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/init.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 26fc575ee6SPeter Hurley #define tty_ldisc_debug(tty, f, args...) ({ \ 27fc575ee6SPeter Hurley char __b[64]; \ 28fc575ee6SPeter Hurley printk(KERN_DEBUG "%s: %s: " f, __func__, tty_name(tty, __b), ##args); \ 29fc575ee6SPeter Hurley }) 30fc575ee6SPeter Hurley #else 31fc575ee6SPeter Hurley #define tty_ldisc_debug(tty, f, args...) 32fc575ee6SPeter Hurley #endif 33fc575ee6SPeter Hurley 34d2c43890SPeter Hurley /* lockdep nested classes for tty->ldisc_sem */ 35d2c43890SPeter Hurley enum { 36d2c43890SPeter Hurley LDISC_SEM_NORMAL, 37d2c43890SPeter Hurley LDISC_SEM_OTHER, 38d2c43890SPeter Hurley }; 39d2c43890SPeter Hurley 40d2c43890SPeter Hurley 4196fd7ce5SGreg Kroah-Hartman /* 4296fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 4396fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4496fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4596fd7ce5SGreg Kroah-Hartman */ 4696fd7ce5SGreg Kroah-Hartman 47137084bbSPeter Hurley static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); 4896fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 4996fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 5096fd7ce5SGreg Kroah-Hartman 5196fd7ce5SGreg Kroah-Hartman /** 5296fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 5396fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 5496fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 5596fd7ce5SGreg Kroah-Hartman * 5696fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 5796fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 5896fd7ce5SGreg Kroah-Hartman * from this point onwards. 5996fd7ce5SGreg Kroah-Hartman * 6096fd7ce5SGreg Kroah-Hartman * Locking: 61137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 6296fd7ce5SGreg Kroah-Hartman */ 6396fd7ce5SGreg Kroah-Hartman 6496fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 6596fd7ce5SGreg Kroah-Hartman { 6696fd7ce5SGreg Kroah-Hartman unsigned long flags; 6796fd7ce5SGreg Kroah-Hartman int ret = 0; 6896fd7ce5SGreg Kroah-Hartman 6996fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 7096fd7ce5SGreg Kroah-Hartman return -EINVAL; 7196fd7ce5SGreg Kroah-Hartman 72137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 7396fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 7496fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 7596fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 76137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 7796fd7ce5SGreg Kroah-Hartman 7896fd7ce5SGreg Kroah-Hartman return ret; 7996fd7ce5SGreg Kroah-Hartman } 8096fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 8196fd7ce5SGreg Kroah-Hartman 8296fd7ce5SGreg Kroah-Hartman /** 8396fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 8496fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 8596fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 8696fd7ce5SGreg Kroah-Hartman * 8796fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 8896fd7ce5SGreg Kroah-Hartman * currently in use. 8996fd7ce5SGreg Kroah-Hartman * 9096fd7ce5SGreg Kroah-Hartman * Locking: 91137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 9296fd7ce5SGreg Kroah-Hartman */ 9396fd7ce5SGreg Kroah-Hartman 9496fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 9596fd7ce5SGreg Kroah-Hartman { 9696fd7ce5SGreg Kroah-Hartman unsigned long flags; 9796fd7ce5SGreg Kroah-Hartman int ret = 0; 9896fd7ce5SGreg Kroah-Hartman 9996fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 10096fd7ce5SGreg Kroah-Hartman return -EINVAL; 10196fd7ce5SGreg Kroah-Hartman 102137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 10396fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 10496fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 10596fd7ce5SGreg Kroah-Hartman else 10696fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 107137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 10896fd7ce5SGreg Kroah-Hartman 10996fd7ce5SGreg Kroah-Hartman return ret; 11096fd7ce5SGreg Kroah-Hartman } 11196fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 11296fd7ce5SGreg Kroah-Hartman 11396fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 11496fd7ce5SGreg Kroah-Hartman { 11596fd7ce5SGreg Kroah-Hartman unsigned long flags; 11696fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 11796fd7ce5SGreg Kroah-Hartman 118137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 11996fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 12096fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 12196fd7ce5SGreg Kroah-Hartman if (ldops) { 12296fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 12396fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 12496fd7ce5SGreg Kroah-Hartman ldops->refcount++; 12596fd7ce5SGreg