1e3b3d0f5SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 296fd7ce5SGreg Kroah-Hartman #include <linux/types.h> 396fd7ce5SGreg Kroah-Hartman #include <linux/errno.h> 48b3ffa17SJiri Slaby #include <linux/kmod.h> 596fd7ce5SGreg Kroah-Hartman #include <linux/sched.h> 696fd7ce5SGreg Kroah-Hartman #include <linux/interrupt.h> 796fd7ce5SGreg Kroah-Hartman #include <linux/tty.h> 896fd7ce5SGreg Kroah-Hartman #include <linux/tty_driver.h> 996fd7ce5SGreg Kroah-Hartman #include <linux/file.h> 1096fd7ce5SGreg Kroah-Hartman #include <linux/mm.h> 1196fd7ce5SGreg Kroah-Hartman #include <linux/string.h> 1296fd7ce5SGreg Kroah-Hartman #include <linux/slab.h> 1396fd7ce5SGreg Kroah-Hartman #include <linux/poll.h> 1496fd7ce5SGreg Kroah-Hartman #include <linux/proc_fs.h> 1596fd7ce5SGreg Kroah-Hartman #include <linux/module.h> 1696fd7ce5SGreg Kroah-Hartman #include <linux/device.h> 1796fd7ce5SGreg Kroah-Hartman #include <linux/wait.h> 1896fd7ce5SGreg Kroah-Hartman #include <linux/bitops.h> 1996fd7ce5SGreg Kroah-Hartman #include <linux/seq_file.h> 2096fd7ce5SGreg Kroah-Hartman #include <linux/uaccess.h> 210c73c08eSJiri Slaby #include <linux/ratelimit.h> 2296fd7ce5SGreg Kroah-Hartman 23fc575ee6SPeter Hurley #undef LDISC_DEBUG_HANGUP 24fc575ee6SPeter Hurley 25fc575ee6SPeter Hurley #ifdef LDISC_DEBUG_HANGUP 260a6adc13SPeter Hurley #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) 27fc575ee6SPeter Hurley #else 28fc575ee6SPeter Hurley #define tty_ldisc_debug(tty, f, args...) 29fc575ee6SPeter Hurley #endif 30fc575ee6SPeter Hurley 31d2c43890SPeter Hurley /* lockdep nested classes for tty->ldisc_sem */ 32d2c43890SPeter Hurley enum { 33d2c43890SPeter Hurley LDISC_SEM_NORMAL, 34d2c43890SPeter Hurley LDISC_SEM_OTHER, 35d2c43890SPeter Hurley }; 36d2c43890SPeter Hurley 37d2c43890SPeter Hurley 3896fd7ce5SGreg Kroah-Hartman /* 3996fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 4096fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4196fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4296fd7ce5SGreg Kroah-Hartman */ 4396fd7ce5SGreg Kroah-Hartman 44137084bbSPeter Hurley static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); 4596fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 4696fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 4796fd7ce5SGreg Kroah-Hartman 4896fd7ce5SGreg Kroah-Hartman /** 4996fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 5096fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 5196fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 5296fd7ce5SGreg Kroah-Hartman * 5396fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 5496fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 5596fd7ce5SGreg Kroah-Hartman * from this point onwards. 5696fd7ce5SGreg Kroah-Hartman * 5796fd7ce5SGreg Kroah-Hartman * Locking: 58137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 5996fd7ce5SGreg Kroah-Hartman */ 6096fd7ce5SGreg Kroah-Hartman 6196fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 6296fd7ce5SGreg Kroah-Hartman { 6396fd7ce5SGreg Kroah-Hartman unsigned long flags; 6496fd7ce5SGreg Kroah-Hartman int ret = 0; 6596fd7ce5SGreg Kroah-Hartman 6696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 6796fd7ce5SGreg Kroah-Hartman return -EINVAL; 6896fd7ce5SGreg Kroah-Hartman 69137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 7096fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 7196fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 7296fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 73137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 7496fd7ce5SGreg Kroah-Hartman 7596fd7ce5SGreg Kroah-Hartman return ret; 7696fd7ce5SGreg Kroah-Hartman } 7796fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 7896fd7ce5SGreg Kroah-Hartman 7996fd7ce5SGreg Kroah-Hartman /** 8096fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 8196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 8296fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 8396fd7ce5SGreg Kroah-Hartman * 8496fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 8596fd7ce5SGreg Kroah-Hartman * currently in use. 8696fd7ce5SGreg Kroah-Hartman * 8796fd7ce5SGreg Kroah-Hartman * Locking: 88137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 8996fd7ce5SGreg Kroah-Hartman */ 9096fd7ce5SGreg Kroah-Hartman 9196fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 9296fd7ce5SGreg Kroah-Hartman { 9396fd7ce5SGreg Kroah-Hartman unsigned long flags; 9496fd7ce5SGreg Kroah-Hartman int ret = 0; 9596fd7ce5SGreg Kroah-Hartman 9696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 9796fd7ce5SGreg Kroah-Hartman return -EINVAL; 9896fd7ce5SGreg Kroah-Hartman 99137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 10096fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 10196fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 10296fd7ce5SGreg Kroah-Hartman else 10396fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 104137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 