196fd7ce5SGreg Kroah-Hartman #include <linux/types.h> 296fd7ce5SGreg Kroah-Hartman #include <linux/errno.h> 38b3ffa17SJiri Slaby #include <linux/kmod.h> 496fd7ce5SGreg Kroah-Hartman #include <linux/sched.h> 596fd7ce5SGreg Kroah-Hartman #include <linux/interrupt.h> 696fd7ce5SGreg Kroah-Hartman #include <linux/tty.h> 796fd7ce5SGreg Kroah-Hartman #include <linux/tty_driver.h> 896fd7ce5SGreg Kroah-Hartman #include <linux/file.h> 996fd7ce5SGreg Kroah-Hartman #include <linux/mm.h> 1096fd7ce5SGreg Kroah-Hartman #include <linux/string.h> 1196fd7ce5SGreg Kroah-Hartman #include <linux/slab.h> 1296fd7ce5SGreg Kroah-Hartman #include <linux/poll.h> 1396fd7ce5SGreg Kroah-Hartman #include <linux/proc_fs.h> 1496fd7ce5SGreg Kroah-Hartman #include <linux/module.h> 1596fd7ce5SGreg Kroah-Hartman #include <linux/device.h> 1696fd7ce5SGreg Kroah-Hartman #include <linux/wait.h> 1796fd7ce5SGreg Kroah-Hartman #include <linux/bitops.h> 1896fd7ce5SGreg Kroah-Hartman #include <linux/seq_file.h> 1996fd7ce5SGreg Kroah-Hartman #include <linux/uaccess.h> 200c73c08eSJiri Slaby #include <linux/ratelimit.h> 2196fd7ce5SGreg Kroah-Hartman 22fc575ee6SPeter Hurley #undef LDISC_DEBUG_HANGUP 23fc575ee6SPeter Hurley 24fc575ee6SPeter Hurley #ifdef LDISC_DEBUG_HANGUP 250a6adc13SPeter Hurley #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) 26fc575ee6SPeter Hurley #else 27fc575ee6SPeter Hurley #define tty_ldisc_debug(tty, f, args...) 28fc575ee6SPeter Hurley #endif 29fc575ee6SPeter Hurley 30d2c43890SPeter Hurley /* lockdep nested classes for tty->ldisc_sem */ 31d2c43890SPeter Hurley enum { 32d2c43890SPeter Hurley LDISC_SEM_NORMAL, 33d2c43890SPeter Hurley LDISC_SEM_OTHER, 34d2c43890SPeter Hurley }; 35d2c43890SPeter Hurley 36d2c43890SPeter Hurley 3796fd7ce5SGreg Kroah-Hartman /* 3896fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 3996fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4096fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4196fd7ce5SGreg Kroah-Hartman */ 4296fd7ce5SGreg Kroah-Hartman 43137084bbSPeter Hurley static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); 4496fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 4596fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 4696fd7ce5SGreg Kroah-Hartman 4796fd7ce5SGreg Kroah-Hartman /** 4896fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 4996fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 5096fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 5196fd7ce5SGreg Kroah-Hartman * 5296fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 5396fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 5496fd7ce5SGreg Kroah-Hartman * from this point onwards. 5596fd7ce5SGreg Kroah-Hartman * 5696fd7ce5SGreg Kroah-Hartman * Locking: 57137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 5896fd7ce5SGreg Kroah-Hartman */ 5996fd7ce5SGreg Kroah-Hartman 6096fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 6196fd7ce5SGreg Kroah-Hartman { 6296fd7ce5SGreg Kroah-Hartman unsigned long flags; 6396fd7ce5SGreg Kroah-Hartman int ret = 0; 6496fd7ce5SGreg Kroah-Hartman 6596fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 6696fd7ce5SGreg Kroah-Hartman return -EINVAL; 6796fd7ce5SGreg Kroah-Hartman 68137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 6996fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 7096fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 7196fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 72137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 7396fd7ce5SGreg Kroah-Hartman 7496fd7ce5SGreg Kroah-Hartman return ret; 7596fd7ce5SGreg Kroah-Hartman } 7696fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 7796fd7ce5SGreg Kroah-Hartman 7896fd7ce5SGreg Kroah-Hartman /** 7996fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 8096fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 8196fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 8296fd7ce5SGreg Kroah-Hartman * 8396fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 8496fd7ce5SGreg Kroah-Hartman * currently in use. 8596fd7ce5SGreg Kroah-Hartman * 8696fd7ce5SGreg Kroah-Hartman * Locking: 87137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 8896fd7ce5SGreg Kroah-Hartman */ 8996fd7ce5SGreg Kroah-Hartman 9096fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 9196fd7ce5SGreg Kroah-Hartman { 9296fd7ce5SGreg Kroah-Hartman unsigned long flags; 9396fd7ce5SGreg Kroah-Hartman int ret = 0; 9496fd7ce5SGreg Kroah-Hartman 9596fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 9696fd7ce5SGreg Kroah-Hartman return -EINVAL; 9796fd7ce5SGreg Kroah-Hartman 98137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 