Greg Kroah-Hartman | e3b3d0f | 2017-11-06 18:11:51 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 2 | #include <linux/types.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 3 | #include <linux/errno.h> |
Jiri Slaby | 8b3ffa1 | 2011-11-16 16:27:10 +0100 | [diff] [blame] | 4 | #include <linux/kmod.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 5 | #include <linux/sched.h> |
| 6 | #include <linux/interrupt.h> |
| 7 | #include <linux/tty.h> |
| 8 | #include <linux/tty_driver.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 9 | #include <linux/file.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 10 | #include <linux/mm.h> |
| 11 | #include <linux/string.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/poll.h> |
| 14 | #include <linux/proc_fs.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 15 | #include <linux/module.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 16 | #include <linux/device.h> |
| 17 | #include <linux/wait.h> |
| 18 | #include <linux/bitops.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 19 | #include <linux/seq_file.h> |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 20 | #include <linux/uaccess.h> |
Jiri Slaby | 0c73c08 | 2011-11-16 16:27:09 +0100 | [diff] [blame] | 21 | #include <linux/ratelimit.h> |
Greg Kroah-Hartman | 98602c0 | 2021-04-08 14:51:22 +0200 | [diff] [blame] | 22 | #include "tty.h" |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 23 | |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 24 | #undef LDISC_DEBUG_HANGUP |
| 25 | |
| 26 | #ifdef LDISC_DEBUG_HANGUP |
Peter Hurley | 0a6adc1 | 2015-07-12 22:49:10 -0400 | [diff] [blame] | 27 | #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 28 | #else |
| 29 | #define tty_ldisc_debug(tty, f, args...) |
| 30 | #endif |
| 31 | |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 32 | /* lockdep nested classes for tty->ldisc_sem */ |
| 33 | enum { |
| 34 | LDISC_SEM_NORMAL, |
| 35 | LDISC_SEM_OTHER, |
| 36 | }; |
| 37 | |
| 38 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 39 | /* |
| 40 | * This guards the refcounted line discipline lists. The lock |
| 41 | * must be taken with irqs off because there are hangup path |
| 42 | * callers who will do ldisc lookups and cannot sleep. |
| 43 | */ |
| 44 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 45 | static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 46 | /* Line disc dispatch table */ |
| 47 | static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; |
| 48 | |
| 49 | /** |
| 50 | * tty_register_ldisc - install a line discipline |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 51 | * @new_ldisc: pointer to the ldisc object |
| 52 | * |
| 53 | * Installs a new line discipline into the kernel. The discipline |
| 54 | * is set up as unreferenced and then made available to the kernel |
| 55 | * from this point onwards. |
| 56 | * |
| 57 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 58 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 59 | */ |
| 60 | |
Jiri Slaby | fbadf70a | 2021-05-05 11:19:07 +0200 | [diff] [blame] | 61 | int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 62 | { |
| 63 | unsigned long flags; |
| 64 | int ret = 0; |
| 65 | |
Jiri Slaby | fbadf70a | 2021-05-05 11:19:07 +0200 | [diff] [blame] | 66 | if (new_ldisc->num < N_TTY || new_ldisc->num >= NR_LDISCS) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 67 | return -EINVAL; |
| 68 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 69 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Jiri Slaby | fbadf70a | 2021-05-05 11:19:07 +0200 | [diff] [blame] | 70 | tty_ldiscs[new_ldisc->num] = new_ldisc; |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 71 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 72 | |
| 73 | return ret; |
| 74 | } |
| 75 | EXPORT_SYMBOL(tty_register_ldisc); |
| 76 | |
| 77 | /** |
| 78 | * tty_unregister_ldisc - unload a line discipline |
Baokun Li | e212955 | 2021-06-08 10:48:43 +0800 | [diff] [blame] | 79 | * @ldisc: ldisc number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 80 | * |
| 81 | * Remove a line discipline from the kernel providing it is not |
| 82 | * currently in use. |
| 83 | * |
| 84 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 85 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 86 | */ |
| 87 | |
Jiri Slaby | f6f1959 | 2021-05-05 11:19:12 +0200 | [diff] [blame] | 88 | void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 89 | { |
| 90 | unsigned long flags; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 91 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 92 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Jiri Slaby | 1947520 | 2021-05-05 11:19:10 +0200 | [diff] [blame] | 93 | tty_ldiscs[ldisc->num] = NULL; |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 94 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 95 | } |
| 96 | EXPORT_SYMBOL(tty_unregister_ldisc); |
| 97 | |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 98 | static struct tty_ldisc_ops *get_ldops(int disc) |
| 99 | { |
| 100 | unsigned long flags; |
| 101 | struct tty_ldisc_ops *ldops, *ret; |
| 102 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 103 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 104 | ret = ERR_PTR(-EINVAL); |
| 105 | ldops = tty_ldiscs[disc]; |
| 106 | if (ldops) { |
| 107 | ret = ERR_PTR(-EAGAIN); |
Jiri Slaby | 1947520 | 2021-05-05 11:19:10 +0200 | [diff] [blame] | 108 | if (try_module_get(ldops->owner)) |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 109 | ret = ldops; |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 110 | } |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 111 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 112 | return ret; |
| 113 | } |
| 114 | |
| 115 | static void put_ldops(struct tty_ldisc_ops *ldops) |
| 116 | { |
| 117 | unsigned long flags; |