10596fd7ce5SGreg Kroah-Hartman 10696fd7ce5SGreg Kroah-Hartman return ret; 10796fd7ce5SGreg Kroah-Hartman } 10896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 10996fd7ce5SGreg Kroah-Hartman 11096fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 11196fd7ce5SGreg Kroah-Hartman { 11296fd7ce5SGreg Kroah-Hartman unsigned long flags; 11396fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 11496fd7ce5SGreg Kroah-Hartman 115137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 11696fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 11796fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 11896fd7ce5SGreg Kroah-Hartman if (ldops) { 11996fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 12096fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 12196fd7ce5SGreg Kroah-Hartman ldops->refcount++; 12296fd7ce5SGreg Kroah-Hartman ret = ldops; 12396fd7ce5SGreg Kroah-Hartman } 12496fd7ce5SGreg Kroah-Hartman } 125137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 12696fd7ce5SGreg Kroah-Hartman return ret; 12796fd7ce5SGreg Kroah-Hartman } 12896fd7ce5SGreg Kroah-Hartman 12996fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 13096fd7ce5SGreg Kroah-Hartman { 13196fd7ce5SGreg Kroah-Hartman unsigned long flags; 13296fd7ce5SGreg Kroah-Hartman 133137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 13496fd7ce5SGreg Kroah-Hartman ldops->refcount--; 13596fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 136137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 13796fd7ce5SGreg Kroah-Hartman } 13896fd7ce5SGreg Kroah-Hartman 13996fd7ce5SGreg Kroah-Hartman /** 14096fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 14196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 14296fd7ce5SGreg Kroah-Hartman * 14396fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 144c0cc1c5dSPeter Hurley * module locking counts. 145c0cc1c5dSPeter Hurley * 146c0cc1c5dSPeter Hurley * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or 147c0cc1c5dSPeter Hurley * if the discipline is not registered 148c0cc1c5dSPeter Hurley * -EAGAIN if request_module() failed to load or register the 149c0cc1c5dSPeter Hurley * the discipline 150c0cc1c5dSPeter Hurley * -ENOMEM if allocation failure 151c0cc1c5dSPeter Hurley * 152c0cc1c5dSPeter Hurley * Otherwise, returns a pointer to the discipline and bumps the 153c0cc1c5dSPeter Hurley * ref count 15496fd7ce5SGreg Kroah-Hartman * 15596fd7ce5SGreg Kroah-Hartman * Locking: 156137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 15796fd7ce5SGreg Kroah-Hartman */ 15896fd7ce5SGreg Kroah-Hartman 15936697529SPeter Hurley static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) 16096fd7ce5SGreg Kroah-Hartman { 16196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 16296fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 16396fd7ce5SGreg Kroah-Hartman 16496fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 16596fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 16696fd7ce5SGreg Kroah-Hartman 16796fd7ce5SGreg Kroah-Hartman /* 16896fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 16996fd7ce5SGreg Kroah-Hartman * dynamically and try again. 17096fd7ce5SGreg Kroah-Hartman */ 17196fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 17296fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 17396fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 17496fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 17596fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 17696fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 17796fd7ce5SGreg Kroah-Hartman } 17896fd7ce5SGreg Kroah-Hartman 179bcdd0ca8STetsuo Handa /* 180bcdd0ca8STetsuo Handa * There is no way to handle allocation failure of only 16 bytes. 181bcdd0ca8STetsuo Handa * Let's simplify error handling and save more memory. 182bcdd0ca8STetsuo Handa */ 183bcdd0ca8STetsuo Handa ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL); 18496fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 18536697529SPeter Hurley ld->tty = tty; 1861541f845SIvo Sieben 18796fd7ce5SGreg Kroah-Hartman return ld; 18896fd7ce5SGreg Kroah-Hartman } 18996fd7ce5SGreg Kroah-Hartman 190734de249SPeter Hurley /** 191734de249SPeter Hurley * tty_ldisc_put - release the ldisc 192734de249SPeter Hurley * 193734de249SPeter Hurley * Complement of tty_ldisc_get(). 