9996fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 10096fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 10196fd7ce5SGreg Kroah-Hartman else 10296fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 103137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 10496fd7ce5SGreg Kroah-Hartman 10596fd7ce5SGreg Kroah-Hartman return ret; 10696fd7ce5SGreg Kroah-Hartman } 10796fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 10896fd7ce5SGreg Kroah-Hartman 10996fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 11096fd7ce5SGreg Kroah-Hartman { 11196fd7ce5SGreg Kroah-Hartman unsigned long flags; 11296fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 11396fd7ce5SGreg Kroah-Hartman 114137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 11596fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 11696fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 11796fd7ce5SGreg Kroah-Hartman if (ldops) { 11896fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 11996fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 12096fd7ce5SGreg Kroah-Hartman ldops->refcount++; 12196fd7ce5SGreg Kroah-Hartman ret = ldops; 12296fd7ce5SGreg Kroah-Hartman } 12396fd7ce5SGreg Kroah-Hartman } 124137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 12596fd7ce5SGreg Kroah-Hartman return ret; 12696fd7ce5SGreg Kroah-Hartman } 12796fd7ce5SGreg Kroah-Hartman 12896fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 12996fd7ce5SGreg Kroah-Hartman { 13096fd7ce5SGreg Kroah-Hartman unsigned long flags; 13196fd7ce5SGreg Kroah-Hartman 132137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 13396fd7ce5SGreg Kroah-Hartman ldops->refcount--; 13496fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 135137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 13696fd7ce5SGreg Kroah-Hartman } 13796fd7ce5SGreg Kroah-Hartman 13896fd7ce5SGreg Kroah-Hartman /** 13996fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 14096fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 14196fd7ce5SGreg Kroah-Hartman * 14296fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 14396fd7ce5SGreg Kroah-Hartman * module locking counts. Returns NULL if the discipline is not available. 14496fd7ce5SGreg Kroah-Hartman * Returns a pointer to the discipline and bumps the ref count if it is 14596fd7ce5SGreg Kroah-Hartman * available 14696fd7ce5SGreg Kroah-Hartman * 14796fd7ce5SGreg Kroah-Hartman * Locking: 148137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 14996fd7ce5SGreg Kroah-Hartman */ 15096fd7ce5SGreg Kroah-Hartman 15136697529SPeter Hurley static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) 15296fd7ce5SGreg Kroah-Hartman { 15396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 15496fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 15596fd7ce5SGreg Kroah-Hartman 15696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 15796fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 15896fd7ce5SGreg Kroah-Hartman 15996fd7ce5SGreg Kroah-Hartman /* 16096fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 16196fd7ce5SGreg Kroah-Hartman * dynamically and try again. 16296fd7ce5SGreg Kroah-Hartman */ 16396fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 16496fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 16596fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 16696fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 16796fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 16896fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 16996fd7ce5SGreg Kroah-Hartman } 17096fd7ce5SGreg Kroah-Hartman 17196fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 17296fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 17396fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 17496fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 17596fd7ce5SGreg Kroah-Hartman } 17696fd7ce5SGreg Kroah-Hartman 17796fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 17836697529SPeter Hurley ld->tty = tty; 1791541f845SIvo Sieben 18096fd7ce5SGreg Kroah-Hartman return ld; 18196fd7ce5SGreg Kroah-Hartman } 18296fd7ce5SGreg Kroah-Hartman 183734de249SPeter Hurley /** 184734de249SPeter Hurley * tty_ldisc_put - release the ldisc 185734de249SPeter Hurley * 186734de249SPeter Hurley * Complement of tty_ldisc_get(). 