Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 1 | #include <linux/types.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 2 | #include <linux/errno.h> |
Jiri Slaby | 8b3ffa1 | 2011-11-16 16:27:10 +0100 | [diff] [blame] | 3 | #include <linux/kmod.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 4 | #include <linux/sched.h> |
| 5 | #include <linux/interrupt.h> |
| 6 | #include <linux/tty.h> |
| 7 | #include <linux/tty_driver.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 8 | #include <linux/file.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 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> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 14 | #include <linux/module.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 15 | #include <linux/device.h> |
| 16 | #include <linux/wait.h> |
| 17 | #include <linux/bitops.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 18 | #include <linux/seq_file.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 19 | #include <linux/uaccess.h> |
Jiri Slaby | 0c73c08 | 2011-11-16 16:27:09 +0100 | [diff] [blame] | 20 | #include <linux/ratelimit.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 21 | |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 22 | #undef LDISC_DEBUG_HANGUP |
| 23 | |
| 24 | #ifdef LDISC_DEBUG_HANGUP |
Peter Hurley | 0a6adc1 | 2015-07-12 22:49:10 -0400 | [diff] [blame] | 25 | #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 26 | #else |
| 27 | #define tty_ldisc_debug(tty, f, args...) |
| 28 | #endif |
| 29 | |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 30 | /* lockdep nested classes for tty->ldisc_sem */ |
| 31 | enum { |
| 32 | LDISC_SEM_NORMAL, |
| 33 | LDISC_SEM_OTHER, |
| 34 | }; |
| 35 | |
| 36 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 37 | /* |
| 38 | * This guards the refcounted line discipline lists. The lock |
| 39 | * must be taken with irqs off because there are hangup path |
| 40 | * callers who will do ldisc lookups and cannot sleep. |
| 41 | */ |
| 42 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 43 | static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 44 | /* Line disc dispatch table */ |
| 45 | static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; |
| 46 | |
| 47 | /** |
| 48 | * tty_register_ldisc - install a line discipline |
| 49 | * @disc: ldisc number |
| 50 | * @new_ldisc: pointer to the ldisc object |
| 51 | * |
| 52 | * Installs a new line discipline into the kernel. The discipline |
| 53 | * is set up as unreferenced and then made available to the kernel |
| 54 | * from this point onwards. |
| 55 | * |
| 56 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 57 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 58 | */ |
| 59 | |
| 60 | int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) |
| 61 | { |
| 62 | unsigned long flags; |
| 63 | int ret = 0; |
| 64 | |
| 65 | if (disc < N_TTY || disc >= NR_LDISCS) |
| 66 | return -EINVAL; |
| 67 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 68 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 69 | tty_ldiscs[disc] = new_ldisc; |
| 70 | new_ldisc->num = disc; |
| 71 | new_ldisc->refcount = 0; |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 72 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 73 | |
| 74 | return ret; |
| 75 | } |
| 76 | EXPORT_SYMBOL(tty_register_ldisc); |
| 77 | |
| 78 | /** |
| 79 | * tty_unregister_ldisc - unload a line discipline |
| 80 | * @disc: ldisc number |
| 81 | * @new_ldisc: pointer to the ldisc object |
| 82 | * |
| 83 | * Remove a line discipline from the kernel providing it is not |
| 84 | * currently in use. |
| 85 | * |
| 86 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 87 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 88 | */ |
| 89 | |
| 90 | int tty_unregister_ldisc(int disc) |
| 91 | { |
| 92 | unsigned long flags; |
| 93 | int ret = 0; |
| 94 | |
| 95 | if (disc < N_TTY || disc >= NR_LDISCS) |
| 96 | return -EINVAL; |
| 97 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 98 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 99 | if (tty_ldiscs[disc]->refcount) |
| 100 | ret = -EBUSY; |
| 101 | else |
| 102 | tty_ldiscs[disc] = NULL; |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 103 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 104 | |
| 105 | return ret; |
| 106 | } |
| 107 | EXPORT_SYMBOL(tty_unregister_ldisc); |
| 108 | |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 109 | static struct tty_ldisc_ops *get_ldops(int disc) |
| 110 | { |
| 111 | unsigned long flags; |
| 112 | struct tty_ldisc_ops *ldops, *ret; |
| 113 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 114 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 115 | ret = ERR_PTR(-EINVAL); |
| 116 | ldops = tty_ldiscs[disc]; |
| 117 | if (ldops) { |
| 118 | ret = ERR_PTR(-EAGAIN); |
| 119 | if (try_module_get(ldops->owner)) { |
| 120 | ldops->refcount++; |
| 121 | ret = ldops; |
| 122 | } |
