it is not | |
88 | * currently in use. | |
89 | * | |
90 | * Locking: | |
137084bb | 91 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
92 | */ |
93 | ||
94 | int tty_unregister_ldisc(int disc) | |
95 | { | |
96 | unsigned long flags; | |
97 | int ret = 0; | |
98 | ||
99 | if (disc < N_TTY || disc >= NR_LDISCS) | |
100 | return -EINVAL; | |
101 | ||
137084bb | 102 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
103 | if (tty_ldiscs[disc]->refcount) |
104 | ret = -EBUSY; | |
105 | else | |
106 | tty_ldiscs[disc] = NULL; | |
137084bb | 107 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
01e1abb2 AC |
108 | |
109 | return ret; | |
110 | } | |
111 | EXPORT_SYMBOL(tty_unregister_ldisc); | |
112 | ||
f0de0e8d LT |
113 | static struct tty_ldisc_ops *get_ldops(int disc) |
114 | { | |
115 | unsigned long flags; | |
116 | struct tty_ldisc_ops *ldops, *ret; | |
117 | ||
137084bb | 118 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
119 | ret = ERR_PTR(-EINVAL); |
120 | ldops = tty_ldiscs[disc]; | |
121 | if (ldops) { | |
122 | ret = ERR_PTR(-EAGAIN); | |
123 | if (try_module_get(ldops->owner)) { | |
124 | ldops->refcount++; | |
125 | ret = ldops; | |
126 | } | |
127 | } | |
137084bb | 128 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
129 | return ret; |
130 | } | |
131 | ||
132 | static void put_ldops(struct tty_ldisc_ops *ldops) | |
133 | { | |
134 | unsigned long flags; | |
135 | ||
137084bb | 136 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
f0de0e8d LT |
137 | ldops->refcount--; |
138 | module_put(ldops->owner); | |
137084bb | 139 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
f0de0e8d | 140 | } |
01e1abb2 | 141 | |
01e1abb2 AC |
142 | /** |
143 | * tty_ldisc_get - take a reference to an ldisc | |
144 | * @disc: ldisc number | |
01e1abb2 AC |
145 | * |
146 | * Takes a reference to a line discipline. Deals with refcounts and | |
147 | * module locking counts. Returns NULL if the discipline is not available. | |
148 | * Returns a pointer to the discipline and bumps the ref count if it is | |
149 | * available | |
150 | * | |
151 | * Locking: | |
137084bb | 152 | * takes tty_ldiscs_lock to guard against ldisc races |
01e1abb2 AC |
153 | */ |
154 | ||
36697529 | 155 | static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) |
01e1abb2 | 156 | { |
c65c9bc3 | 157 | struct tty_ldisc *ld; |
182274f8 | 158 | struct tty_ldisc_ops *ldops; |
01e1abb2 AC |
159 | |
160 | if (disc < N_TTY || disc >= NR_LDISCS) | |
c65c9bc3 | 161 | return ERR_PTR(-EINVAL); |
182274f8 LT |
162 | |
163 | /* | |
164 | * Get the ldisc ops - we may need to request them to be loaded | |
165 | * dynamically and try again. | |
166 | */ | |
167 | ldops = get_ldops(disc); | |
168 | if (IS_ERR(ldops)) { | |
01e1abb2 | 169 | request_module("tty-ldisc-%d", disc); |
182274f8 LT |
170 | ldops = get_ldops(disc); |
171 | if (IS_ERR(ldops)) | |
172 | return ERR_CAST(ldops); | |
173 | } | |
174 | ||
175 | ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); | |
176 | if (ld == NULL) { | |
177 | put_ldops(ldops); | |
178 | return ERR_PTR(-ENOMEM); | |
01e1abb2 | 179 | } |
182274f8 LT |
180 | |
181 | ld->ops = ldops; | |
36697529 | 182 | ld->tty = tty; |
1541f845 | 183 | |
c65c9bc3 | 184 | return ld; |
01e1abb2 AC |
185 | } |
186 | ||