Kroah-Hartman ret = ldops; 12696fd7ce5SGreg Kroah-Hartman } 12796fd7ce5SGreg Kroah-Hartman } 128137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 12996fd7ce5SGreg Kroah-Hartman return ret; 13096fd7ce5SGreg Kroah-Hartman } 13196fd7ce5SGreg Kroah-Hartman 13296fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 13396fd7ce5SGreg Kroah-Hartman { 13496fd7ce5SGreg Kroah-Hartman unsigned long flags; 13596fd7ce5SGreg Kroah-Hartman 136137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 13796fd7ce5SGreg Kroah-Hartman ldops->refcount--; 13896fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 139137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 14096fd7ce5SGreg Kroah-Hartman } 14196fd7ce5SGreg Kroah-Hartman 14296fd7ce5SGreg Kroah-Hartman /** 14396fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 14496fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 14596fd7ce5SGreg Kroah-Hartman * 14696fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 14796fd7ce5SGreg Kroah-Hartman * module locking counts. Returns NULL if the discipline is not available. 14896fd7ce5SGreg Kroah-Hartman * Returns a pointer to the discipline and bumps the ref count if it is 14996fd7ce5SGreg Kroah-Hartman * available 15096fd7ce5SGreg Kroah-Hartman * 15196fd7ce5SGreg Kroah-Hartman * Locking: 152137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 15396fd7ce5SGreg Kroah-Hartman */ 15496fd7ce5SGreg Kroah-Hartman 15536697529SPeter Hurley static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) 15696fd7ce5SGreg Kroah-Hartman { 15796fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 15896fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 15996fd7ce5SGreg Kroah-Hartman 16096fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 16196fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 16296fd7ce5SGreg Kroah-Hartman 16396fd7ce5SGreg Kroah-Hartman /* 16496fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 16596fd7ce5SGreg Kroah-Hartman * dynamically and try again. 16696fd7ce5SGreg Kroah-Hartman */ 16796fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 16896fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 16996fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 17096fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 17196fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 17296fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 17396fd7ce5SGreg Kroah-Hartman } 17496fd7ce5SGreg Kroah-Hartman 17596fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 17696fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 17796fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 17896fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 17996fd7ce5SGreg Kroah-Hartman } 18096fd7ce5SGreg Kroah-Hartman 18196fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 18236697529SPeter Hurley ld->tty = tty; 1831541f845SIvo Sieben 18496fd7ce5SGreg Kroah-Hartman return ld; 18596fd7ce5SGreg Kroah-Hartman } 18696fd7ce5SGreg Kroah-Hartman 187734de249SPeter Hurley /** 188734de249SPeter Hurley * tty_ldisc_put - release the ldisc 189734de249SPeter Hurley * 190734de249SPeter Hurley * Complement of tty_ldisc_get(). 191734de249SPeter Hurley */ 192734de249SPeter Hurley static inline void tty_ldisc_put(struct tty_ldisc *ld) 193734de249SPeter Hurley { 194734de249SPeter Hurley if (WARN_ON_ONCE(!ld)) 195734de249SPeter Hurley return; 196734de249SPeter Hurley 19736697529SPeter Hurley put_ldops(ld->ops); 198734de249SPeter Hurley kfree(ld); 199734de249SPeter Hurley } 200734de249SPeter Hurley 20196fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 20296fd7ce5SGreg Kroah-Hartman { 20396fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 20496fd7ce5SGreg Kroah-Hartman } 20596fd7ce5SGreg Kroah-Hartman 20696fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 20796fd7ce5SGreg Kroah-Hartman { 20896fd7ce5SGreg Kroah-Hartman (*pos)++; 20996fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 21096fd7ce5SGreg Kroah-Hartman } 21196fd7ce5SGreg Kroah-Hartman 21296fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 21396fd7ce5SGreg Kroah-Hartman { 21496fd7ce5SGreg Kroah-Hartman } 21596fd7ce5SGreg Kroah-Hartman 21696fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 21796fd7ce5SGreg Kroah-Hartman { 21896fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 21996fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 22096fd7ce5SGreg Kroah-Hartman 22196fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 22296fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 22396fd7ce5SGreg Kroah-Hartman return 0; 22496fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 22596fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 22696fd7ce5SGreg Kroah-Hartman return 0; 22796fd7ce5SGreg Kroah-Hartman } 22896fd7ce5SGreg