| 123 | } |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 124 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 125 | return ret; |
| 126 | } |
| 127 | |
| 128 | static void put_ldops(struct tty_ldisc_ops *ldops) |
| 129 | { |
| 130 | unsigned long flags; |
| 131 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 132 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 133 | ldops->refcount--; |
| 134 | module_put(ldops->owner); |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 135 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 136 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 137 | |
| 138 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 139 | * tty_ldisc_get - take a reference to an ldisc |
| 140 | * @disc: ldisc number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 141 | * |
| 142 | * Takes a reference to a line discipline. Deals with refcounts and |
Peter Hurley | c0cc1c5 | 2016-01-10 22:40:59 -0800 | [diff] [blame] | 143 | * module locking counts. |
| 144 | * |
| 145 | * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or |
| 146 | * if the discipline is not registered |
| 147 | * -EAGAIN if request_module() failed to load or register the |
| 148 | * the discipline |
| 149 | * -ENOMEM if allocation failure |
| 150 | * |
| 151 | * Otherwise, returns a pointer to the discipline and bumps the |
| 152 | * ref count |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 153 | * |
| 154 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 155 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 156 | */ |
| 157 | |
Greg Kroah-Hartman | 9b7984e | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 158 | #if defined(CONFIG_LDISC_AUTOLOAD) |
| 159 | #define INITIAL_AUTOLOAD_STATE 1 |
| 160 | #else |
| 161 | #define INITIAL_AUTOLOAD_STATE 0 |
| 162 | #endif |
| 163 | static int tty_ldisc_autoload = INITIAL_AUTOLOAD_STATE; |
| 164 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 165 | static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 166 | { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 167 | struct tty_ldisc *ld; |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 168 | struct tty_ldisc_ops *ldops; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 169 | |
| 170 | if (disc < N_TTY || disc >= NR_LDISCS) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 171 | return ERR_PTR(-EINVAL); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 172 | |
| 173 | /* |
| 174 | * Get the ldisc ops - we may need to request them to be loaded |
| 175 | * dynamically and try again. |
| 176 | */ |
| 177 | ldops = get_ldops(disc); |
| 178 | if (IS_ERR(ldops)) { |
Greg Kroah-Hartman | 9b7984e | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 179 | if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload) |
| 180 | return ERR_PTR(-EPERM); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 181 | request_module("tty-ldisc-%d", disc); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 182 | ldops = get_ldops(disc); |
| 183 | if (IS_ERR(ldops)) |
| 184 | return ERR_CAST(ldops); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 185 | } |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 186 | |
Tetsuo Handa | ad30f05 | 2018-04-25 20:12:31 +0900 | [diff] [blame] | 187 | /* |
| 188 | * There is no way to handle allocation failure of only 16 bytes. |
| 189 | * Let's simplify error handling and save more memory. |
| 190 | */ |
| 191 | ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 192 | ld->ops = ldops; |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 193 | ld->tty = tty; |
Ivo Sieben | 1541f84 | 2012-05-03 14:37:43 +0200 | [diff] [blame] | 194 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 195 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 196 | } |
| 197 | |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 198 | /** |
| 199 | * tty_ldisc_put - release the ldisc |
| 200 | * |
| 201 | * Complement of tty_ldisc_get(). |
| 202 | */ |
Denys Vlasenko | cb128f6 | 2015-10-27 17:40:02 +0100 | [diff] [blame] | 203 | static void tty_ldisc_put(struct tty_ldisc *ld) |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 204 | { |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 205 | if (WARN_ON_ONCE(!ld)) |
| 206 | return; |
| 207 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 208 | put_ldops(ld->ops); |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 209 | kfree(ld); |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 210 | } |
| 211 | |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 212 | static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 213 | { |
| 214 | return (*pos < NR_LDISCS) ? pos : NULL; |
| 215 | } |
| 216 | |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 217 | static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 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; |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 230 | struct tty_ldisc_ops *ldops; |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 231 | |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 232 | ldops = get_ldops(i); |