734de249 PH |
187 | /** |
188 | * tty_ldisc_put - release the ldisc | |
189 | * | |
190 | * Complement of tty_ldisc_get(). | |
191 | */ | |
192 | static inline void tty_ldisc_put(struct tty_ldisc *ld) | |
193 | { | |
734de249 PH |
194 | if (WARN_ON_ONCE(!ld)) |
195 | return; | |
196 | ||
36697529 | 197 | put_ldops(ld->ops); |
734de249 | 198 | kfree(ld); |
734de249 PH |
199 | } |
200 | ||
852e99d2 | 201 | static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) |
01e1abb2 AC |
202 | { |
203 | return (*pos < NR_LDISCS) ? pos : NULL; | |
204 | } | |
205 | ||
852e99d2 | 206 | static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) |
01e1abb2 AC |
207 | { |
208 | (*pos)++; | |
209 | return (*pos < NR_LDISCS) ? pos : NULL; | |
210 | } | |
211 | ||
212 | static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) | |
213 | { | |
214 | } | |
215 | ||
216 | static int tty_ldiscs_seq_show(struct seq_file *m, void *v) | |
217 | { | |
218 | int i = *(loff_t *)v; | |
f0de0e8d | 219 | struct tty_ldisc_ops *ldops; |
852e99d2 | 220 | |
f0de0e8d LT |
221 | ldops = get_ldops(i); |
222 | if (IS_ERR(ldops)) | |
01e1abb2 | 223 | return 0; |
f0de0e8d LT |
224 | seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); |
225 | put_ldops(ldops); | |
01e1abb2 AC |
226 | return 0; |
227 | } | |
228 | ||
229 | static const struct seq_operations tty_ldiscs_seq_ops = { | |
230 | .start = tty_ldiscs_seq_start, | |
231 | .next = tty_ldiscs_seq_next, | |
232 | .stop = tty_ldiscs_seq_stop, | |
233 | .show = tty_ldiscs_seq_show, | |
234 | }; | |
235 | ||
236 | static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) | |
237 | { | |
238 | return seq_open(file, &tty_ldiscs_seq_ops); | |
239 | } | |
240 | ||
241 | const struct file_operations tty_ldiscs_proc_fops = { | |
242 | .owner = THIS_MODULE, | |
243 | .open = proc_tty_ldiscs_open, | |
244 | .read = seq_read, | |
245 | .llseek = seq_lseek, | |
246 | .release = seq_release, | |
247 | }; | |
248 | ||
01e1abb2 AC |
249 | /** |
250 | * tty_ldisc_ref_wait - wait for the tty ldisc | |
251 | * @tty: tty device | |
252 | * | |
253 | * Dereference the line discipline for the terminal and take a | |
254 | * reference to it. If the line discipline is in flux then | |
255 | * wait patiently until it changes. | |
256 | * | |
257 | * Note: Must not be called from an IRQ/timer context. The caller | |
258 | * must also be careful not to hold other locks that will deadlock | |
259 | * against a discipline change, such as an existing ldisc reference | |
260 | * (which we check for) | |
261 | * | |
36697529 PH |
262 | * Note: only callable from a file_operations routine (which |
263 | * guarantees tty->ldisc != NULL when the lock is acquired). | |
01e1abb2 AC |
264 | */ |
265 | ||
266 | struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) | |
267 | { | |
36697529 PH |
268 | ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); |
269 | WARN_ON(!tty->ldisc); | |
270 | return tty->ldisc; | |
01e1abb2 | 271 | } |
01e1abb2 AC |
272 | EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); |
273 | ||
274 | /** | |
275 | * tty_ldisc_ref - get the tty ldisc | |
276 | * @tty: tty device | |
277 | * | |
278 | * Dereference the line discipline for the terminal and take a | |
279 | * reference to it. If the line discipline is in flux then | |
