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 2396fd7ce5SGreg Kroah-Hartman /* 2496fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 2596fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 2696fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 2796fd7ce5SGreg Kroah-Hartman */ 2896fd7ce5SGreg Kroah-Hartman 2996fd7ce5SGreg Kroah-Hartman static DEFINE_SPINLOCK(tty_ldisc_lock); 3096fd7ce5SGreg Kroah-Hartman static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); 3196fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 3296fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 3396fd7ce5SGreg Kroah-Hartman 3496fd7ce5SGreg Kroah-Hartman static inline struct tty_ldisc *get_ldisc(struct tty_ldisc *ld) 3596fd7ce5SGreg Kroah-Hartman { 3696fd7ce5SGreg Kroah-Hartman if (ld) 3796fd7ce5SGreg Kroah-Hartman atomic_inc(&ld->users); 3896fd7ce5SGreg Kroah-Hartman return ld; 3996fd7ce5SGreg Kroah-Hartman } 4096fd7ce5SGreg Kroah-Hartman 4196fd7ce5SGreg Kroah-Hartman static void put_ldisc(struct tty_ldisc *ld) 4296fd7ce5SGreg Kroah-Hartman { 4396fd7ce5SGreg Kroah-Hartman unsigned long flags; 4496fd7ce5SGreg Kroah-Hartman 4596fd7ce5SGreg Kroah-Hartman if (WARN_ON_ONCE(!ld)) 4696fd7ce5SGreg Kroah-Hartman return; 4796fd7ce5SGreg Kroah-Hartman 4896fd7ce5SGreg Kroah-Hartman /* 4996fd7ce5SGreg Kroah-Hartman * If this is the last user, free the ldisc, and 5096fd7ce5SGreg Kroah-Hartman * release the ldisc ops. 5196fd7ce5SGreg Kroah-Hartman * 5296fd7ce5SGreg Kroah-Hartman * We really want an "atomic_dec_and_lock_irqsave()", 5396fd7ce5SGreg Kroah-Hartman * but we don't have it, so this does it by hand. 5496fd7ce5SGreg Kroah-Hartman */ 5596fd7ce5SGreg Kroah-Hartman local_irq_save(flags); 5696fd7ce5SGreg Kroah-Hartman if (atomic_dec_and_lock(&ld->users, &tty_ldisc_lock)) { 5796fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldo = ld->ops; 5896fd7ce5SGreg Kroah-Hartman 5996fd7ce5SGreg Kroah-Hartman ldo->refcount--; 6096fd7ce5SGreg Kroah-Hartman module_put(ldo->owner); 6196fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 6296fd7ce5SGreg Kroah-Hartman 6396fd7ce5SGreg Kroah-Hartman kfree(ld); 6496fd7ce5SGreg Kroah-Hartman return; 6596fd7ce5SGreg Kroah-Hartman } 6696fd7ce5SGreg Kroah-Hartman local_irq_restore(flags); 671541f845SIvo Sieben wake_up(&ld->wq_idle); 6896fd7ce5SGreg Kroah-Hartman } 6996fd7ce5SGreg Kroah-Hartman 7096fd7ce5SGreg Kroah-Hartman /** 7196fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 7296fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 7396fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 7496fd7ce5SGreg Kroah-Hartman * 7596fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 7696fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 7796fd7ce5SGreg Kroah-Hartman * from this point onwards. 7896fd7ce5SGreg Kroah-Hartman * 7996fd7ce5SGreg Kroah-Hartman * Locking: 8096fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 8196fd7ce5SGreg Kroah-Hartman */ 8296fd7ce5SGreg Kroah-Hartman 8396fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 8496fd7ce5SGreg Kroah-Hartman { 8596fd7ce5SGreg Kroah-Hartman unsigned long flags; 8696fd7ce5SGreg Kroah-Hartman int ret = 0; 8796fd7ce5SGreg Kroah-Hartman 8896fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 8996fd7ce5SGreg Kroah-Hartman return -EINVAL; 9096fd7ce5SGreg Kroah-Hartman 9196fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 9296fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 9396fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 9496fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 9596fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 9696fd7ce5SGreg Kroah-Hartman 9796fd7ce5SGreg Kroah-Hartman return ret; 9896fd7ce5SGreg Kroah-Hartman } 9996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 10096fd7ce5SGreg Kroah-Hartman 10196fd7ce5SGreg Kroah-Hartman /** 10296fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 10396fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 10496fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 10596fd7ce5SGreg Kroah-Hartman * 10696fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 10796fd7ce5SGreg Kroah-Hartman * currently