Kroah-Hartman 22996fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 23096fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 23196fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 23296fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 23396fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 23496fd7ce5SGreg Kroah-Hartman }; 23596fd7ce5SGreg Kroah-Hartman 23696fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 23796fd7ce5SGreg Kroah-Hartman { 23896fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 23996fd7ce5SGreg Kroah-Hartman } 24096fd7ce5SGreg Kroah-Hartman 24196fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 24296fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 24396fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 24496fd7ce5SGreg Kroah-Hartman .read = seq_read, 24596fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 24696fd7ce5SGreg Kroah-Hartman .release = seq_release, 24796fd7ce5SGreg Kroah-Hartman }; 24896fd7ce5SGreg Kroah-Hartman 24996fd7ce5SGreg Kroah-Hartman /** 25096fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 25196fd7ce5SGreg Kroah-Hartman * @tty: tty device 25296fd7ce5SGreg Kroah-Hartman * 25396fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 25496fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 25596fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 25696fd7ce5SGreg Kroah-Hartman * 25796fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 25896fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 25996fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 26096fd7ce5SGreg Kroah-Hartman * (which we check for) 26196fd7ce5SGreg Kroah-Hartman * 26236697529SPeter Hurley * Note: only callable from a file_operations routine (which 26336697529SPeter Hurley * guarantees tty->ldisc != NULL when the lock is acquired). 26496fd7ce5SGreg Kroah-Hartman */ 26596fd7ce5SGreg Kroah-Hartman 26696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 26796fd7ce5SGreg Kroah-Hartman { 26836697529SPeter Hurley ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); 26936697529SPeter Hurley WARN_ON(!tty->ldisc); 27036697529SPeter Hurley return tty->ldisc; 27196fd7ce5SGreg Kroah-Hartman } 27296fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 27396fd7ce5SGreg Kroah-Hartman 27496fd7ce5SGreg Kroah-Hartman /** 27596fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 27696fd7ce5SGreg Kroah-Hartman * @tty: tty device 27796fd7ce5SGreg Kroah-Hartman * 27896fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 27996fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 28096fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 28196fd7ce5SGreg Kroah-Hartman */ 28296fd7ce5SGreg Kroah-Hartman 28396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 28496fd7ce5SGreg Kroah-Hartman { 28536697529SPeter Hurley struct tty_ldisc *ld = NULL; 28636697529SPeter Hurley 28736697529SPeter Hurley if (ldsem_down_read_trylock(&tty->ldisc_sem)) { 28836697529SPeter Hurley ld = tty->ldisc; 28936697529SPeter Hurley if (!ld) 29036697529SPeter Hurley ldsem_up_read(&tty->ldisc_sem); 29136697529SPeter Hurley } 29236697529SPeter Hurley return ld; 29396fd7ce5SGreg Kroah-Hartman } 29496fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 29596fd7ce5SGreg Kroah-Hartman 29696fd7ce5SGreg Kroah-Hartman /** 29796fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 29896fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 29996fd7ce5SGreg Kroah-Hartman * 30096fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 30196fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 30296fd7ce5SGreg Kroah-Hartman */ 30396fd7ce5SGreg Kroah-Hartman 30496fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 30596fd7ce5SGreg Kroah-Hartman { 30636697529SPeter Hurley ldsem_up_read(&ld->tty->ldisc_sem); 30796fd7ce5SGreg Kroah-Hartman } 30896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 30996fd7ce5SGreg Kroah-Hartman 310d2c43890SPeter Hurley 311d2c43890SPeter Hurley static inline int __lockfunc 312d2c43890SPeter Hurley tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 313d2c43890SPeter Hurley { 314d2c43890SPeter Hurley return ldsem_down_write(&tty->ldisc_sem, timeout); 315d2c43890SPeter Hurley } 316d2c43890SPeter Hurley 317d2c43890SPeter Hurley static inline int __lockfunc 318d2c43890SPeter Hurley tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) 319d2c43890SPeter Hurley { 320d2c43890SPeter Hurley return ldsem_down_write_nested(&tty->ldisc_sem, 321d2c43890SPeter Hurley LDISC_SEM_OTHER, timeout); 322d2c43890SPeter Hurley } 323d2c43890SPeter Hurley 324d2c43890SPeter Hurley static inline void tty_ldisc_unlock(struct tty_struct *tty) 325d2c43890SPeter Hurley { 326d2c43890SPeter Hurley return ldsem_up_write(&tty->ldisc_sem); 327d2c43890SPeter Hurley } 328d2c43890SPeter