| 118 | |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 119 | raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 120 | module_put(ldops->owner); |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 121 | raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 122 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 123 | |
Lee Jones | 8eddcca | 2020-11-12 10:58:54 +0000 | [diff] [blame] | 124 | static int tty_ldisc_autoload = IS_BUILTIN(CONFIG_LDISC_AUTOLOAD); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 125 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 126 | * tty_ldisc_get - take a reference to an ldisc |
Lee Jones | 8a3bdec | 2020-11-04 19:35:42 +0000 | [diff] [blame] | 127 | * @tty: tty device |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 128 | * @disc: ldisc number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 129 | * |
| 130 | * Takes a reference to a line discipline. Deals with refcounts and |
Peter Hurley | c0cc1c5 | 2016-01-10 22:40:59 -0800 | [diff] [blame] | 131 | * module locking counts. |
| 132 | * |
| 133 | * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or |
| 134 | * if the discipline is not registered |
| 135 | * -EAGAIN if request_module() failed to load or register the |
Xiaofei Tan | b895854 | 2021-04-07 15:06:50 +0800 | [diff] [blame] | 136 | * discipline |
Peter Hurley | c0cc1c5 | 2016-01-10 22:40:59 -0800 | [diff] [blame] | 137 | * -ENOMEM if allocation failure |
| 138 | * |
| 139 | * Otherwise, returns a pointer to the discipline and bumps the |
| 140 | * ref count |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 141 | * |
| 142 | * Locking: |
Peter Hurley | 137084b | 2013-06-15 07:04:46 -0400 | [diff] [blame] | 143 | * takes tty_ldiscs_lock to guard against ldisc races |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 144 | */ |
| 145 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 146 | 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] | 147 | { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 148 | struct tty_ldisc *ld; |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 149 | struct tty_ldisc_ops *ldops; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 150 | |
| 151 | if (disc < N_TTY || disc >= NR_LDISCS) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 152 | return ERR_PTR(-EINVAL); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 153 | |
| 154 | /* |
| 155 | * Get the ldisc ops - we may need to request them to be loaded |
| 156 | * dynamically and try again. |
| 157 | */ |
| 158 | ldops = get_ldops(disc); |
| 159 | if (IS_ERR(ldops)) { |
Greg Kroah-Hartman | 7c0cca7 | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 160 | if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload) |
| 161 | return ERR_PTR(-EPERM); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 162 | request_module("tty-ldisc-%d", disc); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 163 | ldops = get_ldops(disc); |
| 164 | if (IS_ERR(ldops)) |
| 165 | return ERR_CAST(ldops); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 166 | } |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 167 | |
Tetsuo Handa | bcdd0ca | 2018-04-25 20:12:31 +0900 | [diff] [blame] | 168 | /* |
| 169 | * There is no way to handle allocation failure of only 16 bytes. |
| 170 | * Let's simplify error handling and save more memory. |
| 171 | */ |
| 172 | ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL); |
Linus Torvalds | 182274f | 2009-08-03 16:01:28 -0700 | [diff] [blame] | 173 | ld->ops = ldops; |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 174 | ld->tty = tty; |
Ivo Sieben | 1541f84 | 2012-05-03 14:37:43 +0200 | [diff] [blame] | 175 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 176 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 177 | } |
| 178 | |
Lee Jones | 8eddcca | 2020-11-12 10:58:54 +0000 | [diff] [blame] | 179 | /* |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 180 | * tty_ldisc_put - release the ldisc |
| 181 | * |
| 182 | * Complement of tty_ldisc_get(). |
| 183 | */ |
Denys Vlasenko | cb128f6 | 2015-10-27 17:40:02 +0100 | [diff] [blame] | 184 | static void tty_ldisc_put(struct tty_ldisc *ld) |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 185 | { |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 186 | if (WARN_ON_ONCE(!ld)) |
| 187 | return; |
| 188 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 189 | put_ldops(ld->ops); |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 190 | kfree(ld); |
Peter Hurley | 734de24 | 2013-03-11 16:44:43 -0400 | [diff] [blame] | 191 | } |
| 192 | |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 193 | 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] | 194 | { |
| 195 | return (*pos < NR_LDISCS) ? pos : NULL; |
| 196 | } |
| 197 | |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 198 | 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] | 199 | { |
| 200 | (*pos)++; |
| 201 | return (*pos < NR_LDISCS) ? pos : NULL; |
| 202 | } |
| 203 | |
| 204 | static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) |
| 205 | { |
| 206 | } |
| 207 | |
| 208 | static int tty_ldiscs_seq_show(struct seq_file *m, void *v) |
| 209 | { |
| 210 | int i = *(loff_t *)v; |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 211 | struct tty_ldisc_ops *ldops; |
Alan Cox | 852e99d | 2009-06-11 12:51:41 +0100 | [diff] [blame] | 212 | |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 213 | ldops = get_ldops(i); |
| 214 | if (IS_ERR(ldops)) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 215 | return 0; |
Linus Torvalds | f0de0e8 | 2009-08-03 16:00:15 -0700 | [diff] [blame] | 216 | seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); |
| 217 | put_ldops(ldops); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 218 | return 0; |
| 219 | } |
| 220 | |
Christoph Hellwig | fddda2b | 2018-04-13 19:44:18 +0200 | [diff] [blame] | 221 | const struct seq_operations tty_ldiscs_seq_ops = { |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 222 | .start = tty_ldiscs_seq_start, |