194734de249SPeter Hurley */ 195cb128f69SDenys Vlasenko static void tty_ldisc_put(struct tty_ldisc *ld) 196734de249SPeter Hurley { 197734de249SPeter Hurley if (WARN_ON_ONCE(!ld)) 198734de249SPeter Hurley return; 199734de249SPeter Hurley 20036697529SPeter Hurley put_ldops(ld->ops); 201734de249SPeter Hurley kfree(ld); 202734de249SPeter Hurley } 203734de249SPeter Hurley 20496fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 20596fd7ce5SGreg Kroah-Hartman { 20696fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 20796fd7ce5SGreg Kroah-Hartman } 20896fd7ce5SGreg Kroah-Hartman 20996fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 21096fd7ce5SGreg Kroah-Hartman { 21196fd7ce5SGreg Kroah-Hartman (*pos)++; 21296fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 21396fd7ce5SGreg Kroah-Hartman } 21496fd7ce5SGreg Kroah-Hartman 21596fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 21696fd7ce5SGreg Kroah-Hartman { 21796fd7ce5SGreg Kroah-Hartman } 21896fd7ce5SGreg Kroah-Hartman 21996fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 22096fd7ce5SGreg Kroah-Hartman { 22196fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 22296fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 22396fd7ce5SGreg Kroah-Hartman 22496fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 22596fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 22696fd7ce5SGreg Kroah-Hartman return 0; 22796fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 22896fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 22996fd7ce5SGreg Kroah-Hartman return 0; 23096fd7ce5SGreg Kroah-Hartman } 23196fd7ce5SGreg Kroah-Hartman 232fddda2b7SChristoph Hellwig const struct seq_operations tty_ldiscs_seq_ops = { 23396fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 23496fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 23596fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 23696fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 23796fd7ce5SGreg Kroah-Hartman }; 23896fd7ce5SGreg Kroah-Hartman 23996fd7ce5SGreg Kroah-Hartman /** 24096fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 24196fd7ce5SGreg Kroah-Hartman * @tty: tty device 24296fd7ce5SGreg Kroah-Hartman * 24396fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 24496fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 24596fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 24696fd7ce5SGreg Kroah-Hartman * 247892d1fa7SPeter Hurley * Returns: NULL if the tty has been hungup and not re-opened with 248892d1fa7SPeter Hurley * a new file descriptor, otherwise valid ldisc reference 249892d1fa7SPeter Hurley * 25096fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 25196fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 25296fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 25396fd7ce5SGreg Kroah-Hartman * (which we check for) 25496fd7ce5SGreg Kroah-Hartman * 255e55afd11SPeter Hurley * Note: a file_operations routine (read/poll/write) should use this 256e55afd11SPeter Hurley * function to wait for any ldisc lifetime events to finish. 25796fd7ce5SGreg Kroah-Hartman */ 25896fd7ce5SGreg Kroah-Hartman 25996fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 26096fd7ce5SGreg Kroah-Hartman { 261a4a3e061SDmitry Vyukov struct tty_ldisc *ld; 262a4a3e061SDmitry Vyukov 26336697529SPeter Hurley ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); 264a4a3e061SDmitry Vyukov ld = tty->ldisc; 265a4a3e061SDmitry Vyukov if (!ld) 266a570a49aSPeter Hurley ldsem_up_read(&tty->ldisc_sem); 267a4a3e061SDmitry Vyukov return ld; 26896fd7ce5SGreg Kroah-Hartman } 26996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 27096fd7ce5SGreg Kroah-Hartman 27196fd7ce5SGreg Kroah-Hartman /** 27296fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 27396fd7ce5SGreg Kroah-Hartman * @tty: tty device 27496fd7ce5SGreg Kroah-Hartman * 27596fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 27696fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 27796fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 27896fd7ce5SGreg Kroah-Hartman */ 27996fd7ce5SGreg Kroah-Hartman 28096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 28196fd7ce5SGreg Kroah-Hartman { 28236697529SPeter Hurley struct tty_ldisc *ld = NULL; 28336697529SPeter Hurley 28436697529SPeter Hurley if (ldsem_down_read_trylock(&tty->ldisc_sem)) { 28536697529SPeter Hurley ld = tty->ldisc; 28636697529SPeter Hurley if (!ld) 28736697529SPeter Hurley ldsem_up_read(&tty->ldisc_sem); 28836697529SPeter Hurley } 28936697529SPeter Hurley return ld; 29096fd7ce5SGreg Kroah-Hartman } 29196fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 29296fd7ce5SGreg Kroah-Hartman 29396fd7ce5SGreg Kroah-Hartman /** 29496fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 29596fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 29696fd7ce5SGreg Kroah-Hartman * 29796fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 29896fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 29996fd7ce5SGreg Kroah-Hartman */ 30096fd7ce5SGreg Kroah-Hartman 30196fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 30296fd7ce5SGreg Kroah-Hartman { 30336697529SPeter Hurley ldsem_up_read(&ld->tty->ldisc_sem); 30496fd7ce5SGreg Kroah-Hartman } 30596fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 30696fd7ce5SGreg Kroah-Hartman 307d2c43890SPeter Hurley 308c2bb524bSPeter Hurley static inline int 309e80a10eeSPeter Hurley __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 310d2c43890SPeter Hurley { 311d2c43890SPeter Hurley return ldsem_down_write(&tty->ldisc_sem, timeout); 312d2c43890SPeter Hurley } 313d2c43890SPeter Hurley 314c2bb524bSPeter