in use. 10896fd7ce5SGreg Kroah-Hartman * 10996fd7ce5SGreg Kroah-Hartman * Locking: 11096fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 11196fd7ce5SGreg Kroah-Hartman */ 11296fd7ce5SGreg Kroah-Hartman 11396fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 11496fd7ce5SGreg Kroah-Hartman { 11596fd7ce5SGreg Kroah-Hartman unsigned long flags; 11696fd7ce5SGreg Kroah-Hartman int ret = 0; 11796fd7ce5SGreg Kroah-Hartman 11896fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 11996fd7ce5SGreg Kroah-Hartman return -EINVAL; 12096fd7ce5SGreg Kroah-Hartman 12196fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 12296fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 12396fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 12496fd7ce5SGreg Kroah-Hartman else 12596fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 12696fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 12796fd7ce5SGreg Kroah-Hartman 12896fd7ce5SGreg Kroah-Hartman return ret; 12996fd7ce5SGreg Kroah-Hartman } 13096fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 13196fd7ce5SGreg Kroah-Hartman 13296fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 13396fd7ce5SGreg Kroah-Hartman { 13496fd7ce5SGreg Kroah-Hartman unsigned long flags; 13596fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 13696fd7ce5SGreg Kroah-Hartman 13796fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 13896fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 13996fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 14096fd7ce5SGreg Kroah-Hartman if (ldops) { 14196fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 14296fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 14396fd7ce5SGreg Kroah-Hartman ldops->refcount++; 14496fd7ce5SGreg Kroah-Hartman ret = ldops; 14596fd7ce5SGreg Kroah-Hartman } 14696fd7ce5SGreg Kroah-Hartman } 14796fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 14896fd7ce5SGreg Kroah-Hartman return ret; 14996fd7ce5SGreg Kroah-Hartman } 15096fd7ce5SGreg Kroah-Hartman 15196fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 15296fd7ce5SGreg Kroah-Hartman { 15396fd7ce5SGreg Kroah-Hartman unsigned long flags; 15496fd7ce5SGreg Kroah-Hartman 15596fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 15696fd7ce5SGreg Kroah-Hartman ldops->refcount--; 15796fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 15896fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 15996fd7ce5SGreg Kroah-Hartman } 16096fd7ce5SGreg Kroah-Hartman 16196fd7ce5SGreg Kroah-Hartman /** 16296fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 16396fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 16496fd7ce5SGreg Kroah-Hartman * 16596fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 16696fd7ce5SGreg Kroah-Hartman * module locking counts. Returns NULL if the discipline is not available. 16796fd7ce5SGreg Kroah-Hartman * Returns a pointer to the discipline and bumps the ref count if it is 16896fd7ce5SGreg Kroah-Hartman * available 16996fd7ce5SGreg Kroah-Hartman * 17096fd7ce5SGreg Kroah-Hartman * Locking: 17196fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 17296fd7ce5SGreg Kroah-Hartman */ 17396fd7ce5SGreg Kroah-Hartman 17496fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_get(int disc) 17596fd7ce5SGreg Kroah-Hartman { 17696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 17796fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 17896fd7ce5SGreg Kroah-Hartman 17996fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 18096fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 18196fd7ce5SGreg Kroah-Hartman 18296fd7ce5SGreg Kroah-Hartman /* 18396fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 18496fd7ce5SGreg Kroah-Hartman * dynamically and try again. 