196fd7ce5SGreg Kroah-Hartman #include <linux/types.h> 296fd7ce5SGreg Kroah-Hartman #include <linux/major.h> 396fd7ce5SGreg Kroah-Hartman #include <linux/errno.h> 496fd7ce5SGreg Kroah-Hartman #include <linux/signal.h> 596fd7ce5SGreg Kroah-Hartman #include <linux/fcntl.h> 696fd7ce5SGreg Kroah-Hartman #include <linux/sched.h> 796fd7ce5SGreg Kroah-Hartman #include <linux/interrupt.h> 896fd7ce5SGreg Kroah-Hartman #include <linux/tty.h> 996fd7ce5SGreg Kroah-Hartman #include <linux/tty_driver.h> 1096fd7ce5SGreg Kroah-Hartman #include <linux/tty_flip.h> 1196fd7ce5SGreg Kroah-Hartman #include <linux/devpts_fs.h> 1296fd7ce5SGreg Kroah-Hartman #include <linux/file.h> 1396fd7ce5SGreg Kroah-Hartman #include <linux/console.h> 1496fd7ce5SGreg Kroah-Hartman #include <linux/timer.h> 1596fd7ce5SGreg Kroah-Hartman #include <linux/ctype.h> 1696fd7ce5SGreg Kroah-Hartman #include <linux/kd.h> 1796fd7ce5SGreg Kroah-Hartman #include <linux/mm.h> 1896fd7ce5SGreg Kroah-Hartman #include <linux/string.h> 1996fd7ce5SGreg Kroah-Hartman #include <linux/slab.h> 2096fd7ce5SGreg Kroah-Hartman #include <linux/poll.h> 2196fd7ce5SGreg Kroah-Hartman #include <linux/proc_fs.h> 2296fd7ce5SGreg Kroah-Hartman #include <linux/init.h> 2396fd7ce5SGreg Kroah-Hartman #include <linux/module.h> 2496fd7ce5SGreg Kroah-Hartman #include <linux/device.h> 2596fd7ce5SGreg Kroah-Hartman #include <linux/wait.h> 2696fd7ce5SGreg Kroah-Hartman #include <linux/bitops.h> 2796fd7ce5SGreg Kroah-Hartman #include <linux/delay.h> 2896fd7ce5SGreg Kroah-Hartman #include <linux/seq_file.h> 2996fd7ce5SGreg Kroah-Hartman 3096fd7ce5SGreg Kroah-Hartman #include <linux/uaccess.h> 3196fd7ce5SGreg Kroah-Hartman #include <asm/system.h> 3296fd7ce5SGreg Kroah-Hartman 3396fd7ce5SGreg Kroah-Hartman #include <linux/kbd_kern.h> 3496fd7ce5SGreg Kroah-Hartman #include <linux/vt_kern.h> 3596fd7ce5SGreg Kroah-Hartman #include <linux/selection.h> 3696fd7ce5SGreg Kroah-Hartman 3796fd7ce5SGreg Kroah-Hartman #include <linux/kmod.h> 3896fd7ce5SGreg Kroah-Hartman #include <linux/nsproxy.h> 3996fd7ce5SGreg Kroah-Hartman 4096fd7ce5SGreg Kroah-Hartman /* 4196fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 4296fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4396fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4496fd7ce5SGreg Kroah-Hartman */ 4596fd7ce5SGreg Kroah-Hartman 4696fd7ce5SGreg Kroah-Hartman static DEFINE_SPINLOCK(tty_ldisc_lock); 4796fd7ce5SGreg Kroah-Hartman static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); 48100eeae2SJiri Slaby static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle); 4996fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 5096fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 5196fd7ce5SGreg Kroah-Hartman 5296fd7ce5SGreg Kroah-Hartman static inline struct tty_ldisc *get_ldisc(struct tty_ldisc *ld) 5396fd7ce5SGreg Kroah-Hartman { 5496fd7ce5SGreg Kroah-Hartman if (ld) 5596fd7ce5SGreg Kroah-Hartman atomic_inc(&ld->users); 5696fd7ce5SGreg Kroah-Hartman return ld; 5796fd7ce5SGreg Kroah-Hartman } 5896fd7ce5SGreg Kroah-Hartman 5996fd7ce5SGreg Kroah-Hartman static void put_ldisc(struct tty_ldisc *ld) 6096fd7ce5SGreg Kroah-Hartman { 6196fd7ce5SGreg Kroah-Hartman unsigned long flags; 6296fd7ce5SGreg Kroah-Hartman 6396fd7ce5SGreg Kroah-Hartman if (WARN_ON_ONCE(!ld)) 6496fd7ce5SGreg Kroah-Hartman return; 6596fd7ce5SGreg Kroah-Hartman 6696fd7ce5SGreg Kroah-Hartman /* 6796fd7ce5SGreg Kroah-Hartman * If this is the last user, free the ldisc, and 6896fd7ce5SGreg Kroah-Hartman * release the ldisc ops. 6996fd7ce5SGreg Kroah-Hartman * 7096fd7ce5SGreg Kroah-Hartman * We really want an "atomic_dec_and_lock_irqsave()", 7196fd7ce5SGreg Kroah-Hartman * but we don't have it, so this does it by hand. 7296fd7ce5SGreg Kroah-Hartman */ 7396fd7ce5SGreg Kroah-Hartman local_irq_save(flags); 7496fd7ce5SGreg Kroah-Hartman if (atomic_dec_and_lock(&ld->users, &tty_ldisc_lock)) { 7596fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldo = ld->ops; 7696fd7ce5SGreg Kroah-Hartman 7796fd7ce5SGreg Kroah-Hartman ldo->refcount--; 7896fd7ce5SGreg Kroah-Hartman module_put(ldo->owner); 7996fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 8096fd7ce5SGreg Kroah-Hartman 8196fd7ce5SGreg Kroah-Hartman kfree(ld); 8296fd7ce5SGreg Kroah-Hartman return; 8396fd7ce5SGreg Kroah-Hartman } 8496fd7ce5SGreg Kroah-Hartman local_irq_restore(flags); 85100eeae2SJiri Slaby wake_up(&tty_ldisc_idle); 8696fd7ce5SGreg Kroah-Hartman } 8796fd7ce5SGreg Kroah-Hartman 8896fd7ce5SGreg Kroah-Hartman /** 8996fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 9096fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 9196fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 9296fd7ce5SGreg Kroah-Hartman * 9396fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 9496fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 9596fd7ce5SGreg Kroah-Hartman * from this point onwards. 9696fd7ce5SGreg Kroah-Hartman * 9796fd7ce5SGreg Kroah-Hartman * Locking: 9896fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 9996fd7ce5SGreg Kroah-Hartman */ 10096fd7ce5SGreg Kroah-Hartman 10196fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 10296fd7ce5SGreg Kroah-Hartman { 10396fd7ce5SGreg Kroah-Hartman unsigned long flags; 10496fd7ce5SGreg Kroah-Hartman int ret = 0; 10596fd7ce5SGreg Kroah-Hartman 10696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 10796fd7ce5SGreg Kroah-Hartman return -EINVAL; 10896fd7ce5SGreg Kroah-Hartman 10996fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 11096fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 11196fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 11296fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 11396fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 11496fd7ce5SGreg Kroah-Hartman 11596fd7ce5SGreg Kroah-Hartman return ret; 11696fd7ce5SGreg Kroah-Hartman } 11796fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 11896fd7ce5SGreg Kroah-Hartman 11996fd7ce5SGreg Kroah-Hartman /** 12096fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 12196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 12296fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 12396fd7ce5SGreg