| 233 | if (IS_ERR(ldops)) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 234 | return 0; |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 235 | seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); |
| 236 | put_ldops(ldops); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 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 | |
| 260 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 261 | * tty_ldisc_ref_wait - wait for the tty ldisc |
| 262 | * @tty: tty device |
| 263 | * |
| 264 | * Dereference the line discipline for the terminal and take a |
| 265 | * reference to it. If the line discipline is in flux then |
| 266 | * wait patiently until it changes. |
| 267 | * |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 268 | * Returns: NULL if the tty has been hungup and not re-opened with |
| 269 | * a new file descriptor, otherwise valid ldisc reference |
| 270 | * |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 271 | * Note: Must not be called from an IRQ/timer context. The caller |
| 272 | * must also be careful not to hold other locks that will deadlock |
| 273 | * against a discipline change, such as an existing ldisc reference |
| 274 | * (which we check for) |
| 275 | * |
Peter Hurley | e55afd1 | 2016-01-10 22:41:01 -0800 | [diff] [blame] | 276 | * Note: a file_operations routine (read/poll/write) should use this |
| 277 | * function to wait for any ldisc lifetime events to finish. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 278 | */ |
| 279 | |
| 280 | struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) |
| 281 | { |
Dmitry Vyukov | 2a47e7d | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 282 | struct tty_ldisc *ld; |
| 283 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 284 | ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); |
Dmitry Vyukov | 2a47e7d | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 285 | ld = tty->ldisc; |
| 286 | if (!ld) |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 287 | ldsem_up_read(&tty->ldisc_sem); |
Dmitry Vyukov | 2a47e7d | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 288 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 289 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 290 | EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); |
| 291 | |
| 292 | /** |
| 293 | * tty_ldisc_ref - get the tty ldisc |
| 294 | * @tty: tty device |
| 295 | * |
| 296 | * Dereference the line discipline for the terminal and take a |
| 297 | * reference to it. If the line discipline is in flux then |
| 298 | * return NULL. Can be called from IRQ and timer functions. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 299 | */ |
| 300 | |
| 301 | struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) |
| 302 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 303 | struct tty_ldisc *ld = NULL; |
| 304 | |
| 305 | if (ldsem_down_read_trylock(&tty->ldisc_sem)) { |
| 306 | ld = tty->ldisc; |
| 307 | if (!ld) |
| 308 | ldsem_up_read(&tty->ldisc_sem); |
| 309 | } |
| 310 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 311 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 312 | EXPORT_SYMBOL_GPL(tty_ldisc_ref); |
| 313 | |
| 314 | /** |
| 315 | * tty_ldisc_deref - free a tty ldisc reference |
| 316 | * @ld: reference to free up |
| 317 | * |
| 318 | * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May |
| 319 | * be called in IRQ context. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 320 | */ |
| 321 | |
| 322 | void tty_ldisc_deref(struct tty_ldisc *ld) |
| 323 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 324 | ldsem_up_read(&ld->tty->ldisc_sem); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 325 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 326 | EXPORT_SYMBOL_GPL(tty_ldisc_deref); |
| 327 | |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 328 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 329 | static inline int |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 330 | __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 331 | { |
| 332 | return ldsem_down_write(&tty->ldisc_sem, timeout); |
| 333 | } |
| 334 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 335 | static inline int |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 336 | __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 337 | { |
| 338 | return ldsem_down_write_nested(&tty->ldisc_sem, |
| 339 | LDISC_SEM_OTHER, timeout); |
| 340 | } |
| 341 | |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 342 | static inline void __tty_ldisc_unlock(struct tty_struct *tty) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 343 | { |
Guillaume Gomez | 52772ea | 2015-10-04 21:19:18 +0200 | [diff] [blame] | 344 | ldsem_up_write(&tty->ldisc_sem); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 345 | } |
| 346 | |