Hurley static inline int 315e80a10eeSPeter Hurley __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) 316d2c43890SPeter Hurley { 317d2c43890SPeter Hurley return ldsem_down_write_nested(&tty->ldisc_sem, 318d2c43890SPeter Hurley LDISC_SEM_OTHER, timeout); 319d2c43890SPeter Hurley } 320d2c43890SPeter Hurley 321e80a10eeSPeter Hurley static inline void __tty_ldisc_unlock(struct tty_struct *tty) 322d2c43890SPeter Hurley { 32352772ea6SGuillaume Gomez ldsem_up_write(&tty->ldisc_sem); 324d2c43890SPeter Hurley } 325d2c43890SPeter Hurley 326b027e229SGaurav Kohli int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 327fae76e9aSPeter Hurley { 328fae76e9aSPeter Hurley int ret; 329fae76e9aSPeter Hurley 330fae76e9aSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 331fae76e9aSPeter Hurley if (!ret) 332fae76e9aSPeter Hurley return -EBUSY; 333fae76e9aSPeter Hurley set_bit(TTY_LDISC_HALTED, &tty->flags); 334fae76e9aSPeter Hurley return 0; 335fae76e9aSPeter Hurley } 336fae76e9aSPeter Hurley 337b027e229SGaurav Kohli void tty_ldisc_unlock(struct tty_struct *tty) 338fae76e9aSPeter Hurley { 339fae76e9aSPeter Hurley clear_bit(TTY_LDISC_HALTED, &tty->flags); 340fae76e9aSPeter Hurley __tty_ldisc_unlock(tty); 341fae76e9aSPeter Hurley } 342fae76e9aSPeter Hurley 343c2bb524bSPeter Hurley static int 344d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, 345d2c43890SPeter Hurley unsigned long timeout) 346d2c43890SPeter Hurley { 347d2c43890SPeter Hurley int ret; 348d2c43890SPeter Hurley 349d2c43890SPeter Hurley if (tty < tty2) { 350e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 351d2c43890SPeter Hurley if (ret) { 352e80a10eeSPeter Hurley ret = __tty_ldisc_lock_nested(tty2, timeout); 353d2c43890SPeter Hurley if (!ret) 354e80a10eeSPeter Hurley __tty_ldisc_unlock(tty); 355d2c43890SPeter Hurley } 356d2c43890SPeter Hurley } else { 357d2c43890SPeter Hurley /* if this is possible, it has lots of implications */ 358d2c43890SPeter Hurley WARN_ON_ONCE(tty == tty2); 359d2c43890SPeter Hurley if (tty2 && tty != tty2) { 360e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty2, timeout); 361d2c43890SPeter Hurley if (ret) { 362e80a10eeSPeter Hurley ret = __tty_ldisc_lock_nested(tty, timeout); 363d2c43890SPeter Hurley if (!ret) 364e80a10eeSPeter Hurley __tty_ldisc_unlock(tty2); 365d2c43890SPeter Hurley } 366d2c43890SPeter Hurley } else 367e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 368d2c43890SPeter Hurley } 369d2c43890SPeter Hurley 370d2c43890SPeter Hurley if (!ret) 371d2c43890SPeter Hurley return -EBUSY; 372d2c43890SPeter Hurley 373d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty->flags); 374d2c43890SPeter Hurley if (tty2) 375d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty2->flags); 376d2c43890SPeter Hurley return 0; 377d2c43890SPeter Hurley } 378d2c43890SPeter Hurley 379c2bb524bSPeter Hurley static void tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) 380d2c43890SPeter Hurley { 381d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); 382d2c43890SPeter Hurley } 383d2c43890SPeter Hurley 384c2bb524bSPeter Hurley static void tty_ldisc_unlock_pair(struct tty_struct *tty, 385d2c43890SPeter Hurley struct tty_struct *tty2) 386d2c43890SPeter Hurley { 387e80a10eeSPeter Hurley __tty_ldisc_unlock(tty); 388d2c43890SPeter Hurley if (tty2) 389e80a10eeSPeter Hurley __tty_ldisc_unlock(tty2); 390d2c43890SPeter Hurley } 391d2c43890SPeter Hurley 39296fd7ce5SGreg Kroah-Hartman /** 39396fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 39496fd7ce5SGreg Kroah-Hartman * @tty: tty 39596fd7ce5SGreg Kroah-Hartman * 39686c80a8eSPeter Hurley * Flush the line discipline queue (if any) and the tty flip buffers 39786c80a8eSPeter Hurley * for this tty. 39896fd7ce5SGreg Kroah-Hartman */ 39996fd7ce5SGreg Kroah-Hartman 40096fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 40196fd7ce5SGreg Kroah-Hartman { 40296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 40386c80a8eSPeter Hurley 40486c80a8eSPeter Hurley tty_buffer_flush(tty, ld); 40586c80a8eSPeter Hurley if (ld) 40696fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 40796fd7ce5SGreg Kroah-Hartman } 40896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 40996fd7ce5SGreg Kroah-Hartman 41096fd7ce5SGreg Kroah-Hartman /** 41196fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 41296fd7ce5SGreg Kroah-Hartman * @tty: tty structure 413c12da96fSPeter Hurley * @disc: line discipline number 41496fd7ce5SGreg Kroah-Hartman * 41596fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 41696fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 41796fd7ce5SGreg Kroah-Hartman * any harm. 41896fd7ce5SGreg Kroah-Hartman * 419dd42bf11SPeter Hurley * The line discipline-related tty_struct fields are reset to 420dd42bf11SPeter Hurley * prevent the ldisc driver from re-using stale information for 421dd42bf11SPeter Hurley * the new ldisc instance. 