280 | * return NULL. Can be called from IRQ and timer functions. | |
01e1abb2 AC |
281 | */ |
282 | ||
283 | struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) | |
284 | { | |
36697529 PH |
285 | struct tty_ldisc *ld = NULL; |
286 | ||
287 | if (ldsem_down_read_trylock(&tty->ldisc_sem)) { | |
288 | ld = tty->ldisc; | |
289 | if (!ld) | |
290 | ldsem_up_read(&tty->ldisc_sem); | |
291 | } | |
292 | return ld; | |
01e1abb2 | 293 | } |
01e1abb2 AC |
294 | EXPORT_SYMBOL_GPL(tty_ldisc_ref); |
295 | ||
296 | /** | |
297 | * tty_ldisc_deref - free a tty ldisc reference | |
298 | * @ld: reference to free up | |
299 | * | |
300 | * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May | |
301 | * be called in IRQ context. | |
01e1abb2 AC |
302 | */ |
303 | ||
304 | void tty_ldisc_deref(struct tty_ldisc *ld) | |
305 | { | |
36697529 | 306 | ldsem_up_read(&ld->tty->ldisc_sem); |
01e1abb2 | 307 | } |
01e1abb2 AC |
308 | EXPORT_SYMBOL_GPL(tty_ldisc_deref); |
309 | ||
d2c43890 PH |
310 | |
311 | static inline int __lockfunc | |
312 | tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) | |
313 | { | |
314 | return ldsem_down_write(&tty->ldisc_sem, timeout); | |
315 | } | |
316 | ||
317 | static inline int __lockfunc | |
318 | tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) | |
319 | { | |
320 | return ldsem_down_write_nested(&tty->ldisc_sem, | |
321 | LDISC_SEM_OTHER, timeout); | |
322 | } | |
323 | ||
324 | static inline void tty_ldisc_unlock(struct tty_struct *tty) | |
325 | { | |
326 | return ldsem_up_write(&tty->ldisc_sem); | |
327 | } | |
328 | ||
329 | static int __lockfunc | |
330 | tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, | |
331 | unsigned long timeout) | |
332 | { | |
333 | int ret; | |
334 | ||
335 | if (tty < tty2) { | |
336 | ret = tty_ldisc_lock(tty, timeout); | |
337 | if (ret) { | |
338 | ret = tty_ldisc_lock_nested(tty2, timeout); | |
339 | if (!ret) | |
340 | tty_ldisc_unlock(tty); | |
341 | } | |
342 | } else { | |
343 | /* if this is possible, it has lots of implications */ | |
344 | WARN_ON_ONCE(tty == tty2); | |
345 | if (tty2 && tty != tty2) { | |
346 | ret = tty_ldisc_lock(tty2, timeout); | |
347 | if (ret) { | |
348 | ret = tty_ldisc_lock_nested(tty, timeout); | |
349 | if (!ret) | |
350 | tty_ldisc_unlock(tty2); | |
351 | } | |
352 | } else | |
353 | ret = tty_ldisc_lock(tty, timeout); | |
354 | } | |
355 | ||
356 | if (!ret) | |
357 | return -EBUSY; | |
358 | ||
359 | set_bit(TTY_LDISC_HALTED, &tty->flags); | |
360 | if (tty2) | |
361 | set_bit(TTY_LDISC_HALTED, &tty2->flags); | |
362 | return 0; | |
363 | } | |
364 | ||
365 | static void __lockfunc | |
366 | tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) | |
367 | { | |
368 | tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); | |
369 | } | |
370 | ||
371 | static void __lockfunc tty_ldisc_unlock_pair(struct tty_struct *tty, | |
372 | struct tty_struct *tty2) | |
373 | { | |
374 | tty_ldisc_unlock(tty); | |
375 | if (tty2) | |
376 | tty_ldisc_unlock(tty2); | |
377 | } | |
378 | ||
379 | static void __lockfunc tty_ldisc_enable_pair(struct tty_struct *tty, | |
380 | struct tty_struct *tty2) | |
381 | { | |
382 | clear_bit(TTY_LDISC_HALTED, &tty->flags); | |
383 | if (tty2) | |