187734de249SPeter Hurley */ 188734de249SPeter Hurley static inline void tty_ldisc_put(struct tty_ldisc *ld) 189734de249SPeter Hurley { 190734de249SPeter Hurley if (WARN_ON_ONCE(!ld)) 191734de249SPeter Hurley return; 192734de249SPeter Hurley 19336697529SPeter Hurley put_ldops(ld->ops); 194734de249SPeter Hurley kfree(ld); 195734de249SPeter Hurley } 196734de249SPeter Hurley 19796fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 19896fd7ce5SGreg Kroah-Hartman { 19996fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 20096fd7ce5SGreg Kroah-Hartman } 20196fd7ce5SGreg Kroah-Hartman 20296fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 20396fd7ce5SGreg Kroah-Hartman { 20496fd7ce5SGreg Kroah-Hartman (*pos)++; 20596fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 20696fd7ce5SGreg Kroah-Hartman } 20796fd7ce5SGreg Kroah-Hartman 20896fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 20996fd7ce5SGreg Kroah-Hartman { 21096fd7ce5SGreg Kroah-Hartman } 21196fd7ce5SGreg Kroah-Hartman 21296fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 21396fd7ce5SGreg Kroah-Hartman { 21496fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 21596fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 21696fd7ce5SGreg Kroah-Hartman 21796fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 21896fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 21996fd7ce5SGreg Kroah-Hartman return 0; 22096fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 22196fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 22296fd7ce5SGreg Kroah-Hartman return 0; 22396fd7ce5SGreg Kroah-Hartman } 22496fd7ce5SGreg Kroah-Hartman 22596fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 22696fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 22796fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 22896fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 22996fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 23096fd7ce5SGreg Kroah-Hartman }; 23196fd7ce5SGreg Kroah-Hartman 23296fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 23396fd7ce5SGreg Kroah-Hartman { 23496fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 23596fd7ce5SGreg Kroah-Hartman } 23696fd7ce5SGreg Kroah-Hartman 23796fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 23896fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 23996fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 24096fd7ce5SGreg Kroah-Hartman .read = seq_read, 24196fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 24296fd7ce5SGreg Kroah-Hartman .release = seq_release, 24396fd7ce5SGreg Kroah-Hartman }; 24496fd7ce5SGreg Kroah-Hartman 24596fd7ce5SGreg Kroah-Hartman /** 24696fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 24796fd7ce5SGreg Kroah-Hartman * @tty: tty device 24896fd7ce5SGreg Kroah-Hartman * 24996fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 25096fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 25196fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 25296fd7ce5SGreg Kroah-Hartman * 25396fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 25496fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 25596fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 25696fd7ce5SGreg Kroah-Hartman * (which we check for) 25796fd7ce5SGreg Kroah-Hartman * 25836697529SPeter Hurley * Note: only callable from a file_operations routine (which 25936697529SPeter Hurley * guarantees tty->ldisc != NULL when the lock is acquired). 26096fd7ce5SGreg Kroah-Hartman */ 26196fd7ce5SGreg Kroah-Hartman 26296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 26396fd7ce5SGreg Kroah-Hartman { 26436697529SPeter Hurley ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); 26536697529SPeter Hurley WARN_ON(!tty->ldisc); 26636697529SPeter Hurley return tty->ldisc; 26796fd7ce5SGreg Kroah-Hartman } 26896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 26996fd7ce5SGreg Kroah-Hartman 27096fd7ce5SGreg Kroah-Hartman /** 27196fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 27296fd7ce5SGreg Kroah-Hartman * @tty: tty device 27396fd7ce5SGreg Kroah-Hartman * 27496fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 27596fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 27696fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 27796fd7ce5SGreg Kroah-Hartman */ 27896fd7ce5SGreg Kroah-Hartman 27996fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 28096fd7ce5SGreg Kroah-Hartman { 28136697529SPeter Hurley struct tty_ldisc *ld = NULL; 28236697529SPeter Hurley 28336697529SPeter Hurley if (ldsem_down_read_trylock(&tty->ldisc_sem)) { 28436697529SPeter Hurley ld = tty->ldisc; 28536697529SPeter Hurley if (!ld) 28636697529SPeter Hurley ldsem_up_read(&tty->ldisc_sem); 28736697529SPeter Hurley } 28836697529SPeter Hurley return ld; 28996fd7ce5SGreg Kroah-Hartman } 29096fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 29196fd7ce5SGreg Kroah-Hartman 29296fd7ce5SGreg Kroah-Hartman /** 29396fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 