422dd42bf11SPeter Hurley * 4236a1c0680SPeter Hurley * Locking: takes termios_rwsem 42496fd7ce5SGreg Kroah-Hartman */ 42596fd7ce5SGreg Kroah-Hartman 426c12da96fSPeter Hurley static void tty_set_termios_ldisc(struct tty_struct *tty, int disc) 42796fd7ce5SGreg Kroah-Hartman { 4286a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 429c12da96fSPeter Hurley tty->termios.c_line = disc; 4306a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 431dd42bf11SPeter Hurley 432dd42bf11SPeter Hurley tty->disc_data = NULL; 433dd42bf11SPeter Hurley tty->receive_room = 0; 43496fd7ce5SGreg Kroah-Hartman } 43596fd7ce5SGreg Kroah-Hartman 43696fd7ce5SGreg Kroah-Hartman /** 43796fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 43896fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 43996fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 44096fd7ce5SGreg Kroah-Hartman * 44196fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 44296fd7ce5SGreg Kroah-Hartman * point. 44396fd7ce5SGreg Kroah-Hartman * 44496fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 44596fd7ce5SGreg Kroah-Hartman */ 44696fd7ce5SGreg Kroah-Hartman 44796fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 44896fd7ce5SGreg Kroah-Hartman { 44996fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 45096fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 45196fd7ce5SGreg Kroah-Hartman int ret; 45296fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 45396fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4547f90cfc5SJiri Slaby if (ret) 4557f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 456fb6edc91SPeter Hurley 457a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: opened\n", ld); 45896fd7ce5SGreg Kroah-Hartman return ret; 45996fd7ce5SGreg Kroah-Hartman } 46096fd7ce5SGreg Kroah-Hartman return 0; 46196fd7ce5SGreg Kroah-Hartman } 46296fd7ce5SGreg Kroah-Hartman 46396fd7ce5SGreg Kroah-Hartman /** 46496fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 46596fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 46696fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 46796fd7ce5SGreg Kroah-Hartman * 46896fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 46996fd7ce5SGreg Kroah-Hartman * point. 47096fd7ce5SGreg Kroah-Hartman */ 47196fd7ce5SGreg Kroah-Hartman 47296fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 47396fd7ce5SGreg Kroah-Hartman { 47496fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 47596fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 47696fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 47796fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 478a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: closed\n", ld); 47996fd7ce5SGreg Kroah-Hartman } 48096fd7ce5SGreg Kroah-Hartman 48196fd7ce5SGreg Kroah-Hartman /** 4828a8dabf2SAlan Cox * tty_ldisc_failto - helper for ldisc failback 4838a8dabf2SAlan Cox * @tty: tty to open the ldisc on 4848a8dabf2SAlan Cox * @ld: ldisc we are trying to fail back to 4858a8dabf2SAlan Cox * 4868a8dabf2SAlan Cox * Helper to try and recover a tty when switching back to the old 4878a8dabf2SAlan Cox * ldisc fails and we need something attached. 4888a8dabf2SAlan Cox */ 4898a8dabf2SAlan Cox 4908a8dabf2SAlan Cox static int tty_ldisc_failto(struct tty_struct *tty, int ld) 4918a8dabf2SAlan Cox { 4928a8dabf2SAlan Cox struct tty_ldisc *disc = tty_ldisc_get(tty, ld); 4938a8dabf2SAlan Cox int r; 4948a8dabf2SAlan Cox 4958a8dabf2SAlan Cox if (IS_ERR(disc)) 4968a8dabf2SAlan Cox return PTR_ERR(disc); 4978a8dabf2SAlan Cox tty->ldisc = disc; 4988a8dabf2SAlan Cox tty_set_termios_ldisc(tty, ld); 4998a8dabf2SAlan Cox if ((r = tty_ldisc_open(tty, disc)) < 0) 5008a8dabf2SAlan Cox tty_ldisc_put(disc); 5018a8dabf2SAlan Cox return r; 5028a8dabf2SAlan Cox } 5038a8dabf2SAlan Cox 5048a8dabf2SAlan Cox /** 505a8983d01SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 506a8983d01SGreg Kroah-Hartman * @tty: tty to recover 507a8983d01SGreg Kroah-Hartman * @old: previous ldisc 508a8983d01SGreg Kroah-Hartman * 509a8983d01SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 510a8983d01SGreg Kroah-Hartman * change fails due to an open error 511a8983d01SGreg Kroah-Hartman */ 512a8983d01SGreg Kroah-Hartman 513a8983d01SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 514a8983d01SGreg Kroah-Hartman { 515a8983d01SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 516598c2d41STetsuo Handa if (tty_ldisc_failto(tty, old->ops->num) < 0) { 517598c2d41STetsuo Handa const char *name = tty_name(tty); 518598c2d41STetsuo Handa 519598c2d41STetsuo Handa pr_warn("Falling back ldisc for %s.