| 223 | .next = tty_ldiscs_seq_next, |
| 224 | .stop = tty_ldiscs_seq_stop, |
| 225 | .show = tty_ldiscs_seq_show, |
| 226 | }; |
| 227 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 228 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 229 | * tty_ldisc_ref_wait - wait for the tty ldisc |
| 230 | * @tty: tty device |
| 231 | * |
| 232 | * Dereference the line discipline for the terminal and take a |
| 233 | * reference to it. If the line discipline is in flux then |
| 234 | * wait patiently until it changes. |
| 235 | * |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 236 | * Returns: NULL if the tty has been hungup and not re-opened with |
| 237 | * a new file descriptor, otherwise valid ldisc reference |
| 238 | * |
Lee Jones | 8eddcca | 2020-11-12 10:58:54 +0000 | [diff] [blame] | 239 | * Note 1: Must not be called from an IRQ/timer context. The caller |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 240 | * must also be careful not to hold other locks that will deadlock |
| 241 | * against a discipline change, such as an existing ldisc reference |
| 242 | * (which we check for) |
| 243 | * |
Lee Jones | 8eddcca | 2020-11-12 10:58:54 +0000 | [diff] [blame] | 244 | * Note 2: a file_operations routine (read/poll/write) should use this |
Peter Hurley | e55afd1 | 2016-01-10 22:41:01 -0800 | [diff] [blame] | 245 | * function to wait for any ldisc lifetime events to finish. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 246 | */ |
| 247 | |
| 248 | struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) |
| 249 | { |
Dmitry Vyukov | a4a3e06 | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 250 | struct tty_ldisc *ld; |
| 251 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 252 | ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); |
Dmitry Vyukov | a4a3e06 | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 253 | ld = tty->ldisc; |
| 254 | if (!ld) |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 255 | ldsem_up_read(&tty->ldisc_sem); |
Dmitry Vyukov | a4a3e06 | 2017-03-04 13:46:12 +0100 | [diff] [blame] | 256 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 257 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 258 | EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); |
| 259 | |
| 260 | /** |
| 261 | * tty_ldisc_ref - get 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 | * return NULL. Can be called from IRQ and timer functions. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 267 | */ |
| 268 | |
| 269 | struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) |
| 270 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 271 | struct tty_ldisc *ld = NULL; |
| 272 | |
| 273 | if (ldsem_down_read_trylock(&tty->ldisc_sem)) { |
| 274 | ld = tty->ldisc; |
| 275 | if (!ld) |
| 276 | ldsem_up_read(&tty->ldisc_sem); |
| 277 | } |
| 278 | return ld; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 279 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 280 | EXPORT_SYMBOL_GPL(tty_ldisc_ref); |
| 281 | |
| 282 | /** |
| 283 | * tty_ldisc_deref - free a tty ldisc reference |
| 284 | * @ld: reference to free up |
| 285 | * |
| 286 | * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May |
| 287 | * be called in IRQ context. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 288 | */ |
| 289 | |
| 290 | void tty_ldisc_deref(struct tty_ldisc *ld) |
| 291 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 292 | ldsem_up_read(&ld->tty->ldisc_sem); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 293 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 294 | EXPORT_SYMBOL_GPL(tty_ldisc_deref); |
| 295 | |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 296 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 297 | static inline int |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 298 | __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 299 | { |
| 300 | return ldsem_down_write(&tty->ldisc_sem, timeout); |
| 301 | } |
| 302 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 303 | static inline int |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 304 | __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 305 | { |
| 306 | return ldsem_down_write_nested(&tty->ldisc_sem, |
| 307 | LDISC_SEM_OTHER, timeout); |
| 308 | } |
| 309 | |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 310 | static inline void __tty_ldisc_unlock(struct tty_struct *tty) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 311 | { |
Guillaume Gomez | 52772ea | 2015-10-04 21:19:18 +0200 | [diff] [blame] | 312 | ldsem_up_write(&tty->ldisc_sem); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 313 | } |
| 314 | |
Gaurav Kohli | b027e22 | 2018-01-23 13:16:34 +0530 | [diff] [blame] | 315 | int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 316 | { |
| 317 | int ret; |
| 318 | |
Dmitry Safonov | c96cf92 | 2018-11-01 00:24:48 +0000 | [diff] [blame] | 319 | /* Kindly asking blocked readers to release the read side */ |
| 320 | set_bit(TTY_LDISC_CHANGING, &tty->flags); |
| 321 | wake_up_interruptible_all(&tty->read_wait); |
| 322 | wake_up_interruptible_all(&tty->write_wait); |
| 323 | |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 324 | ret = __tty_ldisc_lock(tty, timeout); |
| 325 | if (!ret) |
| 326 | return -EBUSY; |
| 327 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
| 328 | return 0; |
| 329 | } |
| 330 | |
Gaurav Kohli | b027e22 | 2018-01-23 13:16:34 +0530 | [diff] [blame] | 331 | void tty_ldisc_unlock(struct tty_struct *tty) |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 332 | { |
| 333 | clear_bit(TTY_LDISC_HALTED, &tty->flags); |
Dmitry Safonov | c96cf92 | 2018-11-01 00:24:48 +0000 | [diff] [blame] | 334 | /* Can be cleared here - ldisc_unlock will wake up writers firstly */ |
| 335 | clear_bit(TTY_LDISC_CHANGING, &tty->flags); |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 336 | __tty_ldisc_unlock(tty); |
| 337 | } |