29496fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 29596fd7ce5SGreg Kroah-Hartman * 29696fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 29796fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 29896fd7ce5SGreg Kroah-Hartman */ 29996fd7ce5SGreg Kroah-Hartman 30096fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 30196fd7ce5SGreg Kroah-Hartman { 30236697529SPeter Hurley ldsem_up_read(&ld->tty->ldisc_sem); 30396fd7ce5SGreg Kroah-Hartman } 30496fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 30596fd7ce5SGreg Kroah-Hartman 306d2c43890SPeter Hurley 307d2c43890SPeter Hurley static inline int __lockfunc 308e80a10eeSPeter Hurley __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 309d2c43890SPeter Hurley { 310d2c43890SPeter Hurley return ldsem_down_write(&tty->ldisc_sem, timeout); 311d2c43890SPeter Hurley } 312d2c43890SPeter Hurley 313d2c43890SPeter Hurley static inline int __lockfunc 314e80a10eeSPeter Hurley __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) 315d2c43890SPeter Hurley { 316d2c43890SPeter Hurley return ldsem_down_write_nested(&tty->ldisc_sem, 317d2c43890SPeter Hurley LDISC_SEM_OTHER, timeout); 318d2c43890SPeter Hurley } 319d2c43890SPeter Hurley 320e80a10eeSPeter Hurley static inline void __tty_ldisc_unlock(struct tty_struct *tty) 321d2c43890SPeter Hurley { 32252772ea6SGuillaume Gomez ldsem_up_write(&tty->ldisc_sem); 323d2c43890SPeter Hurley } 324d2c43890SPeter Hurley 325d2c43890SPeter Hurley static int __lockfunc 326fae76e9aSPeter Hurley 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 337fae76e9aSPeter Hurley static 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 343fae76e9aSPeter Hurley static int __lockfunc 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 379d2c43890SPeter Hurley static void __lockfunc 380d2c43890SPeter Hurley tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) 381d2c43890SPeter Hurley { 382d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); 383d2c43890SPeter Hurley } 384d2c43890SPeter Hurley 385d2c43890SPeter Hurley static void __lockfunc tty_ldisc_unlock_pair(struct tty_struct *tty, 386d2c43890SPeter Hurley struct tty_struct *tty2) 387d2c43890SPeter Hurley { 388e80a10eeSPeter Hurley __tty_ldisc_unlock(tty); 389d2c43890SPeter Hurley if (tty2) 390e80a10eeSPeter Hurley __tty_ldisc_unlock(tty2); 391d2c43890SPeter Hurley } 392d2c43890SPeter Hurley 39396fd7ce5SGreg Kroah-Hartman /** 39496fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 39596fd7ce5SGreg Kroah-Hartman * @tty: tty 39696fd7ce5SGreg Kroah-Hartman * 39786c80a8eSPeter Hurley * Flush the line discipline queue (if any) and the tty flip buffers 39886c80a8eSPeter Hurley * for this tty. 39996fd7ce5SGreg Kroah-Hartman */ 40096fd7ce5SGreg Kroah-Hartman 40196fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 40296fd7ce5SGreg Kroah-Hartman { 40396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 40486c80a8eSPeter Hurley 40586c80a8eSPeter Hurley tty_buffer_flush(tty, ld); 40686c80a8eSPeter Hurley if (ld) 40796fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 40896fd7ce5SGreg Kroah-Hartman } 40996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 41096fd7ce5SGreg Kroah-Hartman 41196fd7ce5SGreg Kroah-Hartman /** 41296fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 41396fd7ce5SGreg Kroah-Hartman * @tty: tty structure 41496fd7ce5SGreg Kroah-Hartman * @num: line discipline number 41596fd7ce5SGreg Kroah-Hartman * 41696fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 41796fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 41896fd7ce5SGreg Kroah-Hartman * any harm. 41996fd7ce5SGreg Kroah-Hartman * 4206a1c0680SPeter Hurley * Locking: takes termios_rwsem 42196fd7ce5SGreg Kroah-Hartman */ 42296fd7ce5SGreg Kroah-Hartman 42396fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 42496fd7ce5SGreg Kroah-Hartman { 4256a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 426adc8d746SAlan Cox tty->termios.c_line = num; 4276a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 42896fd7ce5SGreg Kroah-Hartman } 42996fd7ce5SGreg Kroah-Hartman 43096fd7ce5SGreg Kroah-Hartman /** 43196fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 43296fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 43396fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 43496fd7ce5SGreg Kroah-Hartman * 43596fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 43696fd7ce5SGreg Kroah-Hartman * point. 