Kroah-Hartman * 12496fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 12596fd7ce5SGreg Kroah-Hartman * currently in use. 12696fd7ce5SGreg Kroah-Hartman * 12796fd7ce5SGreg Kroah-Hartman * Locking: 12896fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 12996fd7ce5SGreg Kroah-Hartman */ 13096fd7ce5SGreg Kroah-Hartman 13196fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 13296fd7ce5SGreg Kroah-Hartman { 13396fd7ce5SGreg Kroah-Hartman unsigned long flags; 13496fd7ce5SGreg Kroah-Hartman int ret = 0; 13596fd7ce5SGreg Kroah-Hartman 13696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 13796fd7ce5SGreg Kroah-Hartman return -EINVAL; 13896fd7ce5SGreg Kroah-Hartman 13996fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 14096fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 14196fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 14296fd7ce5SGreg Kroah-Hartman else 14396fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 14496fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 14596fd7ce5SGreg Kroah-Hartman 14696fd7ce5SGreg Kroah-Hartman return ret; 14796fd7ce5SGreg Kroah-Hartman } 14896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 14996fd7ce5SGreg Kroah-Hartman 15096fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 15196fd7ce5SGreg Kroah-Hartman { 15296fd7ce5SGreg Kroah-Hartman unsigned long flags; 15396fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 15496fd7ce5SGreg Kroah-Hartman 15596fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 15696fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 15796fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 15896fd7ce5SGreg Kroah-Hartman if (ldops) { 15996fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 16096fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 16196fd7ce5SGreg Kroah-Hartman ldops->refcount++; 16296fd7ce5SGreg Kroah-Hartman ret = ldops; 16396fd7ce5SGreg Kroah-Hartman } 16496fd7ce5SGreg Kroah-Hartman } 16596fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 16696fd7ce5SGreg Kroah-Hartman return ret; 16796fd7ce5SGreg Kroah-Hartman } 16896fd7ce5SGreg Kroah-Hartman 16996fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 17096fd7ce5SGreg Kroah-Hartman { 17196fd7ce5SGreg Kroah-Hartman unsigned long flags; 17296fd7ce5SGreg Kroah-Hartman 17396fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 17496fd7ce5SGreg Kroah-Hartman ldops->refcount--; 17596fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 17696fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 17796fd7ce5SGreg Kroah-Hartman } 17896fd7ce5SGreg Kroah-Hartman 17996fd7ce5SGreg Kroah-Hartman /** 18096fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 18196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 18296fd7ce5SGreg Kroah-Hartman * 18396fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 18496fd7ce5SGreg Kroah-Hartman * module locking counts. Returns NULL if the discipline is not available. 18596fd7ce5SGreg Kroah-Hartman * Returns a pointer to the discipline and bumps the ref count if it is 18696fd7ce5SGreg Kroah-Hartman * available 18796fd7ce5SGreg Kroah-Hartman * 18896fd7ce5SGreg Kroah-Hartman * Locking: 18996fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 19096fd7ce5SGreg Kroah-Hartman */ 19196fd7ce5SGreg Kroah-Hartman 19296fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_get(int disc) 19396fd7ce5SGreg Kroah-Hartman { 19496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 19596fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 19696fd7ce5SGreg Kroah-Hartman 19796fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 19896fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 19996fd7ce5SGreg Kroah-Hartman 20096fd7ce5SGreg Kroah-Hartman /* 20196fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 20296fd7ce5SGreg Kroah-Hartman * dynamically and try again. 20396fd7ce5SGreg Kroah-Hartman */ 20496fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 20596fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 20696fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 20796fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 20896fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 20996fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 21096fd7ce5SGreg Kroah-Hartman } 21196fd7ce5SGreg Kroah-Hartman 21296fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 21396fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 21496fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 21596fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 21696fd7ce5SGreg Kroah-Hartman } 21796fd7ce5SGreg Kroah-Hartman 21896fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 21996fd7ce5SGreg Kroah-Hartman atomic_set(&ld->users, 1); 22096fd7ce5SGreg Kroah-Hartman return ld; 22196fd7ce5SGreg Kroah-Hartman } 22296fd7ce5SGreg Kroah-Hartman 22396fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 22496fd7ce5SGreg Kroah-Hartman { 22596fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 22696fd7ce5SGreg Kroah-Hartman } 22796fd7ce5SGreg Kroah-Hartman 22896fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 22996fd7ce5SGreg Kroah-Hartman { 23096fd7ce5SGreg Kroah-Hartman (*pos)++; 23196fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 23296fd7ce5SGreg Kroah-Hartman } 23396fd7ce5SGreg Kroah-Hartman 23496fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 23596fd7ce5SGreg Kroah-Hartman { 23696fd7ce5SGreg Kroah-Hartman } 23796fd7ce5SGreg Kroah-Hartman 23896fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 23996fd7ce5SGreg Kroah-Hartman { 24096fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 24196fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 24296fd7ce5SGreg Kroah-Hartman 24396fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 24496fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 24596fd7ce5SGreg Kroah-Hartman return 0; 24696fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 24796fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 24896fd7ce5SGreg Kroah-Hartman return 0; 24996fd7ce5SGreg Kroah-Hartman } 25096fd7ce5SGreg Kroah-Hartman 25196fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 