18596fd7ce5SGreg Kroah-Hartman */ 18696fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 18796fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 18896fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 18996fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 19096fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 19196fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 19296fd7ce5SGreg Kroah-Hartman } 19396fd7ce5SGreg Kroah-Hartman 19496fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 19596fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 19696fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 19796fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 19896fd7ce5SGreg Kroah-Hartman } 19996fd7ce5SGreg Kroah-Hartman 20096fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 20196fd7ce5SGreg Kroah-Hartman atomic_set(&ld->users, 1); 2021541f845SIvo Sieben init_waitqueue_head(&ld->wq_idle); 2031541f845SIvo Sieben 20496fd7ce5SGreg Kroah-Hartman return ld; 20596fd7ce5SGreg Kroah-Hartman } 20696fd7ce5SGreg Kroah-Hartman 20796fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 20896fd7ce5SGreg Kroah-Hartman { 20996fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 21096fd7ce5SGreg Kroah-Hartman } 21196fd7ce5SGreg Kroah-Hartman 21296fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 21396fd7ce5SGreg Kroah-Hartman { 21496fd7ce5SGreg Kroah-Hartman (*pos)++; 21596fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 21696fd7ce5SGreg Kroah-Hartman } 21796fd7ce5SGreg Kroah-Hartman 21896fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 21996fd7ce5SGreg Kroah-Hartman { 22096fd7ce5SGreg Kroah-Hartman } 22196fd7ce5SGreg Kroah-Hartman 22296fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 22396fd7ce5SGreg Kroah-Hartman { 22496fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 22596fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 22696fd7ce5SGreg Kroah-Hartman 22796fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 22896fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 22996fd7ce5SGreg Kroah-Hartman return 0; 23096fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 23196fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 23296fd7ce5SGreg Kroah-Hartman return 0; 23396fd7ce5SGreg Kroah-Hartman } 23496fd7ce5SGreg Kroah-Hartman 23596fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 23696fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 23796fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 23896fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 23996fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 24096fd7ce5SGreg Kroah-Hartman }; 24196fd7ce5SGreg Kroah-Hartman 24296fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 24396fd7ce5SGreg Kroah-Hartman { 24496fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 24596fd7ce5SGreg Kroah-Hartman } 24696fd7ce5SGreg Kroah-Hartman 24796fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 24896fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 24996fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 25096fd7ce5SGreg Kroah-Hartman .read = seq_read, 25196fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 25296fd7ce5SGreg Kroah-Hartman .release = seq_release, 25396fd7ce5SGreg Kroah-Hartman }; 25496fd7ce5SGreg Kroah-Hartman 25596fd7ce5SGreg Kroah-Hartman /** 25696fd7ce5SGreg Kroah-Hartman * tty_ldisc_assign - set ldisc on a tty 25796fd7ce5SGreg Kroah-Hartman * @tty: tty to assign 25896fd7ce5SGreg Kroah-Hartman * @ld: line discipline 25996fd7ce5SGreg Kroah-Hartman * 26096fd7ce5SGreg Kroah-Hartman * Install an instance of a line discipline into a tty structure. The 26196fd7ce5SGreg Kroah-Hartman * ldisc must have a reference count above zero to ensure it remains. 26296fd7ce5SGreg Kroah-Hartman * The tty instance refcount starts at zero. 26396fd7ce5SGreg Kroah-Hartman * 26496fd7ce5SGreg Kroah-Hartman * Locking: 26596fd7ce5SGreg Kroah-Hartman * Caller must hold references 26696fd7ce5SGreg Kroah-Hartman */ 26796fd7ce5SGreg Kroah-Hartman 26896fd7ce5SGreg Kroah-Hartman static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) 26996fd7ce5SGreg Kroah-Hartman { 27096fd7ce5SGreg Kroah-Hartman tty->ldisc = ld; 27196fd7ce5SGreg Kroah-Hartman } 27296fd7ce5SGreg Kroah-Hartman 27396fd7ce5SGreg Kroah-Hartman /** 27496fd7ce5SGreg Kroah-Hartman * tty_ldisc_try - internal helper 27596fd7ce5SGreg Kroah-Hartman * @tty: the tty 27696fd7ce5SGreg Kroah-Hartman * 27796fd7ce5SGreg Kroah-Hartman * Make a single attempt to grab and bump the refcount on 27896fd7ce5SGreg Kroah-Hartman * the