\n", name); 5208a8dabf2SAlan Cox /* The traditional behaviour is to fall back to N_TTY, we 5218a8dabf2SAlan Cox want to avoid falling back to N_NULL unless we have no 5228a8dabf2SAlan Cox choice to avoid the risk of breaking anything */ 5238a8dabf2SAlan Cox if (tty_ldisc_failto(tty, N_TTY) < 0 && 5248a8dabf2SAlan Cox tty_ldisc_failto(tty, N_NULL) < 0) 525598c2d41STetsuo Handa panic("Couldn't open N_NULL ldisc for %s.", name); 526a8983d01SGreg Kroah-Hartman } 527a8983d01SGreg Kroah-Hartman } 528a8983d01SGreg Kroah-Hartman 529a8983d01SGreg Kroah-Hartman /** 53096fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 53196fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 53296fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 53396fd7ce5SGreg Kroah-Hartman * 53496fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 53596fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 53696fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 53796fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 53896fd7ce5SGreg Kroah-Hartman */ 53996fd7ce5SGreg Kroah-Hartman 540c12da96fSPeter Hurley int tty_set_ldisc(struct tty_struct *tty, int disc) 54196fd7ce5SGreg Kroah-Hartman { 542a8983d01SGreg Kroah-Hartman int retval; 543a8983d01SGreg Kroah-Hartman struct tty_ldisc *old_ldisc, *new_ldisc; 544a8983d01SGreg Kroah-Hartman 545a8983d01SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(tty, disc); 546a8983d01SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 547a8983d01SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 54896fd7ce5SGreg Kroah-Hartman 549c8483bc9SPeter Hurley tty_lock(tty); 550276a661aSPeter Hurley retval = tty_ldisc_lock(tty, 5 * HZ); 55163d8cb3fSPeter Hurley if (retval) 55263d8cb3fSPeter Hurley goto err; 55396fd7ce5SGreg Kroah-Hartman 554a570a49aSPeter Hurley if (!tty->ldisc) { 555a570a49aSPeter Hurley retval = -EIO; 556a570a49aSPeter Hurley goto out; 557a570a49aSPeter Hurley } 558a570a49aSPeter Hurley 55963d8cb3fSPeter Hurley /* Check the no-op case */ 560a8983d01SGreg Kroah-Hartman if (tty->ldisc->ops->num == disc) 56163d8cb3fSPeter Hurley goto out; 56296fd7ce5SGreg Kroah-Hartman 56363d8cb3fSPeter Hurley if (test_bit(TTY_HUPPED, &tty->flags)) { 56463d8cb3fSPeter Hurley /* We were raced by hangup */ 56563d8cb3fSPeter Hurley retval = -EIO; 56663d8cb3fSPeter Hurley goto out; 56796fd7ce5SGreg Kroah-Hartman } 56896fd7ce5SGreg Kroah-Hartman 569a8983d01SGreg Kroah-Hartman old_ldisc = tty->ldisc; 570a8983d01SGreg Kroah-Hartman 571a8983d01SGreg Kroah-Hartman /* Shutdown the old discipline. */ 572a8983d01SGreg Kroah-Hartman tty_ldisc_close(tty, old_ldisc); 573a8983d01SGreg Kroah-Hartman 574a8983d01SGreg Kroah-Hartman /* Now set up the new line discipline. */ 575a8983d01SGreg Kroah-Hartman tty->ldisc = new_ldisc; 576a8983d01SGreg Kroah-Hartman tty_set_termios_ldisc(tty, disc); 577a8983d01SGreg Kroah-Hartman 578a8983d01SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 57996fd7ce5SGreg Kroah-Hartman if (retval < 0) { 58096fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 581a8983d01SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 582a8983d01SGreg Kroah-Hartman tty_ldisc_restore(tty, old_ldisc); 58396fd7ce5SGreg Kroah-Hartman } 58496fd7ce5SGreg Kroah-Hartman 585a8983d01SGreg Kroah-Hartman if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) { 5869191aaaaSPeter Hurley down_read(&tty->termios_rwsem); 58796fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 5889191aaaaSPeter Hurley up_read(&tty->termios_rwsem); 5899191aaaaSPeter Hurley } 59096fd7ce5SGreg Kroah-Hartman 591a8983d01SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 592a8983d01SGreg Kroah-Hartman reference to the old ldisc, or we hold two references to 593a8983d01SGreg Kroah-Hartman the old ldisc (if it was restored as part of error cleanup 594a8983d01SGreg Kroah-Hartman above). In either case, releasing a single reference from 595a8983d01SGreg Kroah-Hartman the old ldisc is correct. */ 596a8983d01SGreg Kroah-Hartman new_ldisc = old_ldisc; 59763d8cb3fSPeter Hurley out: 598276a661aSPeter Hurley tty_ldisc_unlock(tty); 59996fd7ce5SGreg Kroah-Hartman 60096fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 60196fd7ce5SGreg Kroah-Hartman already running */ 60217a69219SPeter Hurley tty_buffer_restart_work(tty->port); 60363d8cb3fSPeter Hurley err: 604a8983d01SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); /* drop the extra reference */ 60589c8d91eSAlan Cox tty_unlock(tty); 60696fd7ce5SGreg Kroah-Hartman return retval; 60796fd7ce5SGreg Kroah-Hartman } 6081ab92da3SOkash Khawaja EXPORT_SYMBOL_GPL(tty_set_ldisc); 60996fd7ce5SGreg Kroah-Hartman 61096fd7ce5SGreg Kroah-Hartman /** 6116ffeb4b2SPeter Hurley * tty_ldisc_kill - teardown ldisc 6126ffeb4b2SPeter Hurley * @tty: tty being released 6136ffeb4b2SPeter Hurley * 6146ffeb4b2SPeter Hurley * Perform final close of the ldisc and reset tty->ldisc 6156ffeb4b2SPeter Hurley */ 6166ffeb4b2SPeter Hurley static void tty_ldisc_kill(struct tty_struct *tty) 6176ffeb4b2SPeter Hurley { 6186ffeb4b2SPeter Hurley if (!tty->ldisc) 6196ffeb4b2SPeter Hurley return; 6206ffeb4b2SPeter Hurley /* 6216ffeb4b2SPeter Hurley * Now kill off the ldisc 6226ffeb4b2SPeter Hurley */ 6236ffeb4b2SPeter Hurley tty_ldisc_close(tty, tty->ldisc); 6246ffeb4b2SPeter Hurley tty_ldisc_put(tty->ldisc); 6256ffeb4b2SPeter Hurley /* Force an oops if we mess this up */ 6266ffeb4b2SPeter Hurley tty->ldisc = NULL; 6276ffeb4b2SPeter Hurley } 6286ffeb4b2SPeter Hurley 