25296fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 25396fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 25496fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 25596fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 25696fd7ce5SGreg Kroah-Hartman }; 25796fd7ce5SGreg Kroah-Hartman 25896fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 25996fd7ce5SGreg Kroah-Hartman { 26096fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 26196fd7ce5SGreg Kroah-Hartman } 26296fd7ce5SGreg Kroah-Hartman 26396fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 26496fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 26596fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 26696fd7ce5SGreg Kroah-Hartman .read = seq_read, 26796fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 26896fd7ce5SGreg Kroah-Hartman .release = seq_release, 26996fd7ce5SGreg Kroah-Hartman }; 27096fd7ce5SGreg Kroah-Hartman 27196fd7ce5SGreg Kroah-Hartman /** 27296fd7ce5SGreg Kroah-Hartman * tty_ldisc_assign - set ldisc on a tty 27396fd7ce5SGreg Kroah-Hartman * @tty: tty to assign 27496fd7ce5SGreg Kroah-Hartman * @ld: line discipline 27596fd7ce5SGreg Kroah-Hartman * 27696fd7ce5SGreg Kroah-Hartman * Install an instance of a line discipline into a tty structure. The 27796fd7ce5SGreg Kroah-Hartman * ldisc must have a reference count above zero to ensure it remains. 27896fd7ce5SGreg Kroah-Hartman * The tty instance refcount starts at zero. 27996fd7ce5SGreg Kroah-Hartman * 28096fd7ce5SGreg Kroah-Hartman * Locking: 28196fd7ce5SGreg Kroah-Hartman * Caller must hold references 28296fd7ce5SGreg Kroah-Hartman */ 28396fd7ce5SGreg Kroah-Hartman 28496fd7ce5SGreg Kroah-Hartman static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) 28596fd7ce5SGreg Kroah-Hartman { 28696fd7ce5SGreg Kroah-Hartman tty->ldisc = ld; 28796fd7ce5SGreg Kroah-Hartman } 28896fd7ce5SGreg Kroah-Hartman 28996fd7ce5SGreg Kroah-Hartman /** 29096fd7ce5SGreg Kroah-Hartman * tty_ldisc_try - internal helper 29196fd7ce5SGreg Kroah-Hartman * @tty: the tty 29296fd7ce5SGreg Kroah-Hartman * 29396fd7ce5SGreg Kroah-Hartman * Make a single attempt to grab and bump the refcount on 29496fd7ce5SGreg Kroah-Hartman * the tty ldisc. Return 0 on failure or 1 on success. This is 29596fd7ce5SGreg Kroah-Hartman * used to implement both the waiting and non waiting versions 29696fd7ce5SGreg Kroah-Hartman * of tty_ldisc_ref 29796fd7ce5SGreg Kroah-Hartman * 29896fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 29996fd7ce5SGreg Kroah-Hartman */ 30096fd7ce5SGreg Kroah-Hartman 30196fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_try(struct tty_struct *tty) 30296fd7ce5SGreg Kroah-Hartman { 30396fd7ce5SGreg Kroah-Hartman unsigned long flags; 30496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 30596fd7ce5SGreg Kroah-Hartman 30696fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 30796fd7ce5SGreg Kroah-Hartman ld = NULL; 30896fd7ce5SGreg Kroah-Hartman if (test_bit(TTY_LDISC, &tty->flags)) 30996fd7ce5SGreg Kroah-Hartman ld = get_ldisc(tty->ldisc); 31096fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 31196fd7ce5SGreg Kroah-Hartman return ld; 31296fd7ce5SGreg Kroah-Hartman } 31396fd7ce5SGreg Kroah-Hartman 31496fd7ce5SGreg Kroah-Hartman /** 31596fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 31696fd7ce5SGreg Kroah-Hartman * @tty: tty device 31796fd7ce5SGreg Kroah-Hartman * 31896fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 31996fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 32096fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 32196fd7ce5SGreg Kroah-Hartman * 32296fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 32396fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 32496fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 32596fd7ce5SGreg Kroah-Hartman * (which we check for) 32696fd7ce5SGreg Kroah-Hartman * 32796fd7ce5SGreg Kroah-Hartman * Locking: call functions take tty_ldisc_lock 32896fd7ce5SGreg Kroah-Hartman */ 32996fd7ce5SGreg Kroah-Hartman 33096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 33196fd7ce5SGreg Kroah-Hartman { 33296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 33396fd7ce5SGreg Kroah-Hartman 33496fd7ce5SGreg Kroah-Hartman /* wait_event is a macro */ 33596fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL); 33696fd7ce5SGreg Kroah-Hartman return ld; 33796fd7ce5SGreg Kroah-Hartman } 33896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 33996fd7ce5SGreg Kroah-Hartman 34096fd7ce5SGreg Kroah-Hartman /** 34196fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 34296fd7ce5SGreg Kroah-Hartman * @tty: tty device 34396fd7ce5SGreg Kroah-Hartman * 34496fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 34596fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 34696fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 34796fd7ce5SGreg Kroah-Hartman * 34896fd7ce5SGreg Kroah-Hartman * Locking: called functions take tty_ldisc_lock 34996fd7ce5SGreg Kroah-Hartman */ 35096fd7ce5SGreg Kroah-Hartman 35196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 35296fd7ce5SGreg Kroah-Hartman { 35396fd7ce5SGreg Kroah-Hartman return tty_ldisc_try(tty); 35496fd7ce5SGreg Kroah-Hartman } 35596fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 35696fd7ce5SGreg Kroah-Hartman 35796fd7ce5SGreg Kroah-Hartman /** 35896fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 35996fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 36096fd7ce5SGreg Kroah-Hartman * 36196fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 36296fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 36396fd7ce5SGreg Kroah-Hartman * 36496fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 36596fd7ce5SGreg Kroah-Hartman */ 36696fd7ce5SGreg Kroah-Hartman 36796fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 36896fd7ce5SGreg Kroah-Hartman { 36996fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 37096fd7ce5SGreg Kroah-Hartman } 37196fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 37296fd7ce5SGreg Kroah-Hartman 37396fd7ce5SGreg Kroah-Hartman static inline void tty_ldisc_put(struct tty_ldisc *ld) 37496fd7ce5SGreg Kroah-Hartman { 37596fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 37696fd7ce5SGreg Kroah-Hartman } 37796fd7ce5SGreg Kroah-Hartman 37896fd7ce5SGreg Kroah-Hartman /** 37996fd7ce5SGreg Kroah-Hartman * tty_ldisc_enable - allow ldisc use 38096fd7ce5SGreg Kroah-Hartman * @tty: terminal to activate ldisc on 38196fd7ce5SGreg Kroah-Hartman * 38296fd7ce5SGreg Kroah-Hartman * Set the TTY_LDISC flag when the line discipline can be called 38396fd7ce5SGreg Kroah-Hartman * again. Do necessary wakeups for existing sleepers. Clear the LDISC 38496fd7ce5SGreg Kroah-Hartman * changing flag to indicate any ldisc change is now over. 38596fd7ce5SGreg Kroah-Hartman * 38696fd7ce5SGreg Kroah-Hartman * Note: nobody should set the TTY_LDISC bit except via this function. 