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 * 41896fd7ce5SGreg Kroah-Hartman * Locking: takes termios_mutex 41996fd7ce5SGreg Kroah-Hartman */ 42096fd7ce5SGreg Kroah-Hartman 42196fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 42296fd7ce5SGreg Kroah-Hartman { 42396fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 424adc8d746SAlan Cox tty->termios.c_line = num; 42596fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 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 54336697529SPeter Hurley /* FIXME: why 'shutoff' input if the ldisc is locked? */ 54496fd7ce5SGreg Kroah-Hartman tty->receive_room = 0; 54596fd7ce5SGreg Kroah-Hartman 5469fbfa34cSPeter Hurley old_ldisc = tty->ldisc; 54789c8d91eSAlan Cox tty_lock(tty); 548100eeae2SJiri Slaby 54936697529SPeter Hurley /* FIXME: for testing only */ 55036697529SPeter Hurley WARN_ON(test_bit(TTY_HUPPED, &tty->flags)); 551100eeae2SJiri Slaby 55240c9f61eSShachar Shemesh if (test_bit(TTY_HUPPING, &tty->flags)) { 55396fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 55496fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 55536697529SPeter Hurley tty_ldisc_enable_pair(tty, o_tty); 55696fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 55789c8d91eSAlan Cox tty_unlock(tty); 55896fd7ce5SGreg Kroah-Hartman return -EIO; 55996fd7ce5SGreg Kroah-Hartman } 56096fd7ce5SGreg Kroah-Hartman 5619fbfa34cSPeter Hurley /* Shutdown the old discipline. */ 5629fbfa34cSPeter Hurley tty_ldisc_close(tty, old_ldisc); 56396fd7ce5SGreg Kroah-Hartman 56496fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 565f4807045SPeter Hurley tty->ldisc = new_ldisc; 56696fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 56796fd7ce5SGreg Kroah-Hartman 56896fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 56996fd7ce5SGreg Kroah-Hartman if (retval < 0) { 57096fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 57196fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 5729fbfa34cSPeter Hurley tty_ldisc_restore(tty, old_ldisc); 57396fd7ce5SGreg Kroah-Hartman } 57496fd7ce5SGreg Kroah-Hartman 57596fd7ce5SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 57696fd7ce5SGreg Kroah-Hartman a reference to the old ldisc. If we ended up flipping back 57796fd7ce5SGreg Kroah-Hartman to the existing ldisc we have two references to it */ 57896fd7ce5SGreg Kroah-Hartman 5799fbfa34cSPeter Hurley if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) 58096fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 58196fd7ce5SGreg Kroah-Hartman 5829fbfa34cSPeter Hurley tty_ldisc_put(old_ldisc); 58396fd7ce5SGreg Kroah-Hartman 58496fd7ce5SGreg Kroah-Hartman /* 58596fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 58696fd7ce5SGreg Kroah-Hartman */ 58736697529SPeter Hurley tty_ldisc_enable_pair(tty, o_tty); 58896fd7ce5SGreg Kroah-Hartman 58996fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 59096fd7ce5SGreg Kroah-Hartman already running */ 591ecbbfd44SJiri Slaby schedule_work(&tty->port->buf.work); 5924f98d467SPeter Hurley if (o_tty) 593ecbbfd44SJiri Slaby schedule_work(&o_tty->port->buf.work); 5944f98d467SPeter Hurley 59589c8d91eSAlan Cox tty_unlock(tty); 59696fd7ce5SGreg Kroah-Hartman return retval; 59796fd7ce5SGreg Kroah-Hartman } 59896fd7ce5SGreg Kroah-Hartman 59996fd7ce5SGreg Kroah-Hartman /** 60096fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 60196fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 60296fd7ce5SGreg Kroah-Hartman * 60396fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 60496fd7ce5SGreg Kroah-Hartman */ 60596fd7ce5SGreg Kroah-Hartman 60696fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 60796fd7ce5SGreg Kroah-Hartman { 60896fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 609adc8d746SAlan Cox tty->termios = tty->driver->init_termios; 610adc8d746SAlan Cox tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); 611adc8d746SAlan Cox tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); 61296fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 61396fd7ce5SGreg Kroah-Hartman } 61496fd7ce5SGreg Kroah-Hartman 61596fd7ce5SGreg Kroah-Hartman 61696fd7ce5SGreg Kroah-Hartman /** 61796fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 61896fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 61996fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 62096fd7ce5SGreg Kroah-Hartman * 62196fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 62296fd7ce5SGreg Kroah-Hartman * state closed 62396fd7ce5SGreg Kroah-Hartman */ 62496fd7ce5SGreg Kroah-Hartman 6251c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 62696fd7ce5SGreg Kroah-Hartman { 