| 338 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 339 | static int |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 340 | tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, |
| 341 | unsigned long timeout) |
| 342 | { |
| 343 | int ret; |
| 344 | |
| 345 | if (tty < tty2) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 346 | ret = __tty_ldisc_lock(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 347 | if (ret) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 348 | ret = __tty_ldisc_lock_nested(tty2, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 349 | if (!ret) |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 350 | __tty_ldisc_unlock(tty); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 351 | } |
| 352 | } else { |
| 353 | /* if this is possible, it has lots of implications */ |
| 354 | WARN_ON_ONCE(tty == tty2); |
| 355 | if (tty2 && tty != tty2) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 356 | ret = __tty_ldisc_lock(tty2, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 357 | if (ret) { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 358 | ret = __tty_ldisc_lock_nested(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 359 | if (!ret) |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 360 | __tty_ldisc_unlock(tty2); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 361 | } |
| 362 | } else |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 363 | ret = __tty_ldisc_lock(tty, timeout); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 364 | } |
| 365 | |
| 366 | if (!ret) |
| 367 | return -EBUSY; |
| 368 | |
| 369 | set_bit(TTY_LDISC_HALTED, &tty->flags); |
| 370 | if (tty2) |
| 371 | set_bit(TTY_LDISC_HALTED, &tty2->flags); |
| 372 | return 0; |
| 373 | } |
| 374 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 375 | 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] | 376 | { |
| 377 | tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); |
| 378 | } |
| 379 | |
Peter Hurley | c2bb524 | 2016-01-09 21:13:51 -0800 | [diff] [blame] | 380 | static void tty_ldisc_unlock_pair(struct tty_struct *tty, |
| 381 | struct tty_struct *tty2) |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 382 | { |
Peter Hurley | e80a10e | 2014-11-05 12:13:06 -0500 | [diff] [blame] | 383 | __tty_ldisc_unlock(tty); |
Peter Hurley | d2c4389 | 2013-06-15 07:04:47 -0400 | [diff] [blame] | 384 | if (tty2) |
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 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 388 | /** |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 389 | * tty_ldisc_flush - flush line discipline queue |
| 390 | * @tty: tty |
| 391 | * |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 392 | * Flush the line discipline queue (if any) and the tty flip buffers |
| 393 | * for this tty. |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 394 | */ |
| 395 | |
| 396 | void tty_ldisc_flush(struct tty_struct *tty) |
| 397 | { |
| 398 | struct tty_ldisc *ld = tty_ldisc_ref(tty); |
Peter Hurley | 86c80a8 | 2014-11-05 12:13:09 -0500 | [diff] [blame] | 399 | |
| 400 | tty_buffer_flush(tty, ld); |
| 401 | if (ld) |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 402 | tty_ldisc_deref(ld); |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 403 | } |
Alan Cox | f2c4c65 | 2009-06-11 12:50:58 +0100 | [diff] [blame] | 404 | EXPORT_SYMBOL_GPL(tty_ldisc_flush); |
| 405 | |
| 406 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 407 | * tty_set_termios_ldisc - set ldisc field |
| 408 | * @tty: tty structure |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 409 | * @disc: line discipline number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 410 | * |
| 411 | * This is probably overkill for real world processors but |
| 412 | * they are not on hot paths so a little discipline won't do |
| 413 | * any harm. |
| 414 | * |
Peter Hurley | dd42bf1 | 2015-11-27 14:30:21 -0500 | [diff] [blame] | 415 | * The line discipline-related tty_struct fields are reset to |
| 416 | * prevent the ldisc driver from re-using stale information for |
| 417 | * the new ldisc instance. |
| 418 | * |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 419 | * Locking: takes termios_rwsem |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 420 | */ |
| 421 | |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 422 | static void tty_set_termios_ldisc(struct tty_struct *tty, int disc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 423 | { |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 424 | down_write(&tty->termios_rwsem); |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 425 | tty->termios.c_line = disc; |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 426 | up_write(&tty->termios_rwsem); |
Peter Hurley | dd42bf1 | 2015-11-27 14:30:21 -0500 | [diff] [blame] | 427 | |
| 428 | tty->disc_data = NULL; |
| 429 | tty->receive_room = 0; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 430 | } |
| 431 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 432 | /** |
| 433 | * tty_ldisc_open - open a line discipline |
| 434 | * @tty: tty we are opening the ldisc on |
| 435 | * @ld: discipline to open |
| 436 | * |
| 437 | * A helper opening method. Also a convenient debugging and check |
| 438 | * point. |
Arnd Bergmann | ec79d60 | 2010-06-01 22:53:01 +0200 | [diff] [blame] | 439 | * |
| 440 | * Locking: always called with BTM already held. |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 441 | */ |
| 442 | |
| 443 | static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) |
| 444 | { |
| 445 | WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 446 | if (ld->ops->open) { |
| 447 | int ret; |
Xiaofei Tan | 5d3945e | 2021-04-07 15:06:46 +0800 | [diff] [blame] | 448 | /* BTM here locks versus a hangup event */ |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 449 | ret = ld->ops->open(tty); |
Jiri Slaby | 7f90cfc | 2010-11-25 00:27:54 +0100 | [diff] [blame] | 450 | if (ret) |
| 451 | clear_bit(TTY_LDISC_OPEN, &tty->flags); |