38796fd7ce5SGreg Kroah-Hartman * Clearing directly is allowed. 38896fd7ce5SGreg Kroah-Hartman */ 38996fd7ce5SGreg Kroah-Hartman 39096fd7ce5SGreg Kroah-Hartman void tty_ldisc_enable(struct tty_struct *tty) 39196fd7ce5SGreg Kroah-Hartman { 39296fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC, &tty->flags); 39396fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 39496fd7ce5SGreg Kroah-Hartman wake_up(&tty_ldisc_wait); 39596fd7ce5SGreg Kroah-Hartman } 39696fd7ce5SGreg Kroah-Hartman 39796fd7ce5SGreg Kroah-Hartman /** 39896fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 39996fd7ce5SGreg Kroah-Hartman * @tty: tty 40096fd7ce5SGreg Kroah-Hartman * 40196fd7ce5SGreg Kroah-Hartman * Flush the line discipline queue (if any) for this tty. If there 40296fd7ce5SGreg Kroah-Hartman * is no line discipline active this is a no-op. 40396fd7ce5SGreg Kroah-Hartman */ 40496fd7ce5SGreg Kroah-Hartman 40596fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 40696fd7ce5SGreg Kroah-Hartman { 40796fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 40896fd7ce5SGreg Kroah-Hartman if (ld) { 40996fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 41096fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 41196fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 41296fd7ce5SGreg Kroah-Hartman } 41396fd7ce5SGreg Kroah-Hartman tty_buffer_flush(tty); 41496fd7ce5SGreg Kroah-Hartman } 41596fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 41696fd7ce5SGreg Kroah-Hartman 41796fd7ce5SGreg Kroah-Hartman /** 41896fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 41996fd7ce5SGreg Kroah-Hartman * @tty: tty structure 42096fd7ce5SGreg Kroah-Hartman * @num: line discipline number 42196fd7ce5SGreg Kroah-Hartman * 42296fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 42396fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 42496fd7ce5SGreg Kroah-Hartman * any harm. 42596fd7ce5SGreg Kroah-Hartman * 42696fd7ce5SGreg Kroah-Hartman * Locking: takes termios_mutex 42796fd7ce5SGreg Kroah-Hartman */ 42896fd7ce5SGreg Kroah-Hartman 42996fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 43096fd7ce5SGreg Kroah-Hartman { 43196fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 43296fd7ce5SGreg Kroah-Hartman tty->termios->c_line = num; 43396fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 43496fd7ce5SGreg Kroah-Hartman } 43596fd7ce5SGreg Kroah-Hartman 43696fd7ce5SGreg Kroah-Hartman /** 43796fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 43896fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 43996fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 44096fd7ce5SGreg Kroah-Hartman * 44196fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 44296fd7ce5SGreg Kroah-Hartman * point. 44396fd7ce5SGreg Kroah-Hartman * 44496fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 44596fd7ce5SGreg Kroah-Hartman */ 44696fd7ce5SGreg Kroah-Hartman 44796fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 44896fd7ce5SGreg Kroah-Hartman { 44996fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 45096fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 45196fd7ce5SGreg Kroah-Hartman int ret; 45296fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 45396fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4547f90cfc5SJiri Slaby if (ret) 4557f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 45696fd7ce5SGreg Kroah-Hartman return ret; 45796fd7ce5SGreg Kroah-Hartman } 45896fd7ce5SGreg Kroah-Hartman return 0; 45996fd7ce5SGreg Kroah-Hartman } 46096fd7ce5SGreg Kroah-Hartman 46196fd7ce5SGreg Kroah-Hartman /** 46296fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 46396fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 46496fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 46596fd7ce5SGreg Kroah-Hartman * 46696fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 46796fd7ce5SGreg Kroah-Hartman * point. 46896fd7ce5SGreg Kroah-Hartman */ 46996fd7ce5SGreg Kroah-Hartman 47096fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 47196fd7ce5SGreg Kroah-Hartman { 47296fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 47396fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 47496fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 47596fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 47696fd7ce5SGreg Kroah-Hartman } 47796fd7ce5SGreg Kroah-Hartman 47896fd7ce5SGreg Kroah-Hartman /** 47996fd7ce5SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 48096fd7ce5SGreg Kroah-Hartman * @tty: tty to recover 48196fd7ce5SGreg Kroah-Hartman * @old: previous ldisc 48296fd7ce5SGreg Kroah-Hartman * 48396fd7ce5SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 48496fd7ce5SGreg Kroah-Hartman * change fails due to an open error 48596fd7ce5SGreg Kroah-Hartman */ 48696fd7ce5SGreg Kroah-Hartman 48796fd7ce5SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 48896fd7ce5SGreg Kroah-Hartman { 48996fd7ce5SGreg Kroah-Hartman char buf[64]; 49096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *new_ldisc; 49196fd7ce5SGreg Kroah-Hartman int r; 49296fd7ce5SGreg Kroah-Hartman 49396fd7ce5SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 49496fd7ce5SGreg Kroah-Hartman old = tty_ldisc_get(old->ops->num); 49596fd7ce5SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 49696fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, old); 49796fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 