Hurley 329d2c43890SPeter Hurley static int __lockfunc 330d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, 331d2c43890SPeter Hurley unsigned long timeout) 332d2c43890SPeter Hurley { 333d2c43890SPeter Hurley int ret; 334d2c43890SPeter Hurley 335d2c43890SPeter Hurley if (tty < tty2) { 336d2c43890SPeter Hurley ret = tty_ldisc_lock(tty, timeout); 337d2c43890SPeter Hurley if (ret) { 338d2c43890SPeter Hurley ret = tty_ldisc_lock_nested(tty2, timeout); 339d2c43890SPeter Hurley if (!ret) 340d2c43890SPeter Hurley tty_ldisc_unlock(tty); 341d2c43890SPeter Hurley } 342d2c43890SPeter Hurley } else { 343d2c43890SPeter Hurley /* if this is possible, it has lots of implications */ 344d2c43890SPeter Hurley WARN_ON_ONCE(tty == tty2); 345d2c43890SPeter Hurley if (tty2 && tty != tty2) { 346d2c43890SPeter Hurley ret = tty_ldisc_lock(tty2, timeout); 347d2c43890SPeter Hurley if (ret) { 348d2c43890SPeter Hurley ret = tty_ldisc_lock_nested(tty, timeout); 349d2c43890SPeter Hurley if (!ret) 350d2c43890SPeter Hurley tty_ldisc_unlock(tty2); 351d2c43890SPeter Hurley } 352d2c43890SPeter Hurley } else 353d2c43890SPeter Hurley ret = tty_ldisc_lock(tty, timeout); 354d2c43890SPeter Hurley } 355d2c43890SPeter Hurley 356d2c43890SPeter Hurley if (!ret) 357d2c43890SPeter Hurley return -EBUSY; 358d2c43890SPeter Hurley 359d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty->flags); 360d2c43890SPeter Hurley if (tty2) 361d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty2->flags); 362d2c43890SPeter Hurley return 0; 363d2c43890SPeter Hurley } 364d2c43890SPeter Hurley 365d2c43890SPeter Hurley static void __lockfunc 366d2c43890SPeter Hurley tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) 367d2c43890SPeter Hurley { 368d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); 369d2c43890SPeter Hurley } 370d2c43890SPeter Hurley 371d2c43890SPeter Hurley static void __lockfunc tty_ldisc_unlock_pair(struct tty_struct *tty, 372d2c43890SPeter Hurley struct tty_struct *tty2) 373d2c43890SPeter Hurley { 374d2c43890SPeter Hurley tty_ldisc_unlock(tty); 375d2c43890SPeter Hurley if (tty2) 376d2c43890SPeter Hurley tty_ldisc_unlock(tty2); 377d2c43890SPeter Hurley } 378d2c43890SPeter Hurley 379d2c43890SPeter Hurley static void __lockfunc tty_ldisc_enable_pair(struct tty_struct *tty, 380d2c43890SPeter Hurley struct tty_struct *tty2) 381d2c43890SPeter Hurley { 382d2c43890SPeter Hurley clear_bit(TTY_LDISC_HALTED, &tty->flags); 383d2c43890SPeter Hurley if (tty2) 384d2c43890SPeter Hurley clear_bit(TTY_LDISC_HALTED, &tty2->flags); 385d2c43890SPeter Hurley 386d2c43890SPeter Hurley tty_ldisc_unlock_pair(tty, tty2); 387d2c43890SPeter Hurley } 388d2c43890SPeter Hurley 38996fd7ce5SGreg Kroah-Hartman /** 39096fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 39196fd7ce5SGreg Kroah-Hartman * @tty: tty 39296fd7ce5SGreg Kroah-Hartman * 39396fd7ce5SGreg Kroah-Hartman * Flush the line discipline queue (if any) for this tty. If there 39496fd7ce5SGreg Kroah-Hartman * is no line discipline active this is a no-op. 39596fd7ce5SGreg Kroah-Hartman */ 39696fd7ce5SGreg Kroah-Hartman 39796fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 39896fd7ce5SGreg Kroah-Hartman { 39996fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 40096fd7ce5SGreg Kroah-Hartman if (ld) { 40196fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 40296fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 40396fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 40496fd7ce5SGreg Kroah-Hartman } 40596fd7ce5SGreg Kroah-Hartman tty_buffer_flush(tty); 40696fd7ce5SGreg Kroah-Hartman } 40796fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 40896fd7ce5SGreg Kroah-Hartman 40996fd7ce5SGreg Kroah-Hartman /** 41096fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 41196fd7ce5SGreg Kroah-Hartman * @tty: tty structure 41296fd7ce5SGreg Kroah-Hartman * @num: line discipline number 41396fd7ce5SGreg Kroah-Hartman * 41496fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 41596fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 41696fd7ce5SGreg Kroah-Hartman * any harm. 41796fd7ce5SGreg Kroah-Hartman * 4186a1c0680SPeter Hurley * Locking: takes termios_rwsem 41996fd7ce5SGreg Kroah-Hartman */ 42096fd7ce5SGreg Kroah-Hartman 42196fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 42296fd7ce5SGreg Kroah-Hartman { 4236a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 424adc8d746SAlan Cox tty->termios.c_line = num; 4256a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 42696fd7ce5SGreg Kroah-Hartman } 42796fd7ce5SGreg Kroah-Hartman 42896fd7ce5SGreg Kroah-Hartman /** 42996fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 43096fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 43196fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 43296fd7ce5SGreg Kroah-Hartman * 43396fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 43496fd7ce5SGreg Kroah-Hartman * point. 