43796fd7ce5SGreg Kroah-Hartman * 43896fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 43996fd7ce5SGreg Kroah-Hartman */ 44096fd7ce5SGreg Kroah-Hartman 44196fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 44296fd7ce5SGreg Kroah-Hartman { 44396fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 44496fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 44596fd7ce5SGreg Kroah-Hartman int ret; 44696fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 44796fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4487f90cfc5SJiri Slaby if (ret) 4497f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 450fb6edc91SPeter Hurley 451fb6edc91SPeter Hurley tty_ldisc_debug(tty, "%p: opened\n", tty->ldisc); 45296fd7ce5SGreg Kroah-Hartman return ret; 45396fd7ce5SGreg Kroah-Hartman } 45496fd7ce5SGreg Kroah-Hartman return 0; 45596fd7ce5SGreg Kroah-Hartman } 45696fd7ce5SGreg Kroah-Hartman 45796fd7ce5SGreg Kroah-Hartman /** 45896fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 45996fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 46096fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 46196fd7ce5SGreg Kroah-Hartman * 46296fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 46396fd7ce5SGreg Kroah-Hartman * point. 46496fd7ce5SGreg Kroah-Hartman */ 46596fd7ce5SGreg Kroah-Hartman 46696fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 46796fd7ce5SGreg Kroah-Hartman { 46896fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 46996fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 47096fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 47196fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 472fb6edc91SPeter Hurley tty_ldisc_debug(tty, "%p: closed\n", tty->ldisc); 47396fd7ce5SGreg Kroah-Hartman } 47496fd7ce5SGreg Kroah-Hartman 47596fd7ce5SGreg Kroah-Hartman /** 47696fd7ce5SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 47796fd7ce5SGreg Kroah-Hartman * @tty: tty to recover 47896fd7ce5SGreg Kroah-Hartman * @old: previous ldisc 47996fd7ce5SGreg Kroah-Hartman * 48096fd7ce5SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 48196fd7ce5SGreg Kroah-Hartman * change fails due to an open error 48296fd7ce5SGreg Kroah-Hartman */ 48396fd7ce5SGreg Kroah-Hartman 48496fd7ce5SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 48596fd7ce5SGreg Kroah-Hartman { 48696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *new_ldisc; 48796fd7ce5SGreg Kroah-Hartman int r; 48896fd7ce5SGreg Kroah-Hartman 48996fd7ce5SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 49036697529SPeter Hurley old = tty_ldisc_get(tty, old->ops->num); 49196fd7ce5SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 492f4807045SPeter Hurley tty->ldisc = old; 49396fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 49496fd7ce5SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 49596fd7ce5SGreg Kroah-Hartman tty_ldisc_put(old); 49696fd7ce5SGreg Kroah-Hartman /* This driver is always present */ 49736697529SPeter Hurley new_ldisc = tty_ldisc_get(tty, N_TTY); 49896fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 49996fd7ce5SGreg Kroah-Hartman panic("n_tty: get"); 500f4807045SPeter Hurley tty->ldisc = new_ldisc; 50196fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 50296fd7ce5SGreg Kroah-Hartman r = tty_ldisc_open(tty, new_ldisc); 50396fd7ce5SGreg Kroah-Hartman if (r < 0) 50496fd7ce5SGreg Kroah-Hartman panic("Couldn't open N_TTY ldisc for " 50596fd7ce5SGreg Kroah-Hartman "%s --- error %d.", 506429b4749SRasmus Villemoes tty_name(tty), r); 50796fd7ce5SGreg Kroah-Hartman } 50896fd7ce5SGreg Kroah-Hartman } 50996fd7ce5SGreg Kroah-Hartman 51096fd7ce5SGreg Kroah-Hartman /** 51196fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 51296fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 51396fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 51496fd7ce5SGreg Kroah-Hartman * 51596fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 51696fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 51796fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 51896fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 51996fd7ce5SGreg Kroah-Hartman */ 52096fd7ce5SGreg Kroah-Hartman 52196fd7ce5SGreg Kroah-Hartman int tty_set_ldisc(struct tty_struct *tty, int ldisc) 52296fd7ce5SGreg Kroah-Hartman { 52396fd7ce5SGreg Kroah-Hartman int retval; 5249fbfa34cSPeter Hurley struct tty_ldisc *old_ldisc, *new_ldisc; 52596fd7ce5SGreg Kroah-Hartman 52636697529SPeter Hurley new_ldisc = tty_ldisc_get(tty, ldisc); 52796fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 52896fd7ce5SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 52996fd7ce5SGreg Kroah-Hartman 530c8483bc9SPeter Hurley tty_lock(tty); 531276a661aSPeter Hurley retval = tty_ldisc_lock(tty, 5 * HZ); 53236697529SPeter Hurley if (retval) { 53336697529SPeter Hurley tty_ldisc_put(new_ldisc); 534c8483bc9SPeter Hurley