49896fd7ce5SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 49996fd7ce5SGreg Kroah-Hartman tty_ldisc_put(old); 50096fd7ce5SGreg Kroah-Hartman /* This driver is always present */ 50196fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(N_TTY); 50296fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 50396fd7ce5SGreg Kroah-Hartman panic("n_tty: get"); 50496fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 50596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 50696fd7ce5SGreg Kroah-Hartman r = tty_ldisc_open(tty, new_ldisc); 50796fd7ce5SGreg Kroah-Hartman if (r < 0) 50896fd7ce5SGreg Kroah-Hartman panic("Couldn't open N_TTY ldisc for " 50996fd7ce5SGreg Kroah-Hartman "%s --- error %d.", 51096fd7ce5SGreg Kroah-Hartman tty_name(tty, buf), r); 51196fd7ce5SGreg Kroah-Hartman } 51296fd7ce5SGreg Kroah-Hartman } 51396fd7ce5SGreg Kroah-Hartman 51496fd7ce5SGreg Kroah-Hartman /** 51596fd7ce5SGreg Kroah-Hartman * tty_ldisc_halt - shut down the line discipline 51696fd7ce5SGreg Kroah-Hartman * @tty: tty device 51796fd7ce5SGreg Kroah-Hartman * 51896fd7ce5SGreg Kroah-Hartman * Shut down the line discipline and work queue for this tty device. 51996fd7ce5SGreg Kroah-Hartman * The TTY_LDISC flag being cleared ensures no further references can 52096fd7ce5SGreg Kroah-Hartman * be obtained while the delayed work queue halt ensures that no more 52196fd7ce5SGreg Kroah-Hartman * data is fed to the ldisc. 52296fd7ce5SGreg Kroah-Hartman * 52396fd7ce5SGreg Kroah-Hartman * You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex) 52496fd7ce5SGreg Kroah-Hartman * in order to make sure any currently executing ldisc work is also 52596fd7ce5SGreg Kroah-Hartman * flushed. 52696fd7ce5SGreg Kroah-Hartman */ 52796fd7ce5SGreg Kroah-Hartman 52896fd7ce5SGreg Kroah-Hartman static int tty_ldisc_halt(struct tty_struct *tty) 52996fd7ce5SGreg Kroah-Hartman { 53096fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 531f23eb2b2SLinus Torvalds return cancel_work_sync(&tty->buf.work); 53296fd7ce5SGreg Kroah-Hartman } 53396fd7ce5SGreg Kroah-Hartman 53496fd7ce5SGreg Kroah-Hartman /** 5350a1f1a0bSTejun Heo * tty_ldisc_flush_works - flush all works of a tty 5360a1f1a0bSTejun Heo * @tty: tty device to flush works for 5370a1f1a0bSTejun Heo * 5380a1f1a0bSTejun Heo * Sync flush all works belonging to @tty. 5390a1f1a0bSTejun Heo */ 5400a1f1a0bSTejun Heo static void tty_ldisc_flush_works(struct tty_struct *tty) 5410a1f1a0bSTejun Heo { 5420a1f1a0bSTejun Heo flush_work_sync(&tty->hangup_work); 5430a1f1a0bSTejun Heo flush_work_sync(&tty->SAK_work); 544f23eb2b2SLinus Torvalds flush_work_sync(&tty->buf.work); 5450a1f1a0bSTejun Heo } 5460a1f1a0bSTejun Heo 5470a1f1a0bSTejun Heo /** 548100eeae2SJiri Slaby * tty_ldisc_wait_idle - wait for the ldisc to become idle 549100eeae2SJiri Slaby * @tty: tty to wait for 550df92d056SJiri Slaby * @timeout: for how long to wait at most 551100eeae2SJiri Slaby * 552100eeae2SJiri Slaby * Wait for the line discipline to become idle. The discipline must 553100eeae2SJiri Slaby * have been halted for this to guarantee it remains idle. 554100eeae2SJiri Slaby */ 555df92d056SJiri Slaby static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) 556100eeae2SJiri Slaby { 557df92d056SJiri Slaby long ret; 55892f6fa09SJiri Slaby ret = wait_event_timeout(tty_ldisc_idle, 559df92d056SJiri Slaby atomic_read(&tty->ldisc->users) == 1, timeout); 560100eeae2SJiri Slaby if (ret < 0) 561100eeae2SJiri Slaby return ret; 562100eeae2SJiri Slaby return ret > 0 ? 0 : -EBUSY; 563100eeae2SJiri Slaby } 564100eeae2SJiri Slaby 565100eeae2SJiri Slaby /** 56696fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 56796fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 56896fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 56996fd7ce5SGreg Kroah-Hartman * 57096fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 57196fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 57296fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 57396fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 57496fd7ce5SGreg Kroah-Hartman * 57596fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock, termios_mutex 57696fd7ce5SGreg Kroah-Hartman */ 57796fd7ce5SGreg Kroah-Hartman 57896fd7ce5SGreg Kroah-Hartman int tty_set_ldisc(struct tty_struct *tty, int ldisc) 57996fd7ce5SGreg Kroah-Hartman { 58096fd7ce5SGreg Kroah-Hartman int retval; 58196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *o_ldisc, *new_ldisc; 58296fd7ce5SGreg Kroah-Hartman int work, o_work = 0; 58396fd7ce5SGreg Kroah-Hartman struct tty_struct *o_tty; 58496fd7ce5SGreg Kroah-Hartman 58596fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(ldisc); 58696fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 58796fd7ce5SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 58896fd7ce5SGreg Kroah-Hartman 58996fd7ce5SGreg Kroah-Hartman tty_lock(); 59096fd7ce5SGreg Kroah-Hartman /* 59196fd7ce5SGreg Kroah-Hartman * We need to look at the tty locking here for pty/tty pairs 59296fd7ce5SGreg Kroah-Hartman * when both sides try to change in parallel. 59396fd7ce5SGreg Kroah-Hartman */ 59496fd7ce5SGreg Kroah-Hartman 59596fd7ce5SGreg Kroah-Hartman o_tty = tty->link; /* o_tty is the pty side or NULL */ 59696fd7ce5SGreg Kroah-Hartman 59796fd7ce5SGreg Kroah-Hartman 59896fd7ce5SGreg Kroah-Hartman /* 59996fd7ce5SGreg Kroah-Hartman * Check the no-op case 60096fd7ce5SGreg Kroah-Hartman */ 60196fd7ce5SGreg Kroah-Hartman 60296fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num == ldisc) { 60396fd7ce5SGreg Kroah-Hartman tty_unlock(); 60496fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 60596fd7ce5SGreg Kroah-Hartman return 0; 60696fd7ce5SGreg Kroah-Hartman } 60796fd7ce5SGreg Kroah-Hartman 60896fd7ce5SGreg Kroah-Hartman tty_unlock(); 60996fd7ce5SGreg Kroah-Hartman /* 61096fd7ce5SGreg Kroah-Hartman * Problem: What do we do if this blocks ? 