tty ldisc. Return 0 on failure or 1 on success. This is 27996fd7ce5SGreg Kroah-Hartman * used to implement both the waiting and non waiting versions 28096fd7ce5SGreg Kroah-Hartman * of tty_ldisc_ref 28196fd7ce5SGreg Kroah-Hartman * 28296fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 28396fd7ce5SGreg Kroah-Hartman */ 28496fd7ce5SGreg Kroah-Hartman 28596fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_try(struct tty_struct *tty) 28696fd7ce5SGreg Kroah-Hartman { 28796fd7ce5SGreg Kroah-Hartman unsigned long flags; 28896fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 28996fd7ce5SGreg Kroah-Hartman 29096fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 29196fd7ce5SGreg Kroah-Hartman ld = NULL; 29296fd7ce5SGreg Kroah-Hartman if (test_bit(TTY_LDISC, &tty->flags)) 29396fd7ce5SGreg Kroah-Hartman ld = get_ldisc(tty->ldisc); 29496fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 29596fd7ce5SGreg Kroah-Hartman return ld; 29696fd7ce5SGreg Kroah-Hartman } 29796fd7ce5SGreg Kroah-Hartman 29896fd7ce5SGreg Kroah-Hartman /** 29996fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 30096fd7ce5SGreg Kroah-Hartman * @tty: tty device 30196fd7ce5SGreg Kroah-Hartman * 30296fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 30396fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 30496fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 30596fd7ce5SGreg Kroah-Hartman * 30696fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 30796fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 30896fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 30996fd7ce5SGreg Kroah-Hartman * (which we check for) 31096fd7ce5SGreg Kroah-Hartman * 31196fd7ce5SGreg Kroah-Hartman * Locking: call functions take tty_ldisc_lock 31296fd7ce5SGreg Kroah-Hartman */ 31396fd7ce5SGreg Kroah-Hartman 31496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 31596fd7ce5SGreg Kroah-Hartman { 31696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 31796fd7ce5SGreg Kroah-Hartman 31896fd7ce5SGreg Kroah-Hartman /* wait_event is a macro */ 31996fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL); 32096fd7ce5SGreg Kroah-Hartman return ld; 32196fd7ce5SGreg Kroah-Hartman } 32296fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 32396fd7ce5SGreg Kroah-Hartman 32496fd7ce5SGreg Kroah-Hartman /** 32596fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 32696fd7ce5SGreg Kroah-Hartman * @tty: tty device 32796fd7ce5SGreg Kroah-Hartman * 32896fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 32996fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 33096fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 33196fd7ce5SGreg Kroah-Hartman * 33296fd7ce5SGreg Kroah-Hartman * Locking: called functions take tty_ldisc_lock 33396fd7ce5SGreg Kroah-Hartman */ 33496fd7ce5SGreg Kroah-Hartman 33596fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 33696fd7ce5SGreg Kroah-Hartman { 33796fd7ce5SGreg Kroah-Hartman return tty_ldisc_try(tty); 33896fd7ce5SGreg Kroah-Hartman } 33996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 34096fd7ce5SGreg Kroah-Hartman 34196fd7ce5SGreg Kroah-Hartman /** 34296fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 34396fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 34496fd7ce5SGreg Kroah-Hartman * 34596fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 34696fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 34796fd7ce5SGreg Kroah-Hartman * 34896fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 34996fd7ce5SGreg Kroah-Hartman */ 35096fd7ce5SGreg Kroah-Hartman 35196fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 35296fd7ce5SGreg Kroah-Hartman { 35396fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 35496fd7ce5SGreg Kroah-Hartman } 35596fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 35696fd7ce5SGreg Kroah-Hartman 35796fd7ce5SGreg Kroah-Hartman static inline void tty_ldisc_put(struct tty_ldisc *ld) 35896fd7ce5SGreg Kroah-Hartman { 35996fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 36096fd7ce5SGreg Kroah-Hartman } 36196fd7ce5SGreg Kroah-Hartman 36296fd7ce5SGreg Kroah-Hartman /** 36396fd7ce5SGreg Kroah-Hartman * tty_ldisc_enable - allow ldisc use 36496fd7ce5SGreg Kroah-Hartman * @tty: terminal to activate ldisc on 36596fd7ce5SGreg Kroah-Hartman * 36696fd7ce5SGreg Kroah-Hartman * Set the TTY_LDISC flag when the line discipline can be called 36796fd7ce5SGreg Kroah-Hartman * again. Do necessary wakeups for existing sleepers. Clear the LDISC 36896fd7ce5SGreg Kroah-Hartman * changing flag to indicate any ldisc change is now over. 36996fd7ce5SGreg Kroah-Hartman * 37096fd7ce5SGreg Kroah-Hartman * Note: nobody should set the TTY_LDISC bit except via this function. 