62736697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, ldisc); 6281c95ba1eSPhilippe Rétornaz 6291c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 6301c95ba1eSPhilippe Rétornaz return -1; 63196fd7ce5SGreg Kroah-Hartman 63296fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 63396fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 63496fd7ce5SGreg Kroah-Hartman /* 63596fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 63696fd7ce5SGreg Kroah-Hartman */ 637f4807045SPeter Hurley tty->ldisc = ld; 63896fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 6391c95ba1eSPhilippe Rétornaz 6401c95ba1eSPhilippe Rétornaz return 0; 64196fd7ce5SGreg Kroah-Hartman } 64296fd7ce5SGreg Kroah-Hartman 64396fd7ce5SGreg Kroah-Hartman /** 64496fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 64596fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 64696fd7ce5SGreg Kroah-Hartman * 64796fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 64896fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 64996fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 65096fd7ce5SGreg Kroah-Hartman * 65196fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 65296fd7ce5SGreg Kroah-Hartman * careful to allow for this. 65396fd7ce5SGreg Kroah-Hartman * 65496fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 65596fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 65696fd7ce5SGreg Kroah-Hartman */ 65796fd7ce5SGreg Kroah-Hartman 65896fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 65996fd7ce5SGreg Kroah-Hartman { 66096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 66196fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 66296fd7ce5SGreg Kroah-Hartman int err = 0; 66396fd7ce5SGreg Kroah-Hartman 664fc575ee6SPeter Hurley tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); 665fc575ee6SPeter Hurley 66696fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 66796fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 66896fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 66996fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 67096fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 67196fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 67296fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 67396fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 67496fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 67596fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 67696fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 67796fd7ce5SGreg Kroah-Hartman } 67836697529SPeter Hurley 67996fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 68096fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 68136697529SPeter Hurley 68236697529SPeter Hurley tty_unlock(tty); 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 */ 69036697529SPeter Hurley tty_ldisc_lock_pair(tty, tty->link); 69136697529SPeter Hurley tty_lock(tty); 69296fd7ce5SGreg Kroah-Hartman 69336697529SPeter Hurley if (tty->ldisc) { 694c8785241SPeter Hurley 695c8785241SPeter Hurley /* At this point we have a halted ldisc; we want to close it and 696c8785241SPeter Hurley reopen a new ldisc. We could defer the reopen to the next 697c8785241SPeter Hurley open but it means auditing a lot of other paths so this is 698c8785241SPeter Hurley a FIXME */ 69996fd7ce5SGreg Kroah-Hartman if (reset == 0) { 7001c95ba1eSPhilippe Rétornaz 701adc8d746SAlan Cox if (!tty_ldisc_reinit(tty, tty->termios.c_line)) 70296fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 7031c95ba1eSPhilippe Rétornaz else 7041c95ba1eSPhilippe Rétornaz err = 1; 70596fd7ce5SGreg Kroah-Hartman } 70696fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 70796fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 70896fd7ce5SGreg Kroah-Hartman if (reset || err) { 7091c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 71096fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 71196fd7ce5SGreg Kroah-Hartman } 71296fd7ce5SGreg Kroah-Hartman } 71336697529SPeter Hurley tty_ldisc_enable_pair(tty, tty->link); 71496fd7ce5SGreg Kroah-Hartman if (reset) 71596fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 716fc575ee6SPeter Hurley 717fc575ee6SPeter Hurley tty_ldisc_debug(tty, "re-opened ldisc: %p\n", tty->ldisc); 71896fd7ce5SGreg Kroah-Hartman } 71996fd7ce5SGreg Kroah-Hartman 72096fd7ce5SGreg Kroah-Hartman /** 72196fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 72296fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 72396fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 72496fd7ce5SGreg Kroah-Hartman * 72596fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 72696fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 