61196fd7ce5SGreg Kroah-Hartman * We could deadlock here 61296fd7ce5SGreg Kroah-Hartman */ 61396fd7ce5SGreg Kroah-Hartman 61496fd7ce5SGreg Kroah-Hartman tty_wait_until_sent(tty, 0); 61596fd7ce5SGreg Kroah-Hartman 61696fd7ce5SGreg Kroah-Hartman tty_lock(); 61796fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 61896fd7ce5SGreg Kroah-Hartman 61996fd7ce5SGreg Kroah-Hartman /* 62096fd7ce5SGreg Kroah-Hartman * We could be midstream of another ldisc change which has 62196fd7ce5SGreg Kroah-Hartman * dropped the lock during processing. If so we need to wait. 62296fd7ce5SGreg Kroah-Hartman */ 62396fd7ce5SGreg Kroah-Hartman 62496fd7ce5SGreg Kroah-Hartman while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { 62596fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 62696fd7ce5SGreg Kroah-Hartman tty_unlock(); 62796fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, 62896fd7ce5SGreg Kroah-Hartman test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); 62996fd7ce5SGreg Kroah-Hartman tty_lock(); 63096fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 63196fd7ce5SGreg Kroah-Hartman } 63296fd7ce5SGreg Kroah-Hartman 63396fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC_CHANGING, &tty->flags); 63496fd7ce5SGreg Kroah-Hartman 63596fd7ce5SGreg Kroah-Hartman /* 63696fd7ce5SGreg Kroah-Hartman * No more input please, we are switching. The new ldisc 63796fd7ce5SGreg Kroah-Hartman * will update this value in the ldisc open function 63896fd7ce5SGreg Kroah-Hartman */ 63996fd7ce5SGreg Kroah-Hartman 64096fd7ce5SGreg Kroah-Hartman tty->receive_room = 0; 64196fd7ce5SGreg Kroah-Hartman 64296fd7ce5SGreg Kroah-Hartman o_ldisc = tty->ldisc; 64396fd7ce5SGreg Kroah-Hartman 64496fd7ce5SGreg Kroah-Hartman tty_unlock(); 64596fd7ce5SGreg Kroah-Hartman /* 64696fd7ce5SGreg Kroah-Hartman * Make sure we don't change while someone holds a 64796fd7ce5SGreg Kroah-Hartman * reference to the line discipline. The TTY_LDISC bit 64896fd7ce5SGreg Kroah-Hartman * prevents anyone taking a reference once it is clear. 64996fd7ce5SGreg Kroah-Hartman * We need the lock to avoid racing reference takers. 65096fd7ce5SGreg Kroah-Hartman * 65196fd7ce5SGreg Kroah-Hartman * We must clear the TTY_LDISC bit here to avoid a livelock 65296fd7ce5SGreg Kroah-Hartman * with a userspace app continually trying to use the tty in 65396fd7ce5SGreg Kroah-Hartman * parallel to the change and re-referencing the tty. 65496fd7ce5SGreg Kroah-Hartman */ 65596fd7ce5SGreg Kroah-Hartman 65696fd7ce5SGreg Kroah-Hartman work = tty_ldisc_halt(tty); 65796fd7ce5SGreg Kroah-Hartman if (o_tty) 65896fd7ce5SGreg Kroah-Hartman o_work = tty_ldisc_halt(o_tty); 65996fd7ce5SGreg Kroah-Hartman 66096fd7ce5SGreg Kroah-Hartman /* 66196fd7ce5SGreg Kroah-Hartman * Wait for ->hangup_work and ->buf.work handlers to terminate. 66296fd7ce5SGreg Kroah-Hartman * We must drop the mutex here in case a hangup is also in process. 66396fd7ce5SGreg Kroah-Hartman */ 66496fd7ce5SGreg Kroah-Hartman 66596fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 66696fd7ce5SGreg Kroah-Hartman 6670a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 66896fd7ce5SGreg Kroah-Hartman 669df92d056SJiri Slaby retval = tty_ldisc_wait_idle(tty, 5 * HZ); 670100eeae2SJiri Slaby 67196fd7ce5SGreg Kroah-Hartman tty_lock(); 67296fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 673100eeae2SJiri Slaby 674100eeae2SJiri Slaby /* handle wait idle failure locked */ 675100eeae2SJiri Slaby if (retval) { 676100eeae2SJiri Slaby tty_ldisc_put(new_ldisc); 677100eeae2SJiri Slaby goto enable; 678100eeae2SJiri Slaby } 679100eeae2SJiri Slaby 68096fd7ce5SGreg Kroah-Hartman if (test_bit(TTY_HUPPED, &tty->flags)) { 68196fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 68296fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 68396fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 68496fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 68596fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 68696fd7ce5SGreg Kroah-Hartman tty_unlock(); 68796fd7ce5SGreg Kroah-Hartman return -EIO; 68896fd7ce5SGreg Kroah-Hartman } 68996fd7ce5SGreg Kroah-Hartman 69096fd7ce5SGreg Kroah-Hartman /* Shutdown the current discipline. */ 69196fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, o_ldisc); 69296fd7ce5SGreg Kroah-Hartman 69396fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 69496fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 69596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 69696fd7ce5SGreg Kroah-Hartman 69796fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 69896fd7ce5SGreg Kroah-Hartman if (retval < 0) { 69996fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 70096fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 70196fd7ce5SGreg Kroah-Hartman tty_ldisc_restore(tty, o_ldisc); 70296fd7ce5SGreg Kroah-Hartman } 70396fd7ce5SGreg Kroah-Hartman 70496fd7ce5SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 70596fd7ce5SGreg Kroah-Hartman a reference to the old ldisc. If we ended up flipping back 70696fd7ce5SGreg Kroah-Hartman to the existing ldisc we have two references to it */ 70796fd7ce5SGreg Kroah-Hartman 70896fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc) 70996fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 71096fd7ce5SGreg Kroah-Hartman 71196fd7ce5SGreg Kroah-Hartman tty_ldisc_put(o_ldisc); 71296fd7ce5SGreg Kroah-Hartman 713100eeae2SJiri Slaby enable: 71496fd7ce5SGreg Kroah-Hartman /* 71596fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 71696fd7ce5SGreg Kroah-Hartman */ 71796fd7ce5SGreg Kroah-Hartman 71896fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 71996fd7ce5SGreg Kroah-Hartman if (o_tty) 72096fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 72196fd7ce5SGreg Kroah-Hartman 72296fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 72396fd7ce5SGreg Kroah-Hartman already running */ 72496fd7ce5SGreg Kroah-Hartman if (work) 725f23eb2b2SLinus Torvalds schedule_work(&tty->buf.work); 72696fd7ce5SGreg Kroah-Hartman if (o_work) 727f23eb2b2SLinus Torvalds schedule_work(&o_tty->buf.work); 72896fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 72996fd7ce5SGreg Kroah-Hartman tty_unlock(); 73096fd7ce5SGreg Kroah-Hartman return retval; 73196fd7ce5SGreg Kroah-Hartman } 73296fd7ce5SGreg Kroah-Hartman 73396fd7ce5SGreg Kroah-Hartman /** 73496fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 73596fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 73696fd7ce5SGreg Kroah-Hartman * 