6296ffeb4b2SPeter Hurley /** 63096fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 63196fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 63296fd7ce5SGreg Kroah-Hartman * 63396fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 63496fd7ce5SGreg Kroah-Hartman */ 63596fd7ce5SGreg Kroah-Hartman 63696fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 63796fd7ce5SGreg Kroah-Hartman { 6386a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 639adc8d746SAlan Cox tty->termios = tty->driver->init_termios; 640adc8d746SAlan Cox tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); 641adc8d746SAlan Cox tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); 6426a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 64396fd7ce5SGreg Kroah-Hartman } 64496fd7ce5SGreg Kroah-Hartman 64596fd7ce5SGreg Kroah-Hartman 64696fd7ce5SGreg Kroah-Hartman /** 64796fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 64896fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 649c12da96fSPeter Hurley * @disc: line discipline to reinitialize 65096fd7ce5SGreg Kroah-Hartman * 6517896f30dSPeter Hurley * Completely reinitialize the line discipline state, by closing the 652892d1fa7SPeter Hurley * current instance, if there is one, and opening a new instance. If 653892d1fa7SPeter Hurley * an error occurs opening the new non-N_TTY instance, the instance 654892d1fa7SPeter Hurley * is dropped and tty->ldisc reset to NULL. The caller can then retry 655892d1fa7SPeter Hurley * with N_TTY instead. 6567896f30dSPeter Hurley * 6577896f30dSPeter Hurley * Returns 0 if successful, otherwise error code < 0 65896fd7ce5SGreg Kroah-Hartman */ 65996fd7ce5SGreg Kroah-Hartman 660892d1fa7SPeter Hurley int tty_ldisc_reinit(struct tty_struct *tty, int disc) 66196fd7ce5SGreg Kroah-Hartman { 6627896f30dSPeter Hurley struct tty_ldisc *ld; 6637896f30dSPeter Hurley int retval; 6641c95ba1eSPhilippe Rétornaz 6657896f30dSPeter Hurley ld = tty_ldisc_get(tty, disc); 666a8983d01SGreg Kroah-Hartman if (IS_ERR(ld)) { 667a8983d01SGreg Kroah-Hartman BUG_ON(disc == N_TTY); 6687896f30dSPeter Hurley return PTR_ERR(ld); 669a8983d01SGreg Kroah-Hartman } 67096fd7ce5SGreg Kroah-Hartman 6717896f30dSPeter Hurley if (tty->ldisc) { 67296fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 67396fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 6747896f30dSPeter Hurley } 6757896f30dSPeter Hurley 6767896f30dSPeter Hurley /* switch the line discipline */ 677f4807045SPeter Hurley tty->ldisc = ld; 678c12da96fSPeter Hurley tty_set_termios_ldisc(tty, disc); 6797896f30dSPeter Hurley retval = tty_ldisc_open(tty, tty->ldisc); 6807896f30dSPeter Hurley if (retval) { 6817896f30dSPeter Hurley tty_ldisc_put(tty->ldisc); 6827896f30dSPeter Hurley tty->ldisc = NULL; 6837896f30dSPeter Hurley } 6847896f30dSPeter Hurley return retval; 68596fd7ce5SGreg Kroah-Hartman } 68696fd7ce5SGreg Kroah-Hartman 68796fd7ce5SGreg Kroah-Hartman /** 68896fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 68996fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 69096fd7ce5SGreg Kroah-Hartman * 69196fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 69296fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 69396fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 69496fd7ce5SGreg Kroah-Hartman * 69596fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 69696fd7ce5SGreg Kroah-Hartman * careful to allow for this. 69796fd7ce5SGreg Kroah-Hartman * 69896fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 69996fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 70096fd7ce5SGreg Kroah-Hartman */ 70196fd7ce5SGreg Kroah-Hartman 702892d1fa7SPeter Hurley void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) 70396fd7ce5SGreg Kroah-Hartman { 70496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 70596fd7ce5SGreg Kroah-Hartman 706a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc); 707fc575ee6SPeter Hurley 70896fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 70996fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 71096fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 71196fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 71296fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 71396fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 71496fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 71596fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 71696fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 71796fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 71896fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 71996fd7ce5SGreg Kroah-Hartman } 72036697529SPeter Hurley 721a9a08845SLinus Torvalds wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT); 722a9a08845SLinus Torvalds wake_up_interruptible_poll(&tty->read_wait, EPOLLIN); 72336697529SPeter Hurley 72496fd7ce5SGreg Kroah-Hartman /* 72596fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 72696fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 