Gaurav Kohli | 55eaecf | 2018-01-23 13:16:34 +0530 | [diff] [blame] | 347 | int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 348 | { |
| 349 | int ret; |
| 350 | |
| 351 | ret = __tty_ldisc_lock(tty, timeout); |
| 352 | if (!ret) |
| 353 | return -EBUSY; |
| 354 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
| 355 | return 0; |
| 356 | } |
| 357 | |
Gaurav Kohli | 55eaecf | 2018-01-23 13:16:34 +0530 | [diff] [blame] | 358 | void tty_ldisc_unlock(struct tty_struct *tty) |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 359 | { |
| 360 | clear_bit(TTY_LDISC_HALTED, &tty->flags); |
| 361 | __tty_ldisc_unlock(tty); |
| 362 | } |
| 363 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 364 | static int |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 365 | tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, |
| 366 | unsigned long timeout) |
| 367 | { |
| 368 | int ret; |
| 369 | |
| 370 | if (tty < tty2) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 371 | ret = __tty_ldisc_lock(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 372 | if (ret) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 373 | ret = __tty_ldisc_lock_nested(tty2, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 374 | if (!ret) |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 375 | __tty_ldisc_unlock(tty); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 376 | } |
| 377 | } else { |
| 378 | /* if this is possible, it has lots of implications */ |
| 379 | WARN_ON_ONCE(tty == tty2); |
| 380 | if (tty2 && tty != tty2) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 381 | ret = __tty_ldisc_lock(tty2, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 382 | if (ret) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 383 | ret = __tty_ldisc_lock_nested(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 384 | if (!ret) |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 385 | __tty_ldisc_unlock(tty2); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 386 | } |
| 387 | } else |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 388 | ret = __tty_ldisc_lock(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 389 | } |
| 390 | |
| 391 | if (!ret) |
| 392 | return -EBUSY; |
| 393 | |
| 394 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
| 395 | if (tty2) |
| 396 | set_bit(TTY_LDISC_HALTED, &tty2->flags); |
| 397 | return 0; |
| 398 | } |
| 399 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 400 | static void tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 401 | { |
| 402 | tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); |
| 403 | } |
| 404 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 405 | static void tty_ldisc_unlock_pair(struct tty_struct *tty, |
| 406 | struct tty_struct *tty2) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 407 | { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 408 | __tty_ldisc_unlock(tty); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 409 | if (tty2) |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 410 | __tty_ldisc_unlock(tty2); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 411 | } |
| 412 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 413 | /** |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 414 | * tty_ldisc_flush - flush line discipline queue |
| 415 | * @tty: tty |
| 416 | * |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 417 | * Flush the line discipline queue (if any) and the tty flip buffers |
| 418 | * for this tty. |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 419 | */ |
| 420 | |
| 421 | void tty_ldisc_flush(struct tty_struct *tty) |
| 422 | { |
| 423 | struct tty_ldisc *ld = tty_ldisc_ref(tty); |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 424 | |
| 425 | tty_buffer_flush(tty, ld); |
| 426 | if (ld) |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 427 | tty_ldisc_deref(ld); |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 428 | } |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 429 | EXPORT_SYMBOL_GPL(tty_ldisc_flush); |
| 430 | |
| 431 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 432 | * tty_set_termios_ldisc - set ldisc field |
| 433 | * @tty: tty structure |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 434 | * @disc: line discipline number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 435 | * |
| 436 | * This is probably overkill for real world processors but |
| 437 | * they are not on hot paths so a little discipline won't do |
| 438 | * any harm. |
| 439 | * |
Peter Hurley | dd42bf1 | 2015-11-27 14:30:21 -0500 | [diff] [blame] | 440 | * The line discipline-related tty_struct fields are reset to |
| 441 | * prevent the ldisc driver from re-using stale information for |
| 442 | * the new ldisc instance. |
| 443 | * |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 444 | * Locking: takes termios_rwsem |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 445 | */ |