73796fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 73896fd7ce5SGreg Kroah-Hartman */ 73996fd7ce5SGreg Kroah-Hartman 74096fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 74196fd7ce5SGreg Kroah-Hartman { 74296fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 74396fd7ce5SGreg Kroah-Hartman *tty->termios = tty->driver->init_termios; 74496fd7ce5SGreg Kroah-Hartman tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); 74596fd7ce5SGreg Kroah-Hartman tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); 74696fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 74796fd7ce5SGreg Kroah-Hartman } 74896fd7ce5SGreg Kroah-Hartman 74996fd7ce5SGreg Kroah-Hartman 75096fd7ce5SGreg Kroah-Hartman /** 75196fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 75296fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 75396fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 75496fd7ce5SGreg Kroah-Hartman * 75596fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 75696fd7ce5SGreg Kroah-Hartman * state closed 75796fd7ce5SGreg Kroah-Hartman */ 75896fd7ce5SGreg Kroah-Hartman 7591c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 76096fd7ce5SGreg Kroah-Hartman { 7611c95ba1eSPhilippe Rétornaz struct tty_ldisc *ld = tty_ldisc_get(ldisc); 7621c95ba1eSPhilippe Rétornaz 7631c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 7641c95ba1eSPhilippe Rétornaz return -1; 76596fd7ce5SGreg Kroah-Hartman 766df92d056SJiri Slaby WARN_ON_ONCE(tty_ldisc_wait_idle(tty, 5 * HZ)); 76792f6fa09SJiri Slaby 76896fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 76996fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 77096fd7ce5SGreg Kroah-Hartman tty->ldisc = NULL; 77196fd7ce5SGreg Kroah-Hartman /* 77296fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 77396fd7ce5SGreg Kroah-Hartman */ 77496fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 77596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 7761c95ba1eSPhilippe Rétornaz 7771c95ba1eSPhilippe Rétornaz return 0; 77896fd7ce5SGreg Kroah-Hartman } 77996fd7ce5SGreg Kroah-Hartman 78096fd7ce5SGreg Kroah-Hartman /** 78196fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 78296fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 78396fd7ce5SGreg Kroah-Hartman * 78496fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 78596fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 78696fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 78796fd7ce5SGreg Kroah-Hartman * 78896fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 78996fd7ce5SGreg Kroah-Hartman * careful to allow for this. 79096fd7ce5SGreg Kroah-Hartman * 79196fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 79296fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 79396fd7ce5SGreg Kroah-Hartman */ 79496fd7ce5SGreg Kroah-Hartman 79596fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 79696fd7ce5SGreg Kroah-Hartman { 79796fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 79896fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 79996fd7ce5SGreg Kroah-Hartman int err = 0; 80096fd7ce5SGreg Kroah-Hartman 80196fd7ce5SGreg Kroah-Hartman /* 80296fd7ce5SGreg Kroah-Hartman * FIXME! What are the locking issues here? This may me overdoing 80396fd7ce5SGreg Kroah-Hartman * things... This question is especially important now that we've 80496fd7ce5SGreg Kroah-Hartman * removed the irqlock. 80596fd7ce5SGreg Kroah-Hartman */ 80696fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 80796fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 80896fd7ce5SGreg Kroah-Hartman /* We may have no line discipline at this point */ 80996fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 81096fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 81196fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 81296fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 81396fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 81496fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 81596fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 81696fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 81796fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 81896fd7ce5SGreg Kroah-Hartman } 81996fd7ce5SGreg Kroah-Hartman /* 82096fd7ce5SGreg Kroah-Hartman * FIXME: Once we trust the LDISC code better we can wait here for 82196fd7ce5SGreg Kroah-Hartman * ldisc completion and fix the driver call race 82296fd7ce5SGreg Kroah-Hartman */ 82396fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 82496fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 82596fd7ce5SGreg Kroah-Hartman /* 82696fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 82796fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 82896fd7ce5SGreg Kroah-Hartman * 82996fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 83096fd7ce5SGreg Kroah-Hartman */ 83196fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 83296fd7ce5SGreg Kroah-Hartman 83396fd7ce5SGreg Kroah-Hartman /* 83496fd7ce5SGreg Kroah-Hartman * this is like tty_ldisc_halt, but we need to give up 835f23eb2b2SLinus Torvalds * the BTM before calling cancel_work_sync, which may 836f23eb2b2SLinus Torvalds * need to wait for another function taking the BTM 83796fd7ce5SGreg Kroah-Hartman */ 83896fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 83996fd7ce5SGreg Kroah-Hartman tty_unlock(); 840f23eb2b2SLinus Torvalds cancel_work_sync(&tty->buf.work); 84196fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 84296fd7ce5SGreg Kroah-Hartman 84396fd7ce5SGreg Kroah-Hartman tty_lock(); 84496fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 84596fd7ce5SGreg Kroah-Hartman 84696fd7ce5SGreg Kroah-Hartman /* At this point we have a closed ldisc and we want to 84796fd7ce5SGreg Kroah-Hartman reopen it. We could defer this to the next open but 84896fd7ce5SGreg Kroah-Hartman it means auditing a lot of other paths so this is 84996fd7ce5SGreg Kroah-Hartman a FIXME */ 85096fd7ce5SGreg Kroah-Hartman if (tty->ldisc) { /* Not yet closed */ 85196fd7ce5SGreg Kroah-Hartman if (reset == 0) { 8521c95ba1eSPhilippe Rétornaz 8531c95ba1eSPhilippe Rétornaz if (!tty_ldisc_reinit(tty, tty->termios->c_line)) 