37196fd7ce5SGreg Kroah-Hartman * Clearing directly is allowed. 37296fd7ce5SGreg Kroah-Hartman */ 37396fd7ce5SGreg Kroah-Hartman 37496fd7ce5SGreg Kroah-Hartman void tty_ldisc_enable(struct tty_struct *tty) 37596fd7ce5SGreg Kroah-Hartman { 37696fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC, &tty->flags); 37796fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 37896fd7ce5SGreg Kroah-Hartman wake_up(&tty_ldisc_wait); 37996fd7ce5SGreg Kroah-Hartman } 38096fd7ce5SGreg Kroah-Hartman 38196fd7ce5SGreg Kroah-Hartman /** 38296fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 38396fd7ce5SGreg Kroah-Hartman * @tty: tty 38496fd7ce5SGreg Kroah-Hartman * 38596fd7ce5SGreg Kroah-Hartman * Flush the line discipline queue (if any) for this tty. If there 38696fd7ce5SGreg Kroah-Hartman * is no line discipline active this is a no-op. 38796fd7ce5SGreg Kroah-Hartman */ 38896fd7ce5SGreg Kroah-Hartman 38996fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 39096fd7ce5SGreg Kroah-Hartman { 39196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 39296fd7ce5SGreg Kroah-Hartman if (ld) { 39396fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 39496fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 39596fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 39696fd7ce5SGreg Kroah-Hartman } 39796fd7ce5SGreg Kroah-Hartman tty_buffer_flush(tty); 39896fd7ce5SGreg Kroah-Hartman } 39996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 40096fd7ce5SGreg Kroah-Hartman 40196fd7ce5SGreg Kroah-Hartman /** 40296fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 40396fd7ce5SGreg Kroah-Hartman * @tty: tty structure 40496fd7ce5SGreg Kroah-Hartman * @num: line discipline number 40596fd7ce5SGreg Kroah-Hartman * 40696fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 40796fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 40896fd7ce5SGreg Kroah-Hartman * any harm. 40996fd7ce5SGreg Kroah-Hartman * 41096fd7ce5SGreg Kroah-Hartman * Locking: takes termios_mutex 41196fd7ce5SGreg Kroah-Hartman */ 41296fd7ce5SGreg Kroah-Hartman 41396fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 41496fd7ce5SGreg Kroah-Hartman { 41596fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 41696fd7ce5SGreg Kroah-Hartman tty->termios->c_line = num; 41796fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 41896fd7ce5SGreg Kroah-Hartman } 41996fd7ce5SGreg Kroah-Hartman 42096fd7ce5SGreg Kroah-Hartman /** 42196fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 42296fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 42396fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 42496fd7ce5SGreg Kroah-Hartman * 42596fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 42696fd7ce5SGreg Kroah-Hartman * point. 42796fd7ce5SGreg Kroah-Hartman * 42896fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 42996fd7ce5SGreg Kroah-Hartman */ 43096fd7ce5SGreg Kroah-Hartman 43196fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 43296fd7ce5SGreg Kroah-Hartman { 43396fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 43496fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 43596fd7ce5SGreg Kroah-Hartman int ret; 43696fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 43796fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4387f90cfc5SJiri Slaby if (ret) 4397f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 44096fd7ce5SGreg Kroah-Hartman return ret; 44196fd7ce5SGreg Kroah-Hartman } 44296fd7ce5SGreg Kroah-Hartman return 0; 44396fd7ce5SGreg Kroah-Hartman } 44496fd7ce5SGreg Kroah-Hartman 44596fd7ce5SGreg Kroah-Hartman /** 44696fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 44796fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 44896fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 44996fd7ce5SGreg Kroah-Hartman * 45096fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 45196fd7ce5SGreg Kroah-Hartman * point. 