| 446 | |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 447 | static void tty_set_termios_ldisc(struct tty_struct *tty, int disc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 448 | { |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 449 | down_write(&tty->termios_rwsem); |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 450 | tty->termios.c_line = disc; |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 451 | up_write(&tty->termios_rwsem); |
Peter Hurley | dd42bf1 | 2015-11-27 14:30:21 -0500 | [diff] [blame] | 452 | |
| 453 | tty->disc_data = NULL; |
| 454 | tty->receive_room = 0; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 455 | } |
| 456 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 457 | /** |
| 458 | * tty_ldisc_open - open a line discipline |
| 459 | * @tty: tty we are opening the ldisc on |
| 460 | * @ld: discipline to open |
| 461 | * |
| 462 | * A helper opening method. Also a convenient debugging and check |
| 463 | * point. |
Arnd Bergmann | ec79d60 | 2010-06-01 22:53:01 +0200 | [diff] [blame] | 464 | * |
| 465 | * Locking: always called with BTM already held. |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 466 | */ |
| 467 | |
| 468 | static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) |
| 469 | { |
| 470 | WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 471 | if (ld->ops->open) { |
| 472 | int ret; |
Arnd Bergmann | ec79d60 | 2010-06-01 22:53:01 +0200 | [diff] [blame] | 473 | /* BTM here locks versus a hangup event */ |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 474 | ret = ld->ops->open(tty); |
Jiri Slaby | 7f90cfc | 2010-11-25 00:27:54 +0100 | [diff] [blame] | 475 | if (ret) |
| 476 | clear_bit(TTY_LDISC_OPEN, &tty->flags); |
Peter Hurley | fb6edc9 | 2015-07-12 22:49:12 -0400 | [diff] [blame] | 477 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 478 | tty_ldisc_debug(tty, "%p: opened\n", ld); |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 479 | return ret; |
| 480 | } |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 481 | return 0; |
| 482 | } |
| 483 | |
| 484 | /** |
| 485 | * tty_ldisc_close - close a line discipline |
| 486 | * @tty: tty we are opening the ldisc on |
| 487 | * @ld: discipline to close |
| 488 | * |
| 489 | * A helper close method. Also a convenient debugging and check |
| 490 | * point. |
| 491 | */ |
| 492 | |
| 493 | static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) |
| 494 | { |
| 495 | WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); |
| 496 | clear_bit(TTY_LDISC_OPEN, &tty->flags); |
| 497 | if (ld->ops->close) |
| 498 | ld->ops->close(tty); |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 499 | tty_ldisc_debug(tty, "%p: closed\n", ld); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 500 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 501 | |
| 502 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 503 | * tty_set_ldisc - set line discipline |
| 504 | * @tty: the terminal to set |
| 505 | * @ldisc: the line discipline |
| 506 | * |
| 507 | * Set the discipline of a tty line. Must be called from a process |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 508 | * context. The ldisc change logic has to protect itself against any |
| 509 | * overlapping ldisc change (including on the other end of pty pairs), |
| 510 | * the close of one side of a tty/pty pair, and eventually hangup. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 511 | */ |
| 512 | |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 513 | int tty_set_ldisc(struct tty_struct *tty, int disc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 514 | { |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 515 | int retval, old_disc; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 516 | |
Peter Hurley | c8483bc | 2014-11-05 12:12:45 -0500 | [diff] [blame] | 517 | tty_lock(tty); |
Peter Hurley | 276a661 | 2014-11-05 12:13:08 -0500 | [diff] [blame] | 518 | retval = tty_ldisc_lock(tty, 5 * HZ); |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 519 | if (retval) |
| 520 | goto err; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 521 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 522 | if (!tty->ldisc) { |
| 523 | retval = -EIO; |
| 524 | goto out; |
| 525 | } |
| 526 | |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 527 | /* Check the no-op case */ |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 528 | old_disc = tty->ldisc->ops->num; |
| 529 | if (old_disc == disc) |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 530 | goto out; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 531 | |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 532 | if (test_bit(TTY_HUPPED, &tty->flags)) { |
| 533 | /* We were raced by hangup */ |
| 534 | retval = -EIO; |
| 535 | goto out; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 536 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 537 | |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 538 | retval = tty_ldisc_reinit(tty, disc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 539 | if (retval < 0) { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 540 | /* Back to the old one or N_TTY if we can't */ |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 541 | if (tty_ldisc_reinit(tty, old_disc) < 0) { |