384 | clear_bit(TTY_LDISC_HALTED, &tty2->flags); | |
385 | ||
386 | tty_ldisc_unlock_pair(tty, tty2); | |
387 | } | |
388 | ||
f2c4c65c AC |
389 | /** |
390 | * tty_ldisc_flush - flush line discipline queue | |
391 | * @tty: tty | |
392 | * | |
393 | * Flush the line discipline queue (if any) for this tty. If there | |
394 | * is no line discipline active this is a no-op. | |
395 | */ | |
396 | ||
397 | void tty_ldisc_flush(struct tty_struct *tty) | |
398 | { | |
399 | struct tty_ldisc *ld = tty_ldisc_ref(tty); | |
400 | if (ld) { | |
401 | if (ld->ops->flush_buffer) | |
402 | ld->ops->flush_buffer(tty); | |
403 | tty_ldisc_deref(ld); | |
404 | } | |
405 | tty_buffer_flush(tty); | |
406 | } | |
f2c4c65c AC |
407 | EXPORT_SYMBOL_GPL(tty_ldisc_flush); |
408 | ||
01e1abb2 AC |
409 | /** |
410 | * tty_set_termios_ldisc - set ldisc field | |
411 | * @tty: tty structure | |
412 | * @num: line discipline number | |
413 | * | |
414 | * This is probably overkill for real world processors but | |
415 | * they are not on hot paths so a little discipline won't do | |
416 | * any harm. | |
417 | * | |
418 | * Locking: takes termios_mutex | |
419 | */ | |
420 | ||
421 | static void tty_set_termios_ldisc(struct tty_struct *tty, int num) | |
422 | { | |
423 | mutex_lock(&tty->termios_mutex); | |
adc8d746 | 424 | tty->termios.c_line = num; |
01e1abb2 AC |
425 | mutex_unlock(&tty->termios_mutex); |
426 | } | |
427 | ||
c65c9bc3 AC |
428 | /** |
429 | * tty_ldisc_open - open a line discipline | |
430 | * @tty: tty we are opening the ldisc on | |
431 | * @ld: discipline to open | |
432 | * | |
433 | * A helper opening method. Also a convenient debugging and check | |
434 | * point. | |
ec79d605 AB |
435 | * |
436 | * Locking: always called with BTM already held. | |
c65c9bc3 AC |
437 | */ |
438 | ||
439 | static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) | |
440 | { | |
441 | WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); | |
f18f9498 AC |
442 | if (ld->ops->open) { |
443 | int ret; | |
ec79d605 | 444 | /* BTM here locks versus a hangup event */ |
f18f9498 | 445 | ret = ld->ops->open(tty); |
7f90cfc5 JS |
446 | if (ret) |
447 | clear_bit(TTY_LDISC_OPEN, &tty->flags); | |
f18f9498 AC |
448 | return ret; |
449 | } | |
c65c9bc3 AC |
450 | return 0; |
451 | } | |
452 | ||
453 | /** | |
454 | * tty_ldisc_close - close a line discipline | |
455 | * @tty: tty we are opening the ldisc on | |
456 | * @ld: discipline to close | |
457 | * | |
458 | * A helper close method. Also a convenient debugging and check | |
459 | * point. | |
460 | */ | |
461 | ||
462 | static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) | |
463 | { | |
464 | WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); | |
465 | clear_bit(TTY_LDISC_OPEN, &tty->flags); | |
466 | if (ld->ops->close) | |
467 | ld->ops->close(tty); | |
468 | } | |
01e1abb2 AC |
469 | |
470 | /** | |
471 | * tty_ldisc_restore - helper for tty ldisc change | |
472 | * @tty: tty to recover | |
473 | * @old: previous ldisc | |
474 | * | |
475 | * Restore the previous line discipline or N_TTY when a line discipline | |
476 | * change fails due to an open error | |
477 | */ | |
478 | ||
479 | static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) | |
480 | { | |
481 | char buf[64]; | |
c65c9bc3 AC |