tty_unlock(tty); 53536697529SPeter Hurley return retval; 53636697529SPeter Hurley } 53796fd7ce5SGreg Kroah-Hartman 53896fd7ce5SGreg Kroah-Hartman /* 53996fd7ce5SGreg Kroah-Hartman * Check the no-op case 54096fd7ce5SGreg Kroah-Hartman */ 54196fd7ce5SGreg Kroah-Hartman 54296fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num == ldisc) { 543276a661aSPeter Hurley tty_ldisc_unlock(tty); 54496fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 545c8483bc9SPeter Hurley tty_unlock(tty); 54696fd7ce5SGreg Kroah-Hartman return 0; 54796fd7ce5SGreg Kroah-Hartman } 54896fd7ce5SGreg Kroah-Hartman 5499fbfa34cSPeter Hurley old_ldisc = tty->ldisc; 550100eeae2SJiri Slaby 5513ff51a19SPeter Hurley if (test_bit(TTY_HUPPED, &tty->flags)) { 55296fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 55396fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 554276a661aSPeter Hurley tty_ldisc_unlock(tty); 55596fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 55689c8d91eSAlan Cox tty_unlock(tty); 55796fd7ce5SGreg Kroah-Hartman return -EIO; 55896fd7ce5SGreg Kroah-Hartman } 55996fd7ce5SGreg Kroah-Hartman 5609fbfa34cSPeter Hurley /* Shutdown the old discipline. */ 5619fbfa34cSPeter Hurley tty_ldisc_close(tty, old_ldisc); 56296fd7ce5SGreg Kroah-Hartman 56396fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 564f4807045SPeter Hurley tty->ldisc = new_ldisc; 56596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 56696fd7ce5SGreg Kroah-Hartman 56796fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 56896fd7ce5SGreg Kroah-Hartman if (retval < 0) { 56996fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 57096fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 5719fbfa34cSPeter Hurley tty_ldisc_restore(tty, old_ldisc); 57296fd7ce5SGreg Kroah-Hartman } 57396fd7ce5SGreg Kroah-Hartman 5749191aaaaSPeter Hurley if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) { 5759191aaaaSPeter Hurley down_read(&tty->termios_rwsem); 57696fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 5779191aaaaSPeter Hurley up_read(&tty->termios_rwsem); 5789191aaaaSPeter Hurley } 57996fd7ce5SGreg Kroah-Hartman 580b0e95858SPeter Hurley /* At this point we hold a reference to the new ldisc and a 581b0e95858SPeter Hurley reference to the old ldisc, or we hold two references to 582b0e95858SPeter Hurley the old ldisc (if it was restored as part of error cleanup 583b0e95858SPeter Hurley above). In either case, releasing a single reference from 584b0e95858SPeter Hurley the old ldisc is correct. */ 585b0e95858SPeter Hurley 5869fbfa34cSPeter Hurley tty_ldisc_put(old_ldisc); 58796fd7ce5SGreg Kroah-Hartman 58896fd7ce5SGreg Kroah-Hartman /* 58996fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 59096fd7ce5SGreg Kroah-Hartman */ 591276a661aSPeter Hurley tty_ldisc_unlock(tty); 59296fd7ce5SGreg Kroah-Hartman 59396fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 59496fd7ce5SGreg Kroah-Hartman already running */ 595ecbbfd44SJiri Slaby schedule_work(&tty->port->buf.work); 5964f98d467SPeter Hurley 59789c8d91eSAlan Cox tty_unlock(tty); 59896fd7ce5SGreg Kroah-Hartman return retval; 59996fd7ce5SGreg Kroah-Hartman } 60096fd7ce5SGreg Kroah-Hartman 60196fd7ce5SGreg Kroah-Hartman /** 60296fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 60396fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 60496fd7ce5SGreg Kroah-Hartman * 60596fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 60696fd7ce5SGreg Kroah-Hartman */ 60796fd7ce5SGreg Kroah-Hartman 60896fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 60996fd7ce5SGreg Kroah-Hartman { 6106a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 611adc8d746SAlan Cox tty->termios = tty->driver->init_termios; 612adc8d746SAlan Cox tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); 613adc8d746SAlan Cox tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); 6146a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 61596fd7ce5SGreg Kroah-Hartman } 61696fd7ce5SGreg Kroah-Hartman 61796fd7ce5SGreg Kroah-Hartman 61896fd7ce5SGreg Kroah-Hartman /** 61996fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 62096fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 62196fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 62296fd7ce5SGreg Kroah-Hartman * 62396fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 62496fd7ce5SGreg Kroah-Hartman * state closed 62596fd7ce5SGreg Kroah-Hartman */ 62696fd7ce5SGreg Kroah-Hartman 6271c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 62896fd7ce5SGreg Kroah-Hartman { 62936697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, ldisc); 6301c95ba1eSPhilippe Rétornaz 