43596fd7ce5SGreg Kroah-Hartman * 43696fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 43796fd7ce5SGreg Kroah-Hartman */ 43896fd7ce5SGreg Kroah-Hartman 43996fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 44096fd7ce5SGreg Kroah-Hartman { 44196fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 44296fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 44396fd7ce5SGreg Kroah-Hartman int ret; 44496fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 44596fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4467f90cfc5SJiri Slaby if (ret) 4477f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 44896fd7ce5SGreg Kroah-Hartman return ret; 44996fd7ce5SGreg Kroah-Hartman } 45096fd7ce5SGreg Kroah-Hartman return 0; 45196fd7ce5SGreg Kroah-Hartman } 45296fd7ce5SGreg Kroah-Hartman 45396fd7ce5SGreg Kroah-Hartman /** 45496fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 45596fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 45696fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 45796fd7ce5SGreg Kroah-Hartman * 45896fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 45996fd7ce5SGreg Kroah-Hartman * point. 46096fd7ce5SGreg Kroah-Hartman */ 46196fd7ce5SGreg Kroah-Hartman 46296fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 46396fd7ce5SGreg Kroah-Hartman { 46496fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 46596fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 46696fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 46796fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 46896fd7ce5SGreg Kroah-Hartman } 46996fd7ce5SGreg Kroah-Hartman 47096fd7ce5SGreg Kroah-Hartman /** 47196fd7ce5SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 47296fd7ce5SGreg Kroah-Hartman * @tty: tty to recover 47396fd7ce5SGreg Kroah-Hartman * @old: previous ldisc 47496fd7ce5SGreg Kroah-Hartman * 47596fd7ce5SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 47696fd7ce5SGreg Kroah-Hartman * change fails due to an open error 47796fd7ce5SGreg Kroah-Hartman */ 47896fd7ce5SGreg Kroah-Hartman 47996fd7ce5SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 48096fd7ce5SGreg Kroah-Hartman { 48196fd7ce5SGreg Kroah-Hartman char buf[64]; 48296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *new_ldisc; 48396fd7ce5SGreg Kroah-Hartman int r; 48496fd7ce5SGreg Kroah-Hartman 48596fd7ce5SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 48636697529SPeter Hurley old = tty_ldisc_get(tty, old->ops->num); 48796fd7ce5SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 488f4807045SPeter Hurley tty->ldisc = old; 48996fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 49096fd7ce5SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 49196fd7ce5SGreg Kroah-Hartman tty_ldisc_put(old); 49296fd7ce5SGreg Kroah-Hartman /* This driver is always present */ 49336697529SPeter Hurley new_ldisc = tty_ldisc_get(tty, N_TTY); 49496fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 49596fd7ce5SGreg Kroah-Hartman panic("n_tty: get"); 496f4807045SPeter Hurley tty->ldisc = new_ldisc; 49796fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 49896fd7ce5SGreg Kroah-Hartman r = tty_ldisc_open(tty, new_ldisc); 49996fd7ce5SGreg Kroah-Hartman if (r < 0) 50096fd7ce5SGreg Kroah-Hartman panic("Couldn't open N_TTY ldisc for " 50196fd7ce5SGreg Kroah-Hartman "%s --- error %d.", 50296fd7ce5SGreg Kroah-Hartman tty_name(tty, buf), r); 50396fd7ce5SGreg Kroah-Hartman } 50496fd7ce5SGreg Kroah-Hartman } 50596fd7ce5SGreg Kroah-Hartman 50696fd7ce5SGreg Kroah-Hartman /** 50796fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 50896fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 50996fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 51096fd7ce5SGreg Kroah-Hartman * 51196fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 51296fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 51396fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 51496fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 51596fd7ce5SGreg Kroah-Hartman */ 51696fd7ce5SGreg Kroah-Hartman 51796fd7ce5SGreg Kroah-Hartman int tty_set_ldisc(struct tty_struct *tty, int ldisc) 51896fd7ce5SGreg Kroah-Hartman { 51996fd7ce5SGreg Kroah-Hartman int retval; 5209fbfa34cSPeter Hurley struct tty_ldisc *old_ldisc, *new_ldisc; 52136697529SPeter Hurley struct tty_struct *o_tty = tty->link; 52296fd7ce5SGreg Kroah-Hartman 52336697529SPeter Hurley new_ldisc = tty_ldisc_get(tty, ldisc); 52496fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 52596fd7ce5SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 52696fd7ce5SGreg Kroah-Hartman 52736697529SPeter Hurley retval = tty_ldisc_lock_pair_timeout(tty, o_tty, 5 * HZ); 52836697529SPeter Hurley if (retval) { 52936697529SPeter Hurley tty_ldisc_put(new_ldisc); 53036697529SPeter Hurley return retval; 53136697529SPeter Hurley } 53296fd7ce5SGreg Kroah-Hartman 53396fd7ce5SGreg Kroah-Hartman /* 53496fd7ce5SGreg Kroah-Hartman * Check the no-op case 53596fd7ce5SGreg Kroah-Hartman */ 53696fd7ce5SGreg Kroah-Hartman 53796fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num == ldisc) { 53836697529SPeter Hurley tty_ldisc_enable_pair(tty, o_tty); 53996fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 54096fd7ce5SGreg Kroah-Hartman return 0; 54196fd7ce5SGreg Kroah-Hartman } 54296fd7ce5SGreg Kroah-Hartman 5439fbfa34cSPeter Hurley old_ldisc = tty->ldisc; 54489c8d91eSAlan Cox tty_lock(tty); 545100eeae2SJiri Slaby 546e97733caSPeter Hurley if (test_bit(TTY_HUPPING, &tty->flags) || 547e97733caSPeter Hurley test_bit(TTY_HUPPED, &tty->flags)) { 54896fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 54996fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 55036697529SPeter Hurley tty_ldisc_enable_pair(tty, o_tty); 55196fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 55289c8d91eSAlan Cox tty_unlock(tty); 55396fd7ce5SGreg Kroah-Hartman return -EIO; 55496fd7ce5SGreg Kroah-Hartman } 55596fd7ce5SGreg Kroah-Hartman 5569fbfa34cSPeter Hurley /* Shutdown the old discipline. */ 5579fbfa34cSPeter Hurley tty_ldisc_close(tty, old_ldisc); 55896fd7ce5SGreg Kroah-Hartman 55996fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 560f4807045SPeter Hurley tty->ldisc = new_ldisc; 56196fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 56296fd7ce5SGreg Kroah-Hartman 56396fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 56496fd7ce5SGreg Kroah-Hartman if (retval < 0) { 56596fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 56696fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 5679fbfa34cSPeter Hurley tty_ldisc_restore(tty, old_ldisc); 56896fd7ce5SGreg Kroah-Hartman } 56996fd7ce5SGreg Kroah-Hartman 5709fbfa34cSPeter Hurley if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) 57196fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 57296fd7ce5SGreg Kroah-Hartman 573b0e95858SPeter Hurley /* At this point we hold a reference to the new ldisc and a 574b0e95858SPeter Hurley reference to the old ldisc, or we hold two references to 575b0e95858SPeter Hurley the old ldisc (if it was restored as part of error cleanup 576b0e95858SPeter Hurley above). In either case, releasing a single reference from 577b0e95858SPeter Hurley the old ldisc is correct. */ 578b0e95858SPeter Hurley 5799fbfa34cSPeter Hurley tty_ldisc_put(old_ldisc); 58096fd7ce5SGreg Kroah-Hartman 58196fd7ce5SGreg Kroah-Hartman /* 58296fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 58396fd7ce5SGreg Kroah-Hartman */ 58436697529SPeter Hurley tty_ldisc_enable_pair(tty, o_tty); 58596fd7ce5SGreg Kroah-Hartman 58696fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 58796fd7ce5SGreg Kroah-Hartman already running */ 588ecbbfd44SJiri Slaby schedule_work(&tty->port->buf.work); 5894f98d467SPeter Hurley if (o_tty) 590ecbbfd44SJiri Slaby schedule_work(&o_tty->port->buf.work); 5914f98d467SPeter Hurley 59289c8d91eSAlan Cox tty_unlock(tty); 59396fd7ce5SGreg Kroah-Hartman return retval; 59496fd7ce5SGreg Kroah-Hartman } 59596fd7ce5SGreg Kroah-Hartman 59696fd7ce5SGreg Kroah-Hartman /** 59796fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 59896fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 59996fd7ce5SGreg Kroah-Hartman * 60096fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 60196fd7ce5SGreg Kroah-Hartman */ 60296fd7ce5SGreg Kroah-Hartman 60396fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 60496fd7ce5SGreg Kroah-Hartman { 6056a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 606adc8d746SAlan Cox tty->termios = tty->driver->init_termios; 607adc8d746SAlan Cox tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); 608adc8d746SAlan Cox tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); 6096a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 61096fd7ce5SGreg Kroah-Hartman } 61196fd7ce5SGreg Kroah-Hartman 61296fd7ce5SGreg Kroah-Hartman 61396fd7ce5SGreg Kroah-Hartman /** 61496fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 61596fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 61696fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 61796fd7ce5SGreg Kroah-Hartman * 61896fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 61996fd7ce5SGreg Kroah-Hartman * state closed 62096fd7ce5SGreg Kroah-Hartman */ 62196fd7ce5SGreg Kroah-Hartman 6221c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 62396fd7ce5SGreg Kroah-Hartman { 62436697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, ldisc); 6251c95ba1eSPhilippe Rétornaz 6261c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 6271c95ba1eSPhilippe