482 | struct tty_ldisc *new_ldisc; |
483 | int r; | |
01e1abb2 AC |
484 | |
485 | /* There is an outstanding reference here so this is safe */ | |
36697529 | 486 | old = tty_ldisc_get(tty, old->ops->num); |
c65c9bc3 | 487 | WARN_ON(IS_ERR(old)); |
f4807045 | 488 | tty->ldisc = old; |
01e1abb2 | 489 | tty_set_termios_ldisc(tty, old->ops->num); |
c65c9bc3 AC |
490 | if (tty_ldisc_open(tty, old) < 0) { |
491 | tty_ldisc_put(old); | |
01e1abb2 | 492 | /* This driver is always present */ |
36697529 | 493 | new_ldisc = tty_ldisc_get(tty, N_TTY); |
c65c9bc3 | 494 | if (IS_ERR(new_ldisc)) |
01e1abb2 | 495 | panic("n_tty: get"); |
f4807045 | 496 | tty->ldisc = new_ldisc; |
01e1abb2 | 497 | tty_set_termios_ldisc(tty, N_TTY); |
c65c9bc3 AC |
498 | r = tty_ldisc_open(tty, new_ldisc); |
499 | if (r < 0) | |
500 | panic("Couldn't open N_TTY ldisc for " | |
501 | "%s --- error %d.", | |
502 | tty_name(tty, buf), r); | |
01e1abb2 AC |
503 | } |
504 | } | |
505 | ||
506 | /** | |
507 | * tty_set_ldisc - set line discipline | |
508 | * @tty: the terminal to set | |
509 | * @ldisc: the line discipline | |
510 | * | |
511 | * Set the discipline of a tty line. Must be called from a process | |
c65c9bc3 AC |
512 | * context. The ldisc change logic has to protect itself against any |
513 | * overlapping ldisc change (including on the other end of pty pairs), | |
514 | * the close of one side of a tty/pty pair, and eventually hangup. | |
01e1abb2 AC |
515 | */ |
516 | ||
517 | int tty_set_ldisc(struct tty_struct *tty, int ldisc) | |
518 | { | |
519 | int retval; | |
9fbfa34c | 520 | struct tty_ldisc *old_ldisc, *new_ldisc; |
36697529 | 521 | struct tty_struct *o_tty = tty->link; |
01e1abb2 | 522 | |
36697529 | 523 | new_ldisc = tty_ldisc_get(tty, ldisc); |
c65c9bc3 AC |
524 | if (IS_ERR(new_ldisc)) |
525 | return PTR_ERR(new_ldisc); | |
01e1abb2 | 526 | |
36697529 PH |
527 | retval = tty_ldisc_lock_pair_timeout(tty, o_tty, 5 * HZ); |
528 | if (retval) { | |
529 | tty_ldisc_put(new_ldisc); | |
530 | return retval; | |
531 | } | |
01e1abb2 | 532 | |
c65c9bc3 AC |
533 | /* |
534 | * Check the no-op case | |
535 | */ | |
536 | ||
537 | if (tty->ldisc->ops->num == ldisc) { | |
36697529 | 538 | tty_ldisc_enable_pair(tty, o_tty); |
c65c9bc3 | 539 | tty_ldisc_put(new_ldisc); |
01e1abb2 AC |
540 | return 0; |
541 | } | |
542 | ||
9fbfa34c | 543 | old_ldisc = tty->ldisc; |
89c8d91e | 544 | tty_lock(tty); |
100eeae2 | 545 | |
e97733ca PH |
546 | if (test_bit(TTY_HUPPING, &tty->flags) || |
547 | test_bit(TTY_HUPPED, &tty->flags)) { | |
c65c9bc3 AC |
548 | /* We were raced by the hangup method. It will have stomped |
549 | the ldisc data and closed the ldisc down */ | |
36697529 | 550 | tty_ldisc_enable_pair(tty, o_tty); |
c65c9bc3 | 551 | tty_ldisc_put(new_ldisc); |
89c8d91e | 552 | tty_unlock(tty); |
c65c9bc3 AC |
553 | return -EIO; |
554 | } | |
555 | ||
9fbfa34c PH |
556 | /* Shutdown the old discipline. */ |
557 | tty_ldisc_close(tty, old_ldisc); | |
01e1abb2 AC |
558 | |
559 | /* Now set up the new line discipline. */ | |
f4807045 | 560 | tty->ldisc = new_ldisc; |
01e1abb2 | 561 | tty_set_termios_ldisc(tty, ldisc); |
c65c9bc3 AC |
562 | |
563 | retval = tty_ldisc_open(tty, new_ldisc); | |
01e1abb2 | 564 | if (retval < 0) { |
c65c9bc3 AC |