72796fd7ce5SGreg Kroah-Hartman * 72896fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 72996fd7ce5SGreg Kroah-Hartman */ 730fae76e9aSPeter Hurley tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); 73196fd7ce5SGreg Kroah-Hartman 732892d1fa7SPeter Hurley if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) 73396fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 734fc575ee6SPeter Hurley 735892d1fa7SPeter Hurley if (tty->ldisc) { 736892d1fa7SPeter Hurley if (reinit) { 737e65c62b1SJohannes Weiner if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0 && 738e65c62b1SJohannes Weiner tty_ldisc_reinit(tty, N_TTY) < 0) 739e65c62b1SJohannes Weiner WARN_ON(tty_ldisc_reinit(tty, N_NULL) < 0); 740892d1fa7SPeter Hurley } else 741892d1fa7SPeter Hurley tty_ldisc_kill(tty); 742892d1fa7SPeter Hurley } 743892d1fa7SPeter Hurley tty_ldisc_unlock(tty); 74496fd7ce5SGreg Kroah-Hartman } 74596fd7ce5SGreg Kroah-Hartman 74696fd7ce5SGreg Kroah-Hartman /** 74796fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 74896fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 74996fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 75096fd7ce5SGreg Kroah-Hartman * 75196fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 75296fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 75396fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 75496fd7ce5SGreg Kroah-Hartman */ 75596fd7ce5SGreg Kroah-Hartman 75696fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 75796fd7ce5SGreg Kroah-Hartman { 7589de2a7ceSPeter Hurley int retval = tty_ldisc_open(tty, tty->ldisc); 75996fd7ce5SGreg Kroah-Hartman if (retval) 76096fd7ce5SGreg Kroah-Hartman return retval; 76196fd7ce5SGreg Kroah-Hartman 76296fd7ce5SGreg Kroah-Hartman if (o_tty) { 76396fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 76496fd7ce5SGreg Kroah-Hartman if (retval) { 7659de2a7ceSPeter Hurley tty_ldisc_close(tty, tty->ldisc); 76696fd7ce5SGreg Kroah-Hartman return retval; 76796fd7ce5SGreg Kroah-Hartman } 76896fd7ce5SGreg Kroah-Hartman } 76996fd7ce5SGreg Kroah-Hartman return 0; 77096fd7ce5SGreg Kroah-Hartman } 77189c8d91eSAlan Cox 77296fd7ce5SGreg Kroah-Hartman /** 77396fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 77462462aefSPeter Hurley * @tty: tty being shut down (or one end of pty pair) 77596fd7ce5SGreg Kroah-Hartman * 77662462aefSPeter Hurley * Called during the final close of a tty or a pty pair in order to shut 7775b6e6832SPeter Hurley * down the line discpline layer. On exit, each tty's ldisc is NULL. 77896fd7ce5SGreg Kroah-Hartman */ 77996fd7ce5SGreg Kroah-Hartman 78062462aefSPeter Hurley void tty_ldisc_release(struct tty_struct *tty) 78196fd7ce5SGreg Kroah-Hartman { 78262462aefSPeter Hurley struct tty_struct *o_tty = tty->link; 78362462aefSPeter Hurley 78496fd7ce5SGreg Kroah-Hartman /* 785a2965b7bSPeter Hurley * Shutdown this line discipline. As this is the final close, 786a2965b7bSPeter Hurley * it does not race with the set_ldisc code path. 78796fd7ce5SGreg Kroah-Hartman */ 78896fd7ce5SGreg Kroah-Hartman 78936697529SPeter Hurley tty_ldisc_lock_pair(tty, o_tty); 79089c8d91eSAlan Cox tty_ldisc_kill(tty); 79189c8d91eSAlan Cox if (o_tty) 79289c8d91eSAlan Cox tty_ldisc_kill(o_tty); 79336697529SPeter Hurley tty_ldisc_unlock_pair(tty, o_tty); 79436697529SPeter Hurley 79596fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 79696fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 797fc575ee6SPeter Hurley 798fb6edc91SPeter Hurley tty_ldisc_debug(tty, "released\n"); 79996fd7ce5SGreg Kroah-Hartman } 8001ab92da3SOkash Khawaja EXPORT_SYMBOL_GPL(tty_ldisc_release); 80196fd7ce5SGreg Kroah-Hartman 80296fd7ce5SGreg Kroah-Hartman /** 80396fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 80496fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 80596fd7ce5SGreg Kroah-Hartman * 80696fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 80796fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 80896fd7ce5SGreg Kroah-Hartman */ 80996fd7ce5SGreg Kroah-Hartman 810903f9db1STetsuo Handa int tty_ldisc_init(struct tty_struct *tty) 81196fd7ce5SGreg Kroah-Hartman { 81236697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); 81396fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 814903f9db1STetsuo Handa return PTR_ERR(ld); 815f4807045SPeter Hurley tty->ldisc = ld; 816903f9db1STetsuo Handa return 0; 81796fd7ce5SGreg Kroah-Hartman } 81896fd7ce5SGreg Kroah-Hartman 8196716671dSJiri Slaby /** 820c8b710b3SPeter Hurley * tty_ldisc_deinit - ldisc cleanup for new tty 8216716671dSJiri Slaby * @tty: tty that was allocated recently 8226716671dSJiri Slaby * 8236716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 8246716671dSJiri Slaby * this call is made. 8256716671dSJiri Slaby */ 8266716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 8276716671dSJiri Slaby { 828c8b710b3SPeter Hurley if (tty->ldisc) 829ebc9baedSPeter Hurley tty_ldisc_put(tty->ldisc); 830f4807045SPeter Hurley tty->ldisc = NULL; 8316716671dSJiri Slaby } 832