Rétornaz return -1; 62896fd7ce5SGreg Kroah-Hartman 62996fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 63096fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 63196fd7ce5SGreg Kroah-Hartman /* 63296fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 63396fd7ce5SGreg Kroah-Hartman */ 634f4807045SPeter Hurley tty->ldisc = ld; 63596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 6361c95ba1eSPhilippe Rétornaz 6371c95ba1eSPhilippe Rétornaz return 0; 63896fd7ce5SGreg Kroah-Hartman } 63996fd7ce5SGreg Kroah-Hartman 64096fd7ce5SGreg Kroah-Hartman /** 64196fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 64296fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 64396fd7ce5SGreg Kroah-Hartman * 64496fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 64596fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 64696fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 64796fd7ce5SGreg Kroah-Hartman * 64896fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 64996fd7ce5SGreg Kroah-Hartman * careful to allow for this. 65096fd7ce5SGreg Kroah-Hartman * 65196fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 65296fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 65396fd7ce5SGreg Kroah-Hartman */ 65496fd7ce5SGreg Kroah-Hartman 65596fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 65696fd7ce5SGreg Kroah-Hartman { 65796fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 65896fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 65996fd7ce5SGreg Kroah-Hartman int err = 0; 66096fd7ce5SGreg Kroah-Hartman 661fc575ee6SPeter Hurley tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); 662fc575ee6SPeter Hurley 66396fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 66496fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 66596fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 66696fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 66796fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 66896fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 66996fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 67096fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 67196fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 67296fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 67396fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 67496fd7ce5SGreg Kroah-Hartman } 67536697529SPeter Hurley 67696fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 67796fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 67836697529SPeter Hurley 67936697529SPeter Hurley tty_unlock(tty); 68036697529SPeter Hurley 68196fd7ce5SGreg Kroah-Hartman /* 68296fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 68396fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 68496fd7ce5SGreg Kroah-Hartman * 68596fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 68696fd7ce5SGreg Kroah-Hartman */ 68736697529SPeter Hurley tty_ldisc_lock_pair(tty, tty->link); 68836697529SPeter Hurley tty_lock(tty); 68996fd7ce5SGreg Kroah-Hartman 69036697529SPeter Hurley if (tty->ldisc) { 691c8785241SPeter Hurley 692c8785241SPeter Hurley /* At this point we have a halted ldisc; we want to close it and 693c8785241SPeter Hurley reopen a new ldisc. We could defer the reopen to the next 694c8785241SPeter Hurley open but it means auditing a lot of other paths so this is 695c8785241SPeter Hurley a FIXME */ 69696fd7ce5SGreg Kroah-Hartman if (reset == 0) { 6971c95ba1eSPhilippe Rétornaz 698adc8d746SAlan Cox if (!tty_ldisc_reinit(tty, tty->termios.c_line)) 69996fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 7001c95ba1eSPhilippe Rétornaz else 7011c95ba1eSPhilippe Rétornaz err = 1; 70296fd7ce5SGreg Kroah-Hartman } 70396fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 70496fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 70596fd7ce5SGreg Kroah-Hartman if (reset || err) { 7061c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 70796fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 70896fd7ce5SGreg Kroah-Hartman } 70996fd7ce5SGreg Kroah-Hartman } 71036697529SPeter Hurley tty_ldisc_enable_pair(tty, tty->link); 71196fd7ce5SGreg Kroah-Hartman if (reset) 71296fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 713fc575ee6SPeter Hurley 714fc575ee6SPeter Hurley tty_ldisc_debug(tty, "re-opened ldisc: %p\n", tty->ldisc); 71596fd7ce5SGreg Kroah-Hartman } 71696fd7ce5SGreg Kroah-Hartman 71796fd7ce5SGreg Kroah-Hartman /** 71896fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 71996fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 72096fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 72196fd7ce5SGreg Kroah-Hartman * 72296fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 72396fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 72496fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 