Peter Hurley | fb6edc9 | 2015-07-12 22:49:12 -0400 | [diff] [blame] | 452 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 453 | tty_ldisc_debug(tty, "%p: opened\n", ld); |
Alan Cox | f18f949 | 2009-11-30 13:18:35 +0000 | [diff] [blame] | 454 | return ret; |
| 455 | } |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 456 | return 0; |
| 457 | } |
| 458 | |
| 459 | /** |
| 460 | * tty_ldisc_close - close a line discipline |
| 461 | * @tty: tty we are opening the ldisc on |
| 462 | * @ld: discipline to close |
| 463 | * |
| 464 | * A helper close method. Also a convenient debugging and check |
| 465 | * point. |
| 466 | */ |
| 467 | |
| 468 | static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) |
| 469 | { |
Nikolay Borisov | 9ffbe8a | 2019-05-31 13:06:51 +0300 | [diff] [blame] | 470 | lockdep_assert_held_write(&tty->ldisc_sem); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 471 | WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); |
| 472 | clear_bit(TTY_LDISC_OPEN, &tty->flags); |
| 473 | if (ld->ops->close) |
| 474 | ld->ops->close(tty); |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 475 | tty_ldisc_debug(tty, "%p: closed\n", ld); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 476 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 477 | |
| 478 | /** |
Alan Cox | 8a8dabf | 2017-06-02 13:49:30 +0100 | [diff] [blame] | 479 | * tty_ldisc_failto - helper for ldisc failback |
| 480 | * @tty: tty to open the ldisc on |
| 481 | * @ld: ldisc we are trying to fail back to |
| 482 | * |
| 483 | * Helper to try and recover a tty when switching back to the old |
| 484 | * ldisc fails and we need something attached. |
| 485 | */ |
| 486 | |
| 487 | static int tty_ldisc_failto(struct tty_struct *tty, int ld) |
| 488 | { |
| 489 | struct tty_ldisc *disc = tty_ldisc_get(tty, ld); |
| 490 | int r; |
| 491 | |
Nikolay Borisov | 9ffbe8a | 2019-05-31 13:06:51 +0300 | [diff] [blame] | 492 | lockdep_assert_held_write(&tty->ldisc_sem); |
Alan Cox | 8a8dabf | 2017-06-02 13:49:30 +0100 | [diff] [blame] | 493 | if (IS_ERR(disc)) |
| 494 | return PTR_ERR(disc); |
| 495 | tty->ldisc = disc; |
| 496 | tty_set_termios_ldisc(tty, ld); |
Xiaofei Tan | 408795b | 2021-04-07 15:06:49 +0800 | [diff] [blame] | 497 | r = tty_ldisc_open(tty, disc); |
| 498 | if (r < 0) |
Alan Cox | 8a8dabf | 2017-06-02 13:49:30 +0100 | [diff] [blame] | 499 | tty_ldisc_put(disc); |
| 500 | return r; |
| 501 | } |
| 502 | |
| 503 | /** |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 504 | * tty_ldisc_restore - helper for tty ldisc change |
| 505 | * @tty: tty to recover |
| 506 | * @old: previous ldisc |
| 507 | * |
| 508 | * Restore the previous line discipline or N_TTY when a line discipline |
| 509 | * change fails due to an open error |
| 510 | */ |
| 511 | |
| 512 | static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) |
| 513 | { |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 514 | /* There is an outstanding reference here so this is safe */ |
Tetsuo Handa | 598c2d4 | 2018-04-16 20:06:34 +0900 | [diff] [blame] | 515 | if (tty_ldisc_failto(tty, old->ops->num) < 0) { |
| 516 | const char *name = tty_name(tty); |
| 517 | |
| 518 | pr_warn("Falling back ldisc for %s.\n", name); |
Xiaofei Tan | 72a8dcd | 2021-04-07 15:06:48 +0800 | [diff] [blame] | 519 | /* |
| 520 | * The traditional behaviour is to fall back to N_TTY, we |
| 521 | * want to avoid falling back to N_NULL unless we have no |
| 522 | * choice to avoid the risk of breaking anything |
| 523 | */ |
Alan Cox | 8a8dabf | 2017-06-02 13:49:30 +0100 | [diff] [blame] | 524 | if (tty_ldisc_failto(tty, N_TTY) < 0 && |
| 525 | tty_ldisc_failto(tty, N_NULL) < 0) |
Tetsuo Handa | 598c2d4 | 2018-04-16 20:06:34 +0900 | [diff] [blame] | 526 | panic("Couldn't open N_NULL ldisc for %s.", name); |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 527 | } |
| 528 | } |
| 529 | |
| 530 | /** |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 531 | * tty_set_ldisc - set line discipline |
| 532 | * @tty: the terminal to set |
Jiri Slaby | fa44195 | 2020-08-18 10:56:51 +0200 | [diff] [blame] | 533 | * @disc: the line discipline number |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 534 | * |
| 535 | * 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] | 536 | * context. The ldisc change logic has to protect itself against any |
| 537 | * overlapping ldisc change (including on the other end of pty pairs), |
| 538 | * 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] | 539 | */ |
| 540 | |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 541 | int tty_set_ldisc(struct tty_struct *tty, int disc) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 542 | { |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 543 | int retval; |
| 544 | struct tty_ldisc *old_ldisc, *new_ldisc; |
| 545 | |
| 546 | new_ldisc = tty_ldisc_get(tty, disc); |
| 547 | if (IS_ERR(new_ldisc)) |
| 548 | return PTR_ERR(new_ldisc); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 549 | |
Peter Hurley | c8483bc | 2014-11-05 12:12:45 -0500 | [diff] [blame] | 550 | tty_lock(tty); |
Peter Hurley | 276a661 | 2014-11-05 12:13:08 -0500 | [diff] [blame] | 551 | retval = tty_ldisc_lock(tty, 5 * HZ); |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 552 | if (retval) |
| 553 | goto err; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 554 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 555 | if (!tty->ldisc) { |
| 556 | retval = -EIO; |
| 557 | goto out; |
| 558 | } |
| 559 | |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 560 | /* Check the no-op case */ |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 561 | if (tty->ldisc->ops->num == disc) |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 562 | goto out; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 563 | |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 564 | if (test_bit(TTY_HUPPED, &tty->flags)) { |
| 565 | /* We were raced by hangup */ |