45296fd7ce5SGreg Kroah-Hartman */ 45396fd7ce5SGreg Kroah-Hartman 45496fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 45596fd7ce5SGreg Kroah-Hartman { 45696fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 45796fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 45896fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 45996fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 46096fd7ce5SGreg Kroah-Hartman } 46196fd7ce5SGreg Kroah-Hartman 46296fd7ce5SGreg Kroah-Hartman /** 46396fd7ce5SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 46496fd7ce5SGreg Kroah-Hartman * @tty: tty to recover 46596fd7ce5SGreg Kroah-Hartman * @old: previous ldisc 46696fd7ce5SGreg Kroah-Hartman * 46796fd7ce5SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 46896fd7ce5SGreg Kroah-Hartman * change fails due to an open error 46996fd7ce5SGreg Kroah-Hartman */ 47096fd7ce5SGreg Kroah-Hartman 47196fd7ce5SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 47296fd7ce5SGreg Kroah-Hartman { 47396fd7ce5SGreg Kroah-Hartman char buf[64]; 47496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *new_ldisc; 47596fd7ce5SGreg Kroah-Hartman int r; 47696fd7ce5SGreg Kroah-Hartman 47796fd7ce5SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 47896fd7ce5SGreg Kroah-Hartman old = tty_ldisc_get(old->ops->num); 47996fd7ce5SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 48096fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, old); 48196fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 48296fd7ce5SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 48396fd7ce5SGreg Kroah-Hartman tty_ldisc_put(old); 48496fd7ce5SGreg Kroah-Hartman /* This driver is always present */ 48596fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(N_TTY); 48696fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 48796fd7ce5SGreg Kroah-Hartman panic("n_tty: get"); 48896fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 48996fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 49096fd7ce5SGreg Kroah-Hartman r = tty_ldisc_open(tty, new_ldisc); 49196fd7ce5SGreg Kroah-Hartman if (r < 0) 49296fd7ce5SGreg Kroah-Hartman panic("Couldn't open N_TTY ldisc for " 49396fd7ce5SGreg Kroah-Hartman "%s --- error %d.", 49496fd7ce5SGreg Kroah-Hartman tty_name(tty, buf), r); 49596fd7ce5SGreg Kroah-Hartman } 49696fd7ce5SGreg Kroah-Hartman } 49796fd7ce5SGreg Kroah-Hartman 49896fd7ce5SGreg Kroah-Hartman /** 49996fd7ce5SGreg Kroah-Hartman * tty_ldisc_halt - shut down the line discipline 50096fd7ce5SGreg Kroah-Hartman * @tty: tty device 50196fd7ce5SGreg Kroah-Hartman * 50296fd7ce5SGreg Kroah-Hartman * Shut down the line discipline and work queue for this tty device. 50396fd7ce5SGreg Kroah-Hartman * The TTY_LDISC flag being cleared ensures no further references can 50496fd7ce5SGreg Kroah-Hartman * be obtained while the delayed work queue halt ensures that no more 50596fd7ce5SGreg Kroah-Hartman * data is fed to the ldisc. 50696fd7ce5SGreg Kroah-Hartman * 50796fd7ce5SGreg Kroah-Hartman * You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex) 50896fd7ce5SGreg Kroah-Hartman * in order to make sure any currently executing ldisc work is also 50996fd7ce5SGreg Kroah-Hartman * flushed. 51096fd7ce5SGreg Kroah-Hartman */ 51196fd7ce5SGreg Kroah-Hartman 51296fd7ce5SGreg Kroah-Hartman static int tty_ldisc_halt(struct tty_struct *tty) 51396fd7ce5SGreg Kroah-Hartman { 51496fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 515f23eb2b2SLinus Torvalds return cancel_work_sync(&tty->buf.work); 51696fd7ce5SGreg Kroah-Hartman } 51796fd7ce5SGreg Kroah-Hartman 51896fd7ce5SGreg Kroah-Hartman /** 5190a1f1a0bSTejun Heo * tty_ldisc_flush_works - flush all works of a tty 5200a1f1a0bSTejun Heo * @tty: tty device to flush works for 5210a1f1a0bSTejun Heo * 5220a1f1a0bSTejun Heo * Sync flush all works belonging to @tty. 5230a1f1a0bSTejun Heo */ 5240a1f1a0bSTejun Heo static void