6311c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 6321c95ba1eSPhilippe Rétornaz return -1; 63396fd7ce5SGreg Kroah-Hartman 63496fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 63596fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 63696fd7ce5SGreg Kroah-Hartman /* 63796fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 63896fd7ce5SGreg Kroah-Hartman */ 639f4807045SPeter Hurley tty->ldisc = ld; 64096fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 6411c95ba1eSPhilippe Rétornaz 6421c95ba1eSPhilippe Rétornaz return 0; 64396fd7ce5SGreg Kroah-Hartman } 64496fd7ce5SGreg Kroah-Hartman 64596fd7ce5SGreg Kroah-Hartman /** 64696fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 64796fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 64896fd7ce5SGreg Kroah-Hartman * 64996fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 65096fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 65196fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 65296fd7ce5SGreg Kroah-Hartman * 65396fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 65496fd7ce5SGreg Kroah-Hartman * careful to allow for this. 65596fd7ce5SGreg Kroah-Hartman * 65696fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 65796fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 65896fd7ce5SGreg Kroah-Hartman */ 65996fd7ce5SGreg Kroah-Hartman 66096fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 66196fd7ce5SGreg Kroah-Hartman { 66296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 66396fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 66496fd7ce5SGreg Kroah-Hartman int err = 0; 66596fd7ce5SGreg Kroah-Hartman 666fb6edc91SPeter Hurley tty_ldisc_debug(tty, "%p: closing\n", tty->ldisc); 667fc575ee6SPeter Hurley 66896fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 66996fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 67096fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 67196fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 67296fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 67396fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 67496fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 67596fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 67696fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 67796fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 67896fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 67996fd7ce5SGreg Kroah-Hartman } 68036697529SPeter Hurley 68196fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 68296fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 68336697529SPeter Hurley 68496fd7ce5SGreg Kroah-Hartman /* 68596fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 68696fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 68796fd7ce5SGreg Kroah-Hartman * 68896fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 68996fd7ce5SGreg Kroah-Hartman */ 690fae76e9aSPeter Hurley tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); 69196fd7ce5SGreg Kroah-Hartman 69236697529SPeter Hurley if (tty->ldisc) { 693c8785241SPeter Hurley 694c8785241SPeter Hurley /* At this point we have a halted ldisc; we want to close it and 695c8785241SPeter Hurley reopen a new ldisc. We could defer the reopen to the next 696c8785241SPeter Hurley open but it means auditing a lot of other paths so this is 697c8785241SPeter Hurley a FIXME */ 69896fd7ce5SGreg Kroah-Hartman if (reset == 0) { 6991c95ba1eSPhilippe Rétornaz 700adc8d746SAlan Cox if (!tty_ldisc_reinit(tty, tty->termios.c_line)) 70196fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 7021c95ba1eSPhilippe Rétornaz else 7031c95ba1eSPhilippe Rétornaz err = 1; 70496fd7ce5SGreg Kroah-Hartman } 70596fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 70696fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 70796fd7ce5SGreg Kroah-Hartman if (reset || err) { 7081c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 70996fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 71096fd7ce5SGreg Kroah-Hartman } 71196fd7ce5SGreg Kroah-Hartman } 712fae76e9aSPeter Hurley tty_ldisc_unlock(tty); 71396fd7ce5SGreg Kroah-Hartman if (reset) 71496fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 715fc575ee6SPeter Hurley 716fb6edc91SPeter Hurley tty_ldisc_debug(tty, "%p: re-opened\n", tty->ldisc); 71796fd7ce5SGreg Kroah-Hartman } 71896fd7ce5SGreg Kroah-Hartman 71996fd7ce5SGreg Kroah-Hartman /** 72096fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 72196fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 72296fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 72396fd7ce5SGreg Kroah-Hartman * 72496fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 