| 566 | retval = -EIO; |
| 567 | goto out; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 568 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 569 | |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 570 | old_ldisc = tty->ldisc; |
| 571 | |
| 572 | /* Shutdown the old discipline. */ |
| 573 | tty_ldisc_close(tty, old_ldisc); |
| 574 | |
| 575 | /* Now set up the new line discipline. */ |
| 576 | tty->ldisc = new_ldisc; |
| 577 | tty_set_termios_ldisc(tty, disc); |
| 578 | |
| 579 | retval = tty_ldisc_open(tty, new_ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 580 | if (retval < 0) { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 581 | /* Back to the old one or N_TTY if we can't */ |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 582 | tty_ldisc_put(new_ldisc); |
| 583 | tty_ldisc_restore(tty, old_ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 584 | } |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 585 | |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 586 | if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) { |
Peter Hurley | 9191aaa | 2014-11-05 13:11:41 -0500 | [diff] [blame] | 587 | down_read(&tty->termios_rwsem); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 588 | tty->ops->set_ldisc(tty); |
Peter Hurley | 9191aaa | 2014-11-05 13:11:41 -0500 | [diff] [blame] | 589 | up_read(&tty->termios_rwsem); |
| 590 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 591 | |
Xiaofei Tan | 72a8dcd | 2021-04-07 15:06:48 +0800 | [diff] [blame] | 592 | /* |
| 593 | * At this point we hold a reference to the new ldisc and a |
| 594 | * reference to the old ldisc, or we hold two references to |
| 595 | * the old ldisc (if it was restored as part of error cleanup |
| 596 | * above). In either case, releasing a single reference from |
| 597 | * the old ldisc is correct. |
| 598 | */ |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 599 | new_ldisc = old_ldisc; |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 600 | out: |
Peter Hurley | 276a661 | 2014-11-05 12:13:08 -0500 | [diff] [blame] | 601 | tty_ldisc_unlock(tty); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 602 | |
Xiaofei Tan | 72a8dcd | 2021-04-07 15:06:48 +0800 | [diff] [blame] | 603 | /* |
| 604 | * Restart the work queue in case no characters kick it off. Safe if |
| 605 | * already running |
| 606 | */ |
Peter Hurley | 17a6921 | 2015-11-08 07:53:06 -0500 | [diff] [blame] | 607 | tty_buffer_restart_work(tty->port); |
Peter Hurley | 63d8cb3 | 2015-11-08 09:29:38 -0500 | [diff] [blame] | 608 | err: |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 609 | tty_ldisc_put(new_ldisc); /* drop the extra reference */ |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 610 | tty_unlock(tty); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 611 | return retval; |
| 612 | } |
Okash Khawaja | 1ab92da | 2017-05-15 18:45:33 +0100 | [diff] [blame] | 613 | EXPORT_SYMBOL_GPL(tty_set_ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 614 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 615 | /** |
Peter Hurley | 6ffeb4b | 2016-01-10 22:41:03 -0800 | [diff] [blame] | 616 | * tty_ldisc_kill - teardown ldisc |
| 617 | * @tty: tty being released |
| 618 | * |
| 619 | * Perform final close of the ldisc and reset tty->ldisc |
| 620 | */ |
| 621 | static void tty_ldisc_kill(struct tty_struct *tty) |
| 622 | { |
Nikolay Borisov | 9ffbe8a | 2019-05-31 13:06:51 +0300 | [diff] [blame] | 623 | lockdep_assert_held_write(&tty->ldisc_sem); |
Peter Hurley | 6ffeb4b | 2016-01-10 22:41:03 -0800 | [diff] [blame] | 624 | if (!tty->ldisc) |
| 625 | return; |
| 626 | /* |
| 627 | * Now kill off the ldisc |
| 628 | */ |
| 629 | tty_ldisc_close(tty, tty->ldisc); |
| 630 | tty_ldisc_put(tty->ldisc); |
| 631 | /* Force an oops if we mess this up */ |
| 632 | tty->ldisc = NULL; |
| 633 | } |
| 634 | |
| 635 | /** |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 636 | * tty_reset_termios - reset terminal state |
| 637 | * @tty: tty to reset |
| 638 | * |
| 639 | * Restore a terminal to the driver default state. |
| 640 | */ |
| 641 | |
| 642 | static void tty_reset_termios(struct tty_struct *tty) |
| 643 | { |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 644 | down_write(&tty->termios_rwsem); |
Alan Cox | adc8d74 | 2012-07-14 15:31:47 +0100 | [diff] [blame] | 645 | tty->termios = tty->driver->init_termios; |
| 646 | tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); |
| 647 | tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); |
Peter Hurley | 6a1c068 | 2013-06-15 09:14:23 -0400 | [diff] [blame] | 648 | up_write(&tty->termios_rwsem); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 649 | } |
| 650 | |
| 651 | |
| 652 | /** |
| 653 | * tty_ldisc_reinit - reinitialise the tty ldisc |
| 654 | * @tty: tty to reinit |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 655 | * @disc: line discipline to reinitialize |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 656 | * |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 657 | * Completely reinitialize the line discipline state, by closing the |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 658 | * current instance, if there is one, and opening a new instance. If |
| 659 | * an error occurs opening the new non-N_TTY instance, the instance |
| 660 | * is dropped and tty->ldisc reset to NULL. The caller can then retry |
| 661 | * with N_TTY instead. |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 662 | * |
| 663 | * Returns 0 if successful, otherwise error code < 0 |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 664 | */ |
| 665 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 666 | int tty_ldisc_reinit(struct tty_struct *tty, int disc) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 667 | { |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 668 | struct tty_ldisc *ld; |
| 669 | int retval; |
Philippe Rétornaz | 1c95ba1 | 2010-10-27 17:13:21 +0200 | [diff] [blame] | 670 | |