tty_ldisc_flush_works(struct tty_struct *tty) 5250a1f1a0bSTejun Heo { 5260a1f1a0bSTejun Heo flush_work_sync(&tty->hangup_work); 5270a1f1a0bSTejun Heo flush_work_sync(&tty->SAK_work); 528f23eb2b2SLinus Torvalds flush_work_sync(&tty->buf.work); 5290a1f1a0bSTejun Heo } 5300a1f1a0bSTejun Heo 5310a1f1a0bSTejun Heo /** 532100eeae2SJiri Slaby * tty_ldisc_wait_idle - wait for the ldisc to become idle 533100eeae2SJiri Slaby * @tty: tty to wait for 534df92d056SJiri Slaby * @timeout: for how long to wait at most 535100eeae2SJiri Slaby * 536100eeae2SJiri Slaby * Wait for the line discipline to become idle. The discipline must 537100eeae2SJiri Slaby * have been halted for this to guarantee it remains idle. 538100eeae2SJiri Slaby */ 539df92d056SJiri Slaby static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) 540100eeae2SJiri Slaby { 541df92d056SJiri Slaby long ret; 5421541f845SIvo Sieben ret = wait_event_timeout(tty->ldisc->wq_idle, 543df92d056SJiri Slaby atomic_read(&tty->ldisc->users) == 1, timeout); 544100eeae2SJiri Slaby return ret > 0 ? 0 : -EBUSY; 545100eeae2SJiri Slaby } 546100eeae2SJiri Slaby 547100eeae2SJiri Slaby /** 54896fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 54996fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 55096fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 55196fd7ce5SGreg Kroah-Hartman * 55296fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 55396fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 55496fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 55596fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 55696fd7ce5SGreg Kroah-Hartman * 55796fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock, termios_mutex 55896fd7ce5SGreg Kroah-Hartman */ 55996fd7ce5SGreg Kroah-Hartman 56096fd7ce5SGreg Kroah-Hartman int tty_set_ldisc(struct tty_struct *tty, int ldisc) 56196fd7ce5SGreg Kroah-Hartman { 56296fd7ce5SGreg Kroah-Hartman int retval; 56396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *o_ldisc, *new_ldisc; 56496fd7ce5SGreg Kroah-Hartman int work, o_work = 0; 56596fd7ce5SGreg Kroah-Hartman struct tty_struct *o_tty; 56696fd7ce5SGreg Kroah-Hartman 56796fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(ldisc); 56896fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 56996fd7ce5SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 57096fd7ce5SGreg Kroah-Hartman 571f5e3bcc5SAlan Cox tty_lock(tty); 57296fd7ce5SGreg Kroah-Hartman /* 57396fd7ce5SGreg Kroah-Hartman * We need to look at the tty locking here for pty/tty pairs 57496fd7ce5SGreg Kroah-Hartman * when both sides try to change in parallel. 57596fd7ce5SGreg Kroah-Hartman */ 57696fd7ce5SGreg Kroah-Hartman 57796fd7ce5SGreg Kroah-Hartman o_tty = tty->link; /* o_tty is the pty side or NULL */ 57896fd7ce5SGreg Kroah-Hartman 57996fd7ce5SGreg Kroah-Hartman 58096fd7ce5SGreg Kroah-Hartman /* 58196fd7ce5SGreg Kroah-Hartman * Check the no-op case 58296fd7ce5SGreg Kroah-Hartman */ 58396fd7ce5SGreg Kroah-Hartman 58496fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num == ldisc) { 585f5e3bcc5SAlan Cox tty_unlock(tty); 58696fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 58796fd7ce5SGreg Kroah-Hartman return 0; 58896fd7ce5SGreg Kroah-Hartman } 58996fd7ce5SGreg Kroah-Hartman 590f5e3bcc5SAlan Cox tty_unlock(tty); 59196fd7ce5SGreg Kroah-Hartman /* 59296fd7ce5SGreg Kroah-Hartman * Problem: What do we do if this blocks ? 59396fd7ce5SGreg Kroah-Hartman * We could deadlock here 59496fd7ce5SGreg Kroah-Hartman */ 59596fd7ce5SGreg Kroah-Hartman 59696fd7ce5SGreg Kroah-Hartman tty_wait_until_sent(tty, 0); 59796fd7ce5SGreg Kroah-Hartman 598f5e3bcc5SAlan Cox tty_lock(tty); 59996fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 60096fd7ce5SGreg Kroah-Hartman 60196fd7ce5SGreg Kroah-Hartman /* 60296fd7ce5SGreg Kroah-Hartman * We could be midstream of another ldisc change which has 60396fd7ce5SGreg Kroah-Hartman * dropped the lock during processing. If so we need to wait. 60496fd7ce5SGreg Kroah-Hartman */ 60596fd7ce5SGreg Kroah-Hartman 60696fd7ce5SGreg Kroah-Hartman while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { 60796fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 