| 542 | pr_err("tty: TIOCSETD failed, reinitializing N_TTY\n"); |
| 543 | if (tty_ldisc_reinit(tty, N_TTY) < 0) { |
| 544 | /* At this point we have tty->ldisc == NULL. */ |
| 545 | pr_err("tty: reinitializing N_TTY failed\n"); |
| 546 | } |
| 547 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 548 | } |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 549 | |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 550 | if (tty->ldisc && tty->ldisc->ops->num != old_disc && |
| 551 | tty->ops->set_ldisc) { |
Peter Hurley | 9191aaa | 2014-11-05 13:11:41 -0500 | [diff] [blame] | 552 | down_read(&tty->termios_rwsem); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 553 | tty->ops->set_ldisc(tty); |
Peter Hurley | 9191aaa | 2014-11-05 13:11:41 -0500 | [diff] [blame] | 554 | up_read(&tty->termios_rwsem); |
| 555 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 556 | |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 557 | out: |
Peter Hurley | 276a661 | 2014-11-05 12:13:08 -0500 | [diff] [blame] | 558 | tty_ldisc_unlock(tty); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 559 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 560 | /* Restart the work queue in case no characters kick it off. Safe if |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 561 | already running */ |
Peter Hurley | 17a6921 | 2015-11-08 07:53:06 -0500 | [diff] [blame] | 562 | tty_buffer_restart_work(tty->port); |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 563 | err: |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 564 | tty_unlock(tty); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 565 | return retval; |
| 566 | } |
| 567 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 568 | /** |
Peter Hurley | 6ffeb4b | 2016-01-10 22:41:03 -0800 | [diff] [blame] | 569 | * tty_ldisc_kill - teardown ldisc |
| 570 | * @tty: tty being released |
| 571 | * |
| 572 | * Perform final close of the ldisc and reset tty->ldisc |
| 573 | */ |
| 574 | static void tty_ldisc_kill(struct tty_struct *tty) |
| 575 | { |
| 576 | if (!tty->ldisc) |
| 577 | return; |
| 578 | /* |
| 579 | * Now kill off the ldisc |
| 580 | */ |
| 581 | tty_ldisc_close(tty, tty->ldisc); |
| 582 | tty_ldisc_put(tty->ldisc); |
| 583 | /* Force an oops if we mess this up */ |
| 584 | tty->ldisc = NULL; |
| 585 | } |
| 586 | |
| 587 | /** |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 588 | * tty_reset_termios - reset terminal state |
| 589 | * @tty: tty to reset |
| 590 | * |
| 591 | * Restore a terminal to the driver default state. |
| 592 | */ |
| 593 | |
| 594 | static void tty_reset_termios(struct tty_struct *tty) |
| 595 | { |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 596 | down_write(&tty->termios_rwsem); |
Alan Cox | adc8d74 | 2012-07-14 15:31:47 +0100 | [diff] [blame] | 597 | tty->termios = tty->driver->init_termios; |
| 598 | tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); |
| 599 | tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 600 | up_write(&tty->termios_rwsem); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 601 | } |
| 602 | |
| 603 | |
| 604 | /** |
| 605 | * tty_ldisc_reinit - reinitialise the tty ldisc |
| 606 | * @tty: tty to reinit |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 607 | * @disc: line discipline to reinitialize |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 608 | * |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 609 | * Completely reinitialize the line discipline state, by closing the |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 610 | * current instance, if there is one, and opening a new instance. If |
| 611 | * an error occurs opening the new non-N_TTY instance, the instance |
| 612 | * is dropped and tty->ldisc reset to NULL. The caller can then retry |
| 613 | * with N_TTY instead. |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 614 | * |
| 615 | * Returns 0 if successful, otherwise error code < 0 |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 616 | */ |
| 617 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 618 | int tty_ldisc_reinit(struct tty_struct *tty, int disc) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 619 | { |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 620 | struct tty_ldisc *ld; |
| 621 | int retval; |
Philippe Rétornaz | 1c95ba1 | 2010-10-27 17:13:21 +0200 | [diff] [blame] | 622 | |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 623 | ld = tty_ldisc_get(tty, disc); |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 624 | if (IS_ERR(ld)) |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 625 | return PTR_ERR(ld); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 626 | |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 627 | if (tty->ldisc) { |