72796fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 72896fd7ce5SGreg Kroah-Hartman */ 72996fd7ce5SGreg Kroah-Hartman 73096fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 73196fd7ce5SGreg Kroah-Hartman { 73296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 73396fd7ce5SGreg Kroah-Hartman int retval; 73496fd7ce5SGreg Kroah-Hartman 73596fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 73696fd7ce5SGreg Kroah-Hartman if (retval) 73796fd7ce5SGreg Kroah-Hartman return retval; 73896fd7ce5SGreg Kroah-Hartman 73996fd7ce5SGreg Kroah-Hartman if (o_tty) { 74096fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 74196fd7ce5SGreg Kroah-Hartman if (retval) { 74296fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 74396fd7ce5SGreg Kroah-Hartman return retval; 74496fd7ce5SGreg Kroah-Hartman } 74596fd7ce5SGreg Kroah-Hartman } 74696fd7ce5SGreg Kroah-Hartman return 0; 74796fd7ce5SGreg Kroah-Hartman } 74889c8d91eSAlan Cox 74989c8d91eSAlan Cox static void tty_ldisc_kill(struct tty_struct *tty) 75089c8d91eSAlan Cox { 75189c8d91eSAlan Cox /* 75289c8d91eSAlan Cox * Now kill off the ldisc 75389c8d91eSAlan Cox */ 75489c8d91eSAlan Cox tty_ldisc_close(tty, tty->ldisc); 75589c8d91eSAlan Cox tty_ldisc_put(tty->ldisc); 75689c8d91eSAlan Cox /* Force an oops if we mess this up */ 75789c8d91eSAlan Cox tty->ldisc = NULL; 75889c8d91eSAlan Cox 75989c8d91eSAlan Cox /* Ensure the next open requests the N_TTY ldisc */ 76089c8d91eSAlan Cox tty_set_termios_ldisc(tty, N_TTY); 76189c8d91eSAlan Cox } 76289c8d91eSAlan Cox 76396fd7ce5SGreg Kroah-Hartman /** 76496fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 76596fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 76696fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 76796fd7ce5SGreg Kroah-Hartman * 76896fd7ce5SGreg Kroah-Hartman * Called during the final close of a tty/pty pair in order to shut down 76996fd7ce5SGreg Kroah-Hartman * the line discpline layer. On exit the ldisc assigned is N_TTY and the 77096fd7ce5SGreg Kroah-Hartman * ldisc has not been opened. 77196fd7ce5SGreg Kroah-Hartman */ 77296fd7ce5SGreg Kroah-Hartman 77396fd7ce5SGreg Kroah-Hartman void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) 77496fd7ce5SGreg Kroah-Hartman { 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 780fc575ee6SPeter Hurley tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc); 781fc575ee6SPeter Hurley 78236697529SPeter Hurley tty_ldisc_lock_pair(tty, o_tty); 783852e4a81SSebastian Andrzej Siewior tty_lock_pair(tty, o_tty); 78436697529SPeter Hurley 78589c8d91eSAlan Cox tty_ldisc_kill(tty); 78689c8d91eSAlan Cox if (o_tty) 78789c8d91eSAlan Cox tty_ldisc_kill(o_tty); 78889c8d91eSAlan Cox 78989c8d91eSAlan Cox tty_unlock_pair(tty, o_tty); 79036697529SPeter Hurley tty_ldisc_unlock_pair(tty, o_tty); 79136697529SPeter Hurley 79296fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 79396fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 794fc575ee6SPeter Hurley 795fc575ee6SPeter Hurley tty_ldisc_debug(tty, "ldisc closed\n"); 79696fd7ce5SGreg Kroah-Hartman } 79796fd7ce5SGreg Kroah-Hartman 79896fd7ce5SGreg Kroah-Hartman /** 79996fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 80096fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 80196fd7ce5SGreg Kroah-Hartman * 80296fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 80396fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 80496fd7ce5SGreg Kroah-Hartman */ 80596fd7ce5SGreg Kroah-Hartman 80696fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 80796fd7ce5SGreg Kroah-Hartman { 80836697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); 80996fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 81096fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 811f4807045SPeter Hurley tty->ldisc = ld; 81296fd7ce5SGreg Kroah-Hartman } 81396fd7ce5SGreg Kroah-Hartman 8146716671dSJiri Slaby /** 8156716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 8166716671dSJiri Slaby * @tty: tty that was allocated recently 8176716671dSJiri Slaby * 8186716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 8196716671dSJiri Slaby * this call is made. 8206716671dSJiri Slaby */ 8216716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 8226716671dSJiri Slaby { 823ebc9baedSPeter Hurley tty_ldisc_put(tty->ldisc); 824f4807045SPeter Hurley tty->ldisc = NULL; 8256716671dSJiri Slaby } 8266716671dSJiri Slaby 82796fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 82896fd7ce5SGreg Kroah-Hartman { 82996fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 83096fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 83196fd7ce5SGreg Kroah-Hartman } 832