565 | /* Back to the old one or N_TTY if we can't */ |
566 | tty_ldisc_put(new_ldisc); | |
9fbfa34c | 567 | tty_ldisc_restore(tty, old_ldisc); |
01e1abb2 | 568 | } |
c65c9bc3 | 569 | |
9fbfa34c | 570 | if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) |
01e1abb2 AC |
571 | tty->ops->set_ldisc(tty); |
572 | ||
b0e95858 PH |
573 | /* At this point we hold a reference to the new ldisc and a |
574 | reference to the old ldisc, or we hold two references to | |
575 | the old ldisc (if it was restored as part of error cleanup | |
576 | above). In either case, releasing a single reference from | |
577 | the old ldisc is correct. */ | |
578 | ||
9fbfa34c | 579 | tty_ldisc_put(old_ldisc); |
01e1abb2 AC |
580 | |
581 | /* | |
c65c9bc3 | 582 | * Allow ldisc referencing to occur again |
01e1abb2 | 583 | */ |
36697529 | 584 | tty_ldisc_enable_pair(tty, o_tty); |
01e1abb2 | 585 | |
c65c9bc3 | 586 | /* Restart the work queue in case no characters kick it off. Safe if |
01e1abb2 | 587 | already running */ |
4f98d467 PH |
588 | schedule_work(&tty->port->buf.work); |
589 | if (o_tty) | |
ecbbfd44 | 590 | schedule_work(&o_tty->port->buf.work); |
4f98d467 | 591 | |
89c8d91e | 592 | tty_unlock(tty); |
01e1abb2 AC |
593 | return retval; |
594 | } | |
595 | ||
c65c9bc3 AC |
596 | /** |
597 | * tty_reset_termios - reset terminal state | |
598 | * @tty: tty to reset | |
599 | * | |
600 | * Restore a terminal to the driver default state. | |
601 | */ | |
602 | ||
603 | static void tty_reset_termios(struct tty_struct *tty) | |
604 | { | |
605 | mutex_lock(&tty->termios_mutex); | |
adc8d746 AC |
606 | tty->termios = tty->driver->init_termios; |
607 | tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); | |
608 | tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); | |
c65c9bc3 AC |
609 | mutex_unlock(&tty->termios_mutex); |
610 | } | |
611 | ||
612 | ||
613 | /** | |
614 | * tty_ldisc_reinit - reinitialise the tty ldisc | |
615 | * @tty: tty to reinit | |
638b9648 | 616 | * @ldisc: line discipline to reinitialize |
c65c9bc3 | 617 | * |
638b9648 AC |
618 | * Switch the tty to a line discipline and leave the ldisc |
619 | * state closed | |
c65c9bc3 AC |
620 | */ |
621 | ||
1c95ba1e | 622 | static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) |
c65c9bc3 | 623 | { |
36697529 | 624 | struct tty_ldisc *ld = tty_ldisc_get(tty, ldisc); |
1c95ba1e PR |
625 | |
626 | if (IS_ERR(ld)) | |
627 | return -1; | |
c65c9bc3 AC |
628 | |
629 | tty_ldisc_close(tty, tty->ldisc); | |
630 | tty_ldisc_put(tty->ldisc); | |
c65c9bc3 AC |
631 | /* |
632 | * Switch the line discipline back | |
633 | */ | |
f4807045 | 634 | tty->ldisc = ld; |
638b9648 | 635 | tty_set_termios_ldisc(tty, ldisc); |
1c95ba1e PR |
636 | |
637 | return 0; | |
c65c9bc3 AC |
638 | } |
639 | ||
640 | /** | |
641 | * tty_ldisc_hangup - hangup ldisc reset | |
642 | * @tty: tty being hung up | |
643 | * | |
644 | * Some tty devices reset their termios when they receive a hangup | |
645 | * event. In that situation we must also switch back to N_TTY properly | |
646 | * before we reset the termios data. | |
647 | * | |
648 | * Locking: We can take the ldisc mutex as the rest of the code is | |
649 | * careful to allow for this. | |
650 | * | |
651 | * In the pty pair case this occurs in the close() path of the | |