| 628 | tty_ldisc_close(tty, tty->ldisc); |
| 629 | tty_ldisc_put(tty->ldisc); |
| 630 | } |
| 631 | |
| 632 | /* switch the line discipline */ |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 633 | tty->ldisc = ld; |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 634 | tty_set_termios_ldisc(tty, disc); |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 635 | retval = tty_ldisc_open(tty, tty->ldisc); |
| 636 | if (retval) { |
Dmitry Vyukov | 70f450f | 2017-03-04 14:55:19 +0100 | [diff] [blame] | 637 | tty_ldisc_put(tty->ldisc); |
| 638 | tty->ldisc = NULL; |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 639 | } |
| 640 | return retval; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 641 | } |
| 642 | |
| 643 | /** |
| 644 | * tty_ldisc_hangup - hangup ldisc reset |
| 645 | * @tty: tty being hung up |
| 646 | * |
| 647 | * Some tty devices reset their termios when they receive a hangup |
| 648 | * event. In that situation we must also switch back to N_TTY properly |
| 649 | * before we reset the termios data. |
| 650 | * |
| 651 | * Locking: We can take the ldisc mutex as the rest of the code is |
| 652 | * careful to allow for this. |
| 653 | * |
| 654 | * In the pty pair case this occurs in the close() path of the |
| 655 | * tty itself so we must be careful about locking rules. |
| 656 | */ |
| 657 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 658 | void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 659 | { |
| 660 | struct tty_ldisc *ld; |
| 661 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 662 | tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc); |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 663 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 664 | ld = tty_ldisc_ref(tty); |
| 665 | if (ld != NULL) { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 666 | if (ld->ops->flush_buffer) |
| 667 | ld->ops->flush_buffer(tty); |
| 668 | tty_driver_flush_buffer(tty); |
| 669 | if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && |
| 670 | ld->ops->write_wakeup) |
| 671 | ld->ops->write_wakeup(tty); |
| 672 | if (ld->ops->hangup) |
| 673 | ld->ops->hangup(tty); |
| 674 | tty_ldisc_deref(ld); |
| 675 | } |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 676 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 677 | wake_up_interruptible_poll(&tty->write_wait, POLLOUT); |
| 678 | wake_up_interruptible_poll(&tty->read_wait, POLLIN); |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 679 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 680 | /* |
| 681 | * Shutdown the current line discipline, and reset it to |
Alan Cox | 638b964 | 2010-02-08 10:09:26 +0000 | [diff] [blame] | 682 | * N_TTY if need be. |
| 683 | * |
| 684 | * Avoid racing set_ldisc or tty_ldisc_release |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 685 | */ |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 686 | tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); |
Arnd Bergmann | 60af22d | 2010-06-01 22:53:06 +0200 | [diff] [blame] | 687 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 688 | if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) |
Alan Cox | 638b964 | 2010-02-08 10:09:26 +0000 | [diff] [blame] | 689 | tty_reset_termios(tty); |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 690 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 691 | if (tty->ldisc) { |
| 692 | if (reinit) { |
| 693 | if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0) |
| 694 | tty_ldisc_reinit(tty, N_TTY); |
| 695 | } else |
| 696 | tty_ldisc_kill(tty); |
| 697 | } |
| 698 | tty_ldisc_unlock(tty); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 699 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 700 | |
| 701 | /** |
| 702 | * tty_ldisc_setup - open line discipline |
| 703 | * @tty: tty being shut down |
| 704 | * @o_tty: pair tty for pty/tty pairs |
| 705 | * |
| 706 | * Called during the initial open of a tty/pty pair in order to set up the |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 707 | * line disciplines and bind them to the tty. This has no locking issues |
| 708 | * as the device isn't yet active. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 709 | */ |
| 710 | |
| 711 | int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) |
| 712 | { |
Peter Hurley | 9de2a7c | 2016-01-10 22:41:08 -0800 | [diff] [blame] | 713 | int retval = tty_ldisc_open(tty, tty->ldisc); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 714 | if (retval) |
| 715 | return retval; |
| 716 | |
| 717 | if (o_tty) { |
| 718 | retval = tty_ldisc_open(o_tty, o_tty->ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 719 | if (retval) { |
Peter Hurley | 9de2a7c | 2016-01-10 22:41:08 -0800 | [diff] [blame] | 720 | tty_ldisc_close(tty, tty->ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 721 | return retval; |
| 722 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 723 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 724 | return 0; |