72596fd7ce5SGreg Kroah-Hartman */ 72696fd7ce5SGreg Kroah-Hartman 72796fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 72896fd7ce5SGreg Kroah-Hartman { 72996fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 73096fd7ce5SGreg Kroah-Hartman int retval; 73196fd7ce5SGreg Kroah-Hartman 73296fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 73396fd7ce5SGreg Kroah-Hartman if (retval) 73496fd7ce5SGreg Kroah-Hartman return retval; 73596fd7ce5SGreg Kroah-Hartman 73696fd7ce5SGreg Kroah-Hartman if (o_tty) { 73796fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 73896fd7ce5SGreg Kroah-Hartman if (retval) { 73996fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 74096fd7ce5SGreg Kroah-Hartman return retval; 74196fd7ce5SGreg Kroah-Hartman } 74296fd7ce5SGreg Kroah-Hartman } 74396fd7ce5SGreg Kroah-Hartman return 0; 74496fd7ce5SGreg Kroah-Hartman } 74589c8d91eSAlan Cox 74689c8d91eSAlan Cox static void tty_ldisc_kill(struct tty_struct *tty) 74789c8d91eSAlan Cox { 74889c8d91eSAlan Cox /* 74989c8d91eSAlan Cox * Now kill off the ldisc 75089c8d91eSAlan Cox */ 75189c8d91eSAlan Cox tty_ldisc_close(tty, tty->ldisc); 75289c8d91eSAlan Cox tty_ldisc_put(tty->ldisc); 75389c8d91eSAlan Cox /* Force an oops if we mess this up */ 75489c8d91eSAlan Cox tty->ldisc = NULL; 75589c8d91eSAlan Cox 75689c8d91eSAlan Cox /* Ensure the next open requests the N_TTY ldisc */ 75789c8d91eSAlan Cox tty_set_termios_ldisc(tty, N_TTY); 75889c8d91eSAlan Cox } 75989c8d91eSAlan Cox 76096fd7ce5SGreg Kroah-Hartman /** 76196fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 76296fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 76396fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 76496fd7ce5SGreg Kroah-Hartman * 76596fd7ce5SGreg Kroah-Hartman * Called during the final close of a tty/pty pair in order to shut down 76696fd7ce5SGreg Kroah-Hartman * the line discpline layer. On exit the ldisc assigned is N_TTY and the 76796fd7ce5SGreg Kroah-Hartman * ldisc has not been opened. 76896fd7ce5SGreg Kroah-Hartman */ 76996fd7ce5SGreg Kroah-Hartman 77096fd7ce5SGreg Kroah-Hartman void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) 77196fd7ce5SGreg Kroah-Hartman { 77296fd7ce5SGreg Kroah-Hartman /* 773a2965b7bSPeter Hurley * Shutdown this line discipline. As this is the final close, 774a2965b7bSPeter Hurley * it does not race with the set_ldisc code path. 77596fd7ce5SGreg Kroah-Hartman */ 77696fd7ce5SGreg Kroah-Hartman 777fc575ee6SPeter Hurley tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); 778fc575ee6SPeter Hurley 77936697529SPeter Hurley tty_ldisc_lock_pair(tty, o_tty); 780852e4a81SSebastian Andrzej Siewior tty_lock_pair(tty, o_tty); 78136697529SPeter Hurley 78289c8d91eSAlan Cox tty_ldisc_kill(tty); 78389c8d91eSAlan Cox if (o_tty) 78489c8d91eSAlan Cox tty_ldisc_kill(o_tty); 78589c8d91eSAlan Cox 78689c8d91eSAlan Cox tty_unlock_pair(tty, o_tty); 78736697529SPeter Hurley tty_ldisc_unlock_pair(tty, o_tty); 78836697529SPeter Hurley 78996fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 79096fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 791fc575ee6SPeter Hurley 792fc575ee6SPeter Hurley tty_ldisc_debug(tty, "ldisc closed\n"); 79396fd7ce5SGreg Kroah-Hartman } 79496fd7ce5SGreg Kroah-Hartman 79596fd7ce5SGreg Kroah-Hartman /** 79696fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 79796fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 79896fd7ce5SGreg Kroah-Hartman * 79996fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 80096fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 80196fd7ce5SGreg Kroah-Hartman */ 80296fd7ce5SGreg Kroah-Hartman 80396fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 80496fd7ce5SGreg Kroah-Hartman { 80536697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); 80696fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 80796fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 808f4807045SPeter Hurley tty->ldisc = ld; 80996fd7ce5SGreg Kroah-Hartman } 81096fd7ce5SGreg Kroah-Hartman 8116716671dSJiri Slaby /** 8126716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 8136716671dSJiri Slaby * @tty: tty that was allocated recently 8146716671dSJiri Slaby * 8156716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 8166716671dSJiri Slaby * this call is made. 8176716671dSJiri Slaby */ 8186716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 8196716671dSJiri Slaby { 820ebc9baedSPeter Hurley tty_ldisc_put(tty->ldisc); 821f4807045SPeter Hurley tty->ldisc = NULL; 8226716671dSJiri Slaby } 8236716671dSJiri Slaby 82496fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 82596fd7ce5SGreg Kroah-Hartman { 82696fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 82796fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 82896fd7ce5SGreg Kroah-Hartman } 829