652 | * tty itself so we must be careful about locking rules. | |
653 | */ | |
654 | ||
655 | void tty_ldisc_hangup(struct tty_struct *tty) | |
656 | { | |
657 | struct tty_ldisc *ld; | |
638b9648 AC |
658 | int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; |
659 | int err = 0; | |
c65c9bc3 | 660 | |
fc575ee6 PH |
661 | tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); |
662 | ||
c65c9bc3 AC |
663 | ld = tty_ldisc_ref(tty); |
664 | if (ld != NULL) { | |
c65c9bc3 AC |
665 | if (ld->ops->flush_buffer) |
666 | ld->ops->flush_buffer(tty); | |
667 | tty_driver_flush_buffer(tty); | |
668 | if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && | |
669 | ld->ops->write_wakeup) | |
670 | ld->ops->write_wakeup(tty); | |
671 | if (ld->ops->hangup) | |
672 | ld->ops->hangup(tty); | |
673 | tty_ldisc_deref(ld); | |
674 | } | |
36697529 | 675 | |
c65c9bc3 AC |
676 | wake_up_interruptible_poll(&tty->write_wait, POLLOUT); |
677 | wake_up_interruptible_poll(&tty->read_wait, POLLIN); | |
36697529 PH |
678 | |
679 | tty_unlock(tty); | |
680 | ||
c65c9bc3 AC |
681 | /* |
682 | * Shutdown the current line discipline, and reset it to | |
638b9648 AC |
683 | * N_TTY if need be. |
684 | * | |
685 | * Avoid racing set_ldisc or tty_ldisc_release | |
c65c9bc3 | 686 | */ |
36697529 PH |
687 | tty_ldisc_lock_pair(tty, tty->link); |
688 | tty_lock(tty); | |
60af22d2 | 689 | |
36697529 | 690 | if (tty->ldisc) { |
c8785241 PH |
691 | |
692 | /* At this point we have a halted ldisc; we want to close it and | |
693 | reopen a new ldisc. We could defer the reopen to the next | |
694 | open but it means auditing a lot of other paths so this is | |
695 | a FIXME */ | |
638b9648 | 696 | if (reset == 0) { |
1c95ba1e | 697 | |
adc8d746 | 698 | if (!tty_ldisc_reinit(tty, tty->termios.c_line)) |
1c95ba1e PR |
699 | err = tty_ldisc_open(tty, tty->ldisc); |
700 | else | |
701 | err = 1; | |
638b9648 AC |
702 | } |
703 | /* If the re-open fails or we reset then go to N_TTY. The | |
704 | N_TTY open cannot fail */ | |
705 | if (reset || err) { | |
1c95ba1e | 706 | BUG_ON(tty_ldisc_reinit(tty, N_TTY)); |
c8d50041 | 707 | WARN_ON(tty_ldisc_open(tty, tty->ldisc)); |
c8d50041 | 708 | } |
c65c9bc3 | 709 | } |
36697529 | 710 | tty_ldisc_enable_pair(tty, tty->link); |
638b9648 AC |
711 | if (reset) |
712 | tty_reset_termios(tty); | |
fc575ee6 PH |
713 | |
714 | tty_ldisc_debug(tty, "re-opened ldisc: %p\n", tty->ldisc); | |
c65c9bc3 | 715 | } |
01e1abb2 AC |
716 | |
717 | /** | |
718 | * tty_ldisc_setup - open line discipline | |
719 | * @tty: tty being shut down | |
720 | * @o_tty: pair tty for pty/tty pairs | |
721 | * | |
722 | * Called during the initial open of a tty/pty pair in order to set up the | |
c65c9bc3 AC |
723 | * line disciplines and bind them to the tty. This has no locking issues |
724 | * as the device isn't yet active. | |
01e1abb2 AC |
725 | */ |
726 | ||
727 | int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) | |
728 | { | |
c65c9bc3 | 729 | struct tty_ldisc *ld = tty->ldisc; |
01e1abb2 AC |
730 | int retval; |
731 | ||
c65c9bc3 AC |
732 | retval = tty_ldisc_open(tty, ld); |
733 | if (retval) | |
734 | return retval; | |
735 | ||
736 | if (o_tty) { | |
737 | retval = tty_ldisc_open(o_tty, o_tty->ldisc); | |
01e1abb2 | 738 | if (retval) { |