| 725 | } |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 726 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 727 | /** |
| 728 | * tty_ldisc_release - release line discipline |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 729 | * @tty: tty being shut down (or one end of pty pair) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 730 | * |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 731 | * Called during the final close of a tty or a pty pair in order to shut |
Peter Hurley | 5b6e683 | 2016-01-10 22:41:00 -0800 | [diff] [blame] | 732 | * down the line discpline layer. On exit, each tty's ldisc is NULL. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 733 | */ |
| 734 | |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 735 | void tty_ldisc_release(struct tty_struct *tty) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 736 | { |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 737 | struct tty_struct *o_tty = tty->link; |
| 738 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 739 | /* |
Peter Hurley | a2965b7 | 2013-03-11 16:44:35 -0400 | [diff] [blame] | 740 | * Shutdown this line discipline. As this is the final close, |
| 741 | * it does not race with the set_ldisc code path. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 742 | */ |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 743 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 744 | tty_ldisc_lock_pair(tty, o_tty); |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 745 | tty_ldisc_kill(tty); |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 746 | if (o_tty) |
| 747 | tty_ldisc_kill(o_tty); |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 748 | tty_ldisc_unlock_pair(tty, o_tty); |
| 749 | |
Alan Cox | aef29bc | 2009-06-29 15:21:47 +0100 | [diff] [blame] | 750 | /* And the memory resources remaining (buffers, termios) will be |
| 751 | disposed of when the kref hits zero */ |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 752 | |
Peter Hurley | fb6edc9 | 2015-07-12 22:49:12 -0400 | [diff] [blame] | 753 | tty_ldisc_debug(tty, "released\n"); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 754 | } |
| 755 | |
| 756 | /** |
| 757 | * tty_ldisc_init - ldisc setup for new tty |
| 758 | * @tty: tty being allocated |
| 759 | * |
| 760 | * Set up the line discipline objects for a newly allocated tty. Note that |
| 761 | * the tty structure is not completely set up when this call is made. |
| 762 | */ |
| 763 | |
Tetsuo Handa | 6a506d4 | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 764 | int tty_ldisc_init(struct tty_struct *tty) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 765 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 766 | struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 767 | if (IS_ERR(ld)) |
Tetsuo Handa | 6a506d4 | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 768 | return PTR_ERR(ld); |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 769 | tty->ldisc = ld; |
Tetsuo Handa | 6a506d4 | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 770 | return 0; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 771 | } |
| 772 | |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 773 | /** |
Peter Hurley | c8b710b | 2016-01-09 21:13:46 -0800 | [diff] [blame] | 774 | * tty_ldisc_deinit - ldisc cleanup for new tty |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 775 | * @tty: tty that was allocated recently |
| 776 | * |
| 777 | * The tty structure must not becompletely set up (tty_ldisc_setup) when |
| 778 | * this call is made. |
| 779 | */ |
| 780 | void tty_ldisc_deinit(struct tty_struct *tty) |
| 781 | { |
Peter Hurley | c8b710b | 2016-01-09 21:13:46 -0800 | [diff] [blame] | 782 | if (tty->ldisc) |
| 783 | tty_ldisc_put(tty->ldisc); |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 784 | tty->ldisc = NULL; |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 785 | } |
Greg Kroah-Hartman | 9b7984e | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 786 | |
| 787 | static int zero; |
| 788 | static int one = 1; |
| 789 | static struct ctl_table tty_table[] = { |
| 790 | { |
| 791 | .procname = "ldisc_autoload", |
| 792 | .data = &tty_ldisc_autoload, |
| 793 | .maxlen = sizeof(tty_ldisc_autoload), |
| 794 | .mode = 0644, |
| 795 | .proc_handler = proc_dointvec, |
| 796 | .extra1 = &zero, |
| 797 | .extra2 = &one, |
| 798 | }, |
| 799 | { } |
| 800 | }; |
| 801 | |
| 802 | static struct ctl_table tty_dir_table[] = { |
| 803 | { |
| 804 | .procname = "tty", |
| 805 | .mode = 0555, |
| 806 | .child = tty_table, |
| 807 | }, |
| 808 | { } |
| 809 | }; |
| 810 | |
| 811 | static struct ctl_table tty_root_table[] = { |
| 812 | { |
| 813 | .procname = "dev", |
| 814 | .mode = 0555, |
| 815 | .child = tty_dir_table, |
| 816 | }, |
| 817 | { } |
| 818 | }; |
| 819 | |
| 820 | void tty_sysctl_init(void) |
| 821 | { |
| 822 | register_sysctl_table(tty_root_table); |
| 823 | } |