Nikolay Borisov | 9ffbe8a | 2019-05-31 13:06:51 +0300 | [diff] [blame] | 671 | lockdep_assert_held_write(&tty->ldisc_sem); |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 672 | ld = tty_ldisc_get(tty, disc); |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 673 | if (IS_ERR(ld)) { |
| 674 | BUG_ON(disc == N_TTY); |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 675 | return PTR_ERR(ld); |
Greg Kroah-Hartman | a8983d0 | 2017-04-14 10:57:52 +0200 | [diff] [blame] | 676 | } |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 677 | |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 678 | if (tty->ldisc) { |
| 679 | tty_ldisc_close(tty, tty->ldisc); |
| 680 | tty_ldisc_put(tty->ldisc); |
| 681 | } |
| 682 | |
| 683 | /* switch the line discipline */ |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 684 | tty->ldisc = ld; |
Peter Hurley | c12da96 | 2016-01-10 22:41:04 -0800 | [diff] [blame] | 685 | tty_set_termios_ldisc(tty, disc); |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 686 | retval = tty_ldisc_open(tty, tty->ldisc); |
| 687 | if (retval) { |
Johannes Weiner | e65c62b | 2017-10-13 15:58:08 -0700 | [diff] [blame] | 688 | tty_ldisc_put(tty->ldisc); |
| 689 | tty->ldisc = NULL; |
Peter Hurley | 7896f30 | 2016-01-10 22:41:05 -0800 | [diff] [blame] | 690 | } |
| 691 | return retval; |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 692 | } |
| 693 | |
| 694 | /** |
| 695 | * tty_ldisc_hangup - hangup ldisc reset |
| 696 | * @tty: tty being hung up |
Lee Jones | 8eddcca | 2020-11-12 10:58:54 +0000 | [diff] [blame] | 697 | * @reinit: whether to re-initialise the tty |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 698 | * |
| 699 | * Some tty devices reset their termios when they receive a hangup |
| 700 | * event. In that situation we must also switch back to N_TTY properly |
| 701 | * before we reset the termios data. |
| 702 | * |
| 703 | * Locking: We can take the ldisc mutex as the rest of the code is |
| 704 | * careful to allow for this. |
| 705 | * |
| 706 | * In the pty pair case this occurs in the close() path of the |
| 707 | * tty itself so we must be careful about locking rules. |
| 708 | */ |
| 709 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 710 | void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 711 | { |
| 712 | struct tty_ldisc *ld; |
| 713 | |
Peter Hurley | a570a49 | 2016-01-10 22:41:02 -0800 | [diff] [blame] | 714 | tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc); |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 715 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 716 | ld = tty_ldisc_ref(tty); |
| 717 | if (ld != NULL) { |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 718 | if (ld->ops->flush_buffer) |
| 719 | ld->ops->flush_buffer(tty); |
| 720 | tty_driver_flush_buffer(tty); |
| 721 | if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && |
| 722 | ld->ops->write_wakeup) |
| 723 | ld->ops->write_wakeup(tty); |
| 724 | if (ld->ops->hangup) |
| 725 | ld->ops->hangup(tty); |
| 726 | tty_ldisc_deref(ld); |
| 727 | } |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 728 | |
Linus Torvalds | a9a0884 | 2018-02-11 14:34:03 -0800 | [diff] [blame] | 729 | wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT); |
| 730 | wake_up_interruptible_poll(&tty->read_wait, EPOLLIN); |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 731 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 732 | /* |
| 733 | * Shutdown the current line discipline, and reset it to |
Alan Cox | 638b964 | 2010-02-08 10:09:26 +0000 | [diff] [blame] | 734 | * N_TTY if need be. |
| 735 | * |
| 736 | * Avoid racing set_ldisc or tty_ldisc_release |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 737 | */ |
Peter Hurley | fae76e9 | 2014-11-05 12:13:07 -0500 | [diff] [blame] | 738 | tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); |
Arnd Bergmann | 60af22d | 2010-06-01 22:53:06 +0200 | [diff] [blame] | 739 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 740 | if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) |
Alan Cox | 638b964 | 2010-02-08 10:09:26 +0000 | [diff] [blame] | 741 | tty_reset_termios(tty); |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 742 | |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 743 | if (tty->ldisc) { |
| 744 | if (reinit) { |
Johannes Weiner | e65c62b | 2017-10-13 15:58:08 -0700 | [diff] [blame] | 745 | if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0 && |
| 746 | tty_ldisc_reinit(tty, N_TTY) < 0) |
| 747 | WARN_ON(tty_ldisc_reinit(tty, N_NULL) < 0); |
Peter Hurley | 892d1fa | 2016-01-10 22:41:06 -0800 | [diff] [blame] | 748 | } else |
| 749 | tty_ldisc_kill(tty); |
| 750 | } |
| 751 | tty_ldisc_unlock(tty); |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 752 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 753 | |
| 754 | /** |
| 755 | * tty_ldisc_setup - open line discipline |
| 756 | * @tty: tty being shut down |
| 757 | * @o_tty: pair tty for pty/tty pairs |
| 758 | * |
| 759 | * 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] | 760 | * line disciplines and bind them to the tty. This has no locking issues |
| 761 | * as the device isn't yet active. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 762 | */ |
| 763 | |
| 764 | int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) |
| 765 | { |
Peter Hurley | 9de2a7c | 2016-01-10 22:41:08 -0800 | [diff] [blame] | 766 | int retval = tty_ldisc_open(tty, tty->ldisc); |
Xiaofei Tan | d723835 | 2021-04-07 15:06:47 +0800 | [diff] [blame] | 767 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 768 | if (retval) |
| 769 | return retval; |
| 770 | |
| 771 | if (o_tty) { |
Dmitry Safonov | 110b892 | 2018-11-01 00:24:51 +0000 | [diff] [blame] | 772 | /* |
| 773 | * Called without o_tty->ldisc_sem held, as o_tty has been |
| 774 | * just allocated and no one has a reference to it. |