c65c9bc3 | 739 | tty_ldisc_close(tty, ld); |
01e1abb2 AC |
740 | return retval; |
741 | } | |
01e1abb2 | 742 | } |
01e1abb2 AC |
743 | return 0; |
744 | } | |
89c8d91e AC |
745 | |
746 | static void tty_ldisc_kill(struct tty_struct *tty) | |
747 | { | |
89c8d91e AC |
748 | /* |
749 | * Now kill off the ldisc | |
750 | */ | |
751 | tty_ldisc_close(tty, tty->ldisc); | |
752 | tty_ldisc_put(tty->ldisc); | |
753 | /* Force an oops if we mess this up */ | |
754 | tty->ldisc = NULL; | |
755 | ||
756 | /* Ensure the next open requests the N_TTY ldisc */ | |
757 | tty_set_termios_ldisc(tty, N_TTY); | |
89c8d91e AC |
758 | } |
759 | ||
01e1abb2 AC |
760 | /** |
761 | * tty_ldisc_release - release line discipline | |
762 | * @tty: tty being shut down | |
763 | * @o_tty: pair tty for pty/tty pairs | |
764 | * | |
852e99d2 AC |
765 | * Called during the final close of a tty/pty pair in order to shut down |
766 | * the line discpline layer. On exit the ldisc assigned is N_TTY and the | |
c65c9bc3 | 767 | * ldisc has not been opened. |
01e1abb2 AC |
768 | */ |
769 | ||
770 | void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) | |
771 | { | |
01e1abb2 | 772 | /* |
a2965b7b PH |
773 | * Shutdown this line discipline. As this is the final close, |
774 | * it does not race with the set_ldisc code path. | |
01e1abb2 | 775 | */ |
01e1abb2 | 776 | |
fc575ee6 PH |
777 | tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); |
778 | ||
36697529 | 779 | tty_ldisc_lock_pair(tty, o_tty); |
852e4a81 | 780 | tty_lock_pair(tty, o_tty); |
36697529 | 781 | |
89c8d91e | 782 | tty_ldisc_kill(tty); |
c65c9bc3 | 783 | if (o_tty) |
89c8d91e | 784 | tty_ldisc_kill(o_tty); |
aef29bc2 | 785 | |
89c8d91e | 786 | tty_unlock_pair(tty, o_tty); |
36697529 PH |
787 | tty_ldisc_unlock_pair(tty, o_tty); |
788 | ||
aef29bc2 AC |
789 | /* And the memory resources remaining (buffers, termios) will be |
790 | disposed of when the kref hits zero */ | |
fc575ee6 PH |
791 | |
792 | tty_ldisc_debug(tty, "ldisc closed\n"); | |
01e1abb2 AC |
793 | } |
794 | ||
795 | /** | |
796 | * tty_ldisc_init - ldisc setup for new tty | |
797 | * @tty: tty being allocated | |
798 | * | |
799 | * Set up the line discipline objects for a newly allocated tty. Note that | |
800 | * the tty structure is not completely set up when this call is made. | |
801 | */ | |
802 | ||
803 | void tty_ldisc_init(struct tty_struct *tty) | |
804 | { | |
36697529 | 805 | struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); |
c65c9bc3 | 806 | if (IS_ERR(ld)) |
01e1abb2 | 807 | panic("n_tty: init_tty"); |
f4807045 | 808 | tty->ldisc = ld; |
01e1abb2 AC |
809 | } |
810 | ||
6716671d JS |
811 | /** |
812 | * tty_ldisc_init - ldisc cleanup for new tty | |
813 | * @tty: tty that was allocated recently | |
814 | * | |
815 | * The tty structure must not becompletely set up (tty_ldisc_setup) when | |
816 | * this call is made. | |
817 | */ | |
818 | void tty_ldisc_deinit(struct tty_struct *tty) | |
819 | { | |
ebc9baed | 820 | tty_ldisc_put(tty->ldisc); |
f4807045 | 821 | tty->ldisc = NULL; |
6716671d JS |
822 | } |
823 | ||
01e1abb2 AC |
824 | void tty_ldisc_begin(void) |
825 | { | |
826 | /* Setup the default TTY line discipline. */ | |
827 | (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); | |
828 | } |