85496fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 8551c95ba1eSPhilippe Rétornaz else 8561c95ba1eSPhilippe Rétornaz err = 1; 85796fd7ce5SGreg Kroah-Hartman } 85896fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 85996fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 86096fd7ce5SGreg Kroah-Hartman if (reset || err) { 8611c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 86296fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 86396fd7ce5SGreg Kroah-Hartman } 86496fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 86596fd7ce5SGreg Kroah-Hartman } 86696fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 86796fd7ce5SGreg Kroah-Hartman if (reset) 86896fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 86996fd7ce5SGreg Kroah-Hartman } 87096fd7ce5SGreg Kroah-Hartman 87196fd7ce5SGreg Kroah-Hartman /** 87296fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 87396fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 87496fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 87596fd7ce5SGreg Kroah-Hartman * 87696fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 87796fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 87896fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 87996fd7ce5SGreg Kroah-Hartman */ 88096fd7ce5SGreg Kroah-Hartman 88196fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 88296fd7ce5SGreg Kroah-Hartman { 88396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 88496fd7ce5SGreg Kroah-Hartman int retval; 88596fd7ce5SGreg Kroah-Hartman 88696fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 88796fd7ce5SGreg Kroah-Hartman if (retval) 88896fd7ce5SGreg Kroah-Hartman return retval; 88996fd7ce5SGreg Kroah-Hartman 89096fd7ce5SGreg Kroah-Hartman if (o_tty) { 89196fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 89296fd7ce5SGreg Kroah-Hartman if (retval) { 89396fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 89496fd7ce5SGreg Kroah-Hartman return retval; 89596fd7ce5SGreg Kroah-Hartman } 89696fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 89796fd7ce5SGreg Kroah-Hartman } 89896fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 89996fd7ce5SGreg Kroah-Hartman return 0; 90096fd7ce5SGreg Kroah-Hartman } 90196fd7ce5SGreg Kroah-Hartman /** 90296fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 90396fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 90496fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 90596fd7ce5SGreg Kroah-Hartman * 90696fd7ce5SGreg Kroah-Hartman * Called during the final close of a tty/pty pair in order to shut down 90796fd7ce5SGreg Kroah-Hartman * the line discpline layer. On exit the ldisc assigned is N_TTY and the 90896fd7ce5SGreg Kroah-Hartman * ldisc has not been opened. 90996fd7ce5SGreg Kroah-Hartman */ 91096fd7ce5SGreg Kroah-Hartman 91196fd7ce5SGreg Kroah-Hartman void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) 91296fd7ce5SGreg Kroah-Hartman { 91396fd7ce5SGreg Kroah-Hartman /* 91496fd7ce5SGreg Kroah-Hartman * Prevent flush_to_ldisc() from rescheduling the work for later. Then 91596fd7ce5SGreg Kroah-Hartman * kill any delayed work. As this is the final close it does not 91696fd7ce5SGreg Kroah-Hartman * race with the set_ldisc code path. 91796fd7ce5SGreg Kroah-Hartman */ 91896fd7ce5SGreg Kroah-Hartman 91996fd7ce5SGreg Kroah-Hartman tty_unlock(); 92096fd7ce5SGreg Kroah-Hartman tty_ldisc_halt(tty); 9210a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 92296fd7ce5SGreg Kroah-Hartman tty_lock(); 92396fd7ce5SGreg Kroah-Hartman 92496fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 92596fd7ce5SGreg Kroah-Hartman /* 92696fd7ce5SGreg Kroah-Hartman * Now kill off the ldisc 92796fd7ce5SGreg Kroah-Hartman */ 92896fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 92996fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 93096fd7ce5SGreg Kroah-Hartman /* Force an oops if we mess this up */ 93196fd7ce5SGreg Kroah-Hartman tty->ldisc = NULL; 93296fd7ce5SGreg Kroah-Hartman 93396fd7ce5SGreg Kroah-Hartman /* Ensure the next open requests the N_TTY ldisc */ 93496fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 93596fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 93696fd7ce5SGreg Kroah-Hartman 93796fd7ce5SGreg Kroah-Hartman /* This will need doing differently if we need to lock */ 93896fd7ce5SGreg Kroah-Hartman if (o_tty) 93996fd7ce5SGreg Kroah-Hartman tty_ldisc_release(o_tty, NULL); 94096fd7ce5SGreg Kroah-Hartman 94196fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 94296fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 94396fd7ce5SGreg Kroah-Hartman } 94496fd7ce5SGreg Kroah-Hartman 94596fd7ce5SGreg Kroah-Hartman /** 94696fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 94796fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 94896fd7ce5SGreg Kroah-Hartman * 94996fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 95096fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 95196fd7ce5SGreg Kroah-Hartman */ 95296fd7ce5SGreg Kroah-Hartman 95396fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 95496fd7ce5SGreg Kroah-Hartman { 95596fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_get(N_TTY); 95696fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 95796fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 95896fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 95996fd7ce5SGreg Kroah-Hartman } 96096fd7ce5SGreg Kroah-Hartman 9616716671dSJiri Slaby /** 9626716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 9636716671dSJiri Slaby * @tty: tty that was allocated recently 9646716671dSJiri Slaby * 9656716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 9666716671dSJiri Slaby * this call is made. 9676716671dSJiri Slaby */ 9686716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 9696716671dSJiri Slaby { 9706716671dSJiri Slaby put_ldisc(tty->ldisc); 9716716671dSJiri Slaby tty_ldisc_assign(tty, NULL); 9726716671dSJiri Slaby } 9736716671dSJiri Slaby 97496fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 97596fd7ce5SGreg Kroah-Hartman { 97696fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 97796fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 97896fd7ce5SGreg Kroah-Hartman } 979