72596fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 72696fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 72796fd7ce5SGreg Kroah-Hartman */ 72896fd7ce5SGreg Kroah-Hartman 72996fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 73096fd7ce5SGreg Kroah-Hartman { 73196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 73296fd7ce5SGreg Kroah-Hartman int retval; 73396fd7ce5SGreg Kroah-Hartman 73496fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 73596fd7ce5SGreg Kroah-Hartman if (retval) 73696fd7ce5SGreg Kroah-Hartman return retval; 73796fd7ce5SGreg Kroah-Hartman 73896fd7ce5SGreg Kroah-Hartman if (o_tty) { 73996fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 74096fd7ce5SGreg Kroah-Hartman if (retval) { 74196fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 74296fd7ce5SGreg Kroah-Hartman return retval; 74396fd7ce5SGreg Kroah-Hartman } 74496fd7ce5SGreg Kroah-Hartman } 74596fd7ce5SGreg Kroah-Hartman return 0; 74696fd7ce5SGreg Kroah-Hartman } 74789c8d91eSAlan Cox 74889c8d91eSAlan Cox static void tty_ldisc_kill(struct tty_struct *tty) 74989c8d91eSAlan Cox { 75089c8d91eSAlan Cox /* 75189c8d91eSAlan Cox * Now kill off the ldisc 75289c8d91eSAlan Cox */ 75389c8d91eSAlan Cox tty_ldisc_close(tty, tty->ldisc); 75489c8d91eSAlan Cox tty_ldisc_put(tty->ldisc); 75589c8d91eSAlan Cox /* Force an oops if we mess this up */ 75689c8d91eSAlan Cox tty->ldisc = NULL; 75789c8d91eSAlan Cox 75889c8d91eSAlan Cox /* Ensure the next open requests the N_TTY ldisc */ 75989c8d91eSAlan Cox tty_set_termios_ldisc(tty, N_TTY); 76089c8d91eSAlan Cox } 76189c8d91eSAlan Cox 76296fd7ce5SGreg Kroah-Hartman /** 76396fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 76462462aefSPeter Hurley * @tty: tty being shut down (or one end of pty pair) 76596fd7ce5SGreg Kroah-Hartman * 76662462aefSPeter Hurley * Called during the final close of a tty or a pty pair in order to shut 76762462aefSPeter Hurley * down the line discpline layer. On exit, each ldisc assigned is N_TTY and 76862462aefSPeter Hurley * each ldisc has not been opened. 76996fd7ce5SGreg Kroah-Hartman */ 77096fd7ce5SGreg Kroah-Hartman 77162462aefSPeter Hurley void tty_ldisc_release(struct tty_struct *tty) 77296fd7ce5SGreg Kroah-Hartman { 77362462aefSPeter Hurley struct tty_struct *o_tty = tty->link; 77462462aefSPeter Hurley 77596fd7ce5SGreg Kroah-Hartman /* 776a2965b7bSPeter Hurley * Shutdown this line discipline. As this is the final close, 777a2965b7bSPeter Hurley * it does not race with the set_ldisc code path. 77896fd7ce5SGreg Kroah-Hartman */ 77996fd7ce5SGreg Kroah-Hartman 78036697529SPeter Hurley tty_ldisc_lock_pair(tty, o_tty); 78189c8d91eSAlan Cox tty_ldisc_kill(tty); 78289c8d91eSAlan Cox if (o_tty) 78389c8d91eSAlan Cox tty_ldisc_kill(o_tty); 78436697529SPeter Hurley tty_ldisc_unlock_pair(tty, o_tty); 78536697529SPeter Hurley 78696fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 78796fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 788fc575ee6SPeter Hurley 789fb6edc91SPeter Hurley tty_ldisc_debug(tty, "released\n"); 79096fd7ce5SGreg Kroah-Hartman } 79196fd7ce5SGreg Kroah-Hartman 79296fd7ce5SGreg Kroah-Hartman /** 79396fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 79496fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 79596fd7ce5SGreg Kroah-Hartman * 79696fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 79796fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 79896fd7ce5SGreg Kroah-Hartman */ 79996fd7ce5SGreg Kroah-Hartman 80096fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 80196fd7ce5SGreg Kroah-Hartman { 80236697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); 80396fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 80496fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 805f4807045SPeter Hurley tty->ldisc = ld; 80696fd7ce5SGreg Kroah-Hartman } 80796fd7ce5SGreg Kroah-Hartman 8086716671dSJiri Slaby /** 8096716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 8106716671dSJiri Slaby * @tty: tty that was allocated recently 8116716671dSJiri Slaby * 8126716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 8136716671dSJiri Slaby * this call is made. 8146716671dSJiri Slaby */ 8156716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 8166716671dSJiri Slaby { 817ebc9baedSPeter Hurley tty_ldisc_put(tty->ldisc); 818f4807045SPeter Hurley tty->ldisc = NULL; 8196716671dSJiri Slaby } 8206716671dSJiri Slaby 82196fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 82296fd7ce5SGreg Kroah-Hartman { 82396fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 82496fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 82596fd7ce5SGreg Kroah-Hartman } 826