| 775 | */ |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 776 | retval = tty_ldisc_open(o_tty, o_tty->ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 777 | if (retval) { |
Peter Hurley | 9de2a7c | 2016-01-10 22:41:08 -0800 | [diff] [blame] | 778 | tty_ldisc_close(tty, tty->ldisc); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 779 | return retval; |
| 780 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 781 | } |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 782 | return 0; |
| 783 | } |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 784 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 785 | /** |
| 786 | * tty_ldisc_release - release line discipline |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 787 | * @tty: tty being shut down (or one end of pty pair) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 788 | * |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 789 | * 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] | 790 | * 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] | 791 | */ |
| 792 | |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 793 | void tty_ldisc_release(struct tty_struct *tty) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 794 | { |
Peter Hurley | 62462ae | 2014-11-05 12:12:58 -0500 | [diff] [blame] | 795 | struct tty_struct *o_tty = tty->link; |
| 796 | |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 797 | /* |
Peter Hurley | a2965b7 | 2013-03-11 16:44:35 -0400 | [diff] [blame] | 798 | * Shutdown this line discipline. As this is the final close, |
| 799 | * it does not race with the set_ldisc code path. |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 800 | */ |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 801 | |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 802 | tty_ldisc_lock_pair(tty, o_tty); |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 803 | tty_ldisc_kill(tty); |
Alan Cox | 89c8d91 | 2012-08-08 16:30:13 +0100 | [diff] [blame] | 804 | if (o_tty) |
| 805 | tty_ldisc_kill(o_tty); |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 806 | tty_ldisc_unlock_pair(tty, o_tty); |
| 807 | |
Xiaofei Tan | 72a8dcd | 2021-04-07 15:06:48 +0800 | [diff] [blame] | 808 | /* |
| 809 | * And the memory resources remaining (buffers, termios) will be |
| 810 | * disposed of when the kref hits zero |
| 811 | */ |
Peter Hurley | fc575ee | 2013-03-11 16:44:38 -0400 | [diff] [blame] | 812 | |
Peter Hurley | fb6edc9 | 2015-07-12 22:49:12 -0400 | [diff] [blame] | 813 | tty_ldisc_debug(tty, "released\n"); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 814 | } |
Okash Khawaja | 1ab92da | 2017-05-15 18:45:33 +0100 | [diff] [blame] | 815 | EXPORT_SYMBOL_GPL(tty_ldisc_release); |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 816 | |
| 817 | /** |
| 818 | * tty_ldisc_init - ldisc setup for new tty |
| 819 | * @tty: tty being allocated |
| 820 | * |
| 821 | * Set up the line discipline objects for a newly allocated tty. Note that |
| 822 | * the tty structure is not completely set up when this call is made. |
| 823 | */ |
| 824 | |
Tetsuo Handa | 903f9db | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 825 | int tty_ldisc_init(struct tty_struct *tty) |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 826 | { |
Peter Hurley | 3669752 | 2013-06-15 07:04:48 -0400 | [diff] [blame] | 827 | struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); |
Xiaofei Tan | d723835 | 2021-04-07 15:06:47 +0800 | [diff] [blame] | 828 | |
Alan Cox | c65c9bc | 2009-06-11 12:50:12 +0100 | [diff] [blame] | 829 | if (IS_ERR(ld)) |
Tetsuo Handa | 903f9db | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 830 | return PTR_ERR(ld); |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 831 | tty->ldisc = ld; |
Tetsuo Handa | 903f9db | 2018-04-05 19:40:16 +0900 | [diff] [blame] | 832 | return 0; |
Alan Cox | 01e1abb | 2008-07-22 11:16:55 +0100 | [diff] [blame] | 833 | } |
| 834 | |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 835 | /** |
Peter Hurley | c8b710b | 2016-01-09 21:13:46 -0800 | [diff] [blame] | 836 | * tty_ldisc_deinit - ldisc cleanup for new tty |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 837 | * @tty: tty that was allocated recently |
| 838 | * |
| 839 | * The tty structure must not becompletely set up (tty_ldisc_setup) when |
| 840 | * this call is made. |
| 841 | */ |
| 842 | void tty_ldisc_deinit(struct tty_struct *tty) |
| 843 | { |
Dmitry Safonov | 110b892 | 2018-11-01 00:24:51 +0000 | [diff] [blame] | 844 | /* no ldisc_sem, tty is being destroyed */ |
Peter Hurley | c8b710b | 2016-01-09 21:13:46 -0800 | [diff] [blame] | 845 | if (tty->ldisc) |
| 846 | tty_ldisc_put(tty->ldisc); |
Peter Hurley | f4807045 | 2013-03-11 16:44:42 -0400 | [diff] [blame] | 847 | tty->ldisc = NULL; |
Jiri Slaby | 6716671 | 2011-03-23 10:48:35 +0100 | [diff] [blame] | 848 | } |
Greg Kroah-Hartman | 7c0cca7 | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 849 | |
Greg Kroah-Hartman | 7c0cca7 | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 850 | static struct ctl_table tty_table[] = { |
| 851 | { |
| 852 | .procname = "ldisc_autoload", |
| 853 | .data = &tty_ldisc_autoload, |
| 854 | .maxlen = sizeof(tty_ldisc_autoload), |
| 855 | .mode = 0644, |
| 856 | .proc_handler = proc_dointvec, |
Matteo Croce | eec4844 | 2019-07-18 15:58:50 -0700 | [diff] [blame] | 857 | .extra1 = SYSCTL_ZERO, |
| 858 | .extra2 = SYSCTL_ONE, |
Greg Kroah-Hartman | 7c0cca7 | 2019-01-21 17:26:42 +0100 | [diff] [blame] | 859 | }, |
| 860 | { } |
| 861 | }; |
| 862 | |
| 863 | static struct ctl_table tty_dir_table[] = { |
| 864 | { |
| 865 | .procname = "tty", |
| 866 | .mode = 0555, |
| 867 | .child = tty_table, |
| 868 | }, |
| 869 | { } |
| 870 | }; |
| 871 | |
| 872 | static struct ctl_table tty_root_table[] = { |
| 873 | { |
| 874 | .procname = "dev", |
| 875 | .mode = 0555, |
| 876 | .child = tty_dir_table, |
| 877 | }, |
| 878 | { } |
| 879 | }; |
| 880 | |
| 881 | void tty_sysctl_init(void) |
| 882 | { |
| 883 | register_sysctl_table(tty_root_table); |
| 884 | } |