608f5e3bcc5SAlan Cox tty_unlock(tty); 60996fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, 61096fd7ce5SGreg Kroah-Hartman test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); 611f5e3bcc5SAlan Cox tty_lock(tty); 61296fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 61396fd7ce5SGreg Kroah-Hartman } 61496fd7ce5SGreg Kroah-Hartman 61596fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC_CHANGING, &tty->flags); 61696fd7ce5SGreg Kroah-Hartman 61796fd7ce5SGreg Kroah-Hartman /* 61896fd7ce5SGreg Kroah-Hartman * No more input please, we are switching. The new ldisc 61996fd7ce5SGreg Kroah-Hartman * will update this value in the ldisc open function 62096fd7ce5SGreg Kroah-Hartman */ 62196fd7ce5SGreg Kroah-Hartman 62296fd7ce5SGreg Kroah-Hartman tty->receive_room = 0; 62396fd7ce5SGreg Kroah-Hartman 62496fd7ce5SGreg Kroah-Hartman o_ldisc = tty->ldisc; 62596fd7ce5SGreg Kroah-Hartman 626f5e3bcc5SAlan Cox tty_unlock(tty); 62796fd7ce5SGreg Kroah-Hartman /* 62896fd7ce5SGreg Kroah-Hartman * Make sure we don't change while someone holds a 62996fd7ce5SGreg Kroah-Hartman * reference to the line discipline. The TTY_LDISC bit 63096fd7ce5SGreg Kroah-Hartman * prevents anyone taking a reference once it is clear. 63196fd7ce5SGreg Kroah-Hartman * We need the lock to avoid racing reference takers. 63296fd7ce5SGreg Kroah-Hartman * 63396fd7ce5SGreg Kroah-Hartman * We must clear the TTY_LDISC bit here to avoid a livelock 63496fd7ce5SGreg Kroah-Hartman * with a userspace app continually trying to use the tty in 63596fd7ce5SGreg Kroah-Hartman * parallel to the change and re-referencing the tty. 63696fd7ce5SGreg Kroah-Hartman */ 63796fd7ce5SGreg Kroah-Hartman 63896fd7ce5SGreg Kroah-Hartman work = tty_ldisc_halt(tty); 63996fd7ce5SGreg Kroah-Hartman if (o_tty) 64096fd7ce5SGreg Kroah-Hartman o_work = tty_ldisc_halt(o_tty); 64196fd7ce5SGreg Kroah-Hartman 64296fd7ce5SGreg Kroah-Hartman /* 64396fd7ce5SGreg Kroah-Hartman * Wait for ->hangup_work and ->buf.work handlers to terminate. 64496fd7ce5SGreg Kroah-Hartman * We must drop the mutex here in case a hangup is also in process. 64596fd7ce5SGreg Kroah-Hartman */ 64696fd7ce5SGreg Kroah-Hartman 64796fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 64896fd7ce5SGreg Kroah-Hartman 6490a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 65096fd7ce5SGreg Kroah-Hartman 651df92d056SJiri Slaby retval = tty_ldisc_wait_idle(tty, 5 * HZ); 652100eeae2SJiri Slaby 653f5e3bcc5SAlan Cox tty_lock(tty); 65496fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 655100eeae2SJiri Slaby 656100eeae2SJiri Slaby /* handle wait idle failure locked */ 657100eeae2SJiri Slaby if (retval) { 658100eeae2SJiri Slaby tty_ldisc_put(new_ldisc); 659100eeae2SJiri Slaby goto enable; 660100eeae2SJiri Slaby } 661100eeae2SJiri Slaby 66240c9f61eSShachar Shemesh if (test_bit(TTY_HUPPING, &tty->flags)) { 66396fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 66496fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 66596fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 66696fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 66796fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 668f5e3bcc5SAlan Cox tty_unlock(tty); 66996fd7ce5SGreg Kroah-Hartman return -EIO; 67096fd7ce5SGreg Kroah-Hartman } 67196fd7ce5SGreg Kroah-Hartman 67296fd7ce5SGreg Kroah-Hartman /* Shutdown the current discipline. */ 67396fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, o_ldisc); 67496fd7ce5SGreg Kroah-Hartman 67596fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 67696fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 67796fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 67896fd7ce5SGreg Kroah-Hartman 67996fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 68096fd7ce5SGreg Kroah-Hartman if (retval < 0) { 68196fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 68296fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 68396fd7ce5SGreg Kroah-Hartman tty_ldisc_restore(tty, o_ldisc); 68496fd7ce5SGreg Kroah-Hartman } 68596fd7ce5SGreg Kroah-Hartman 68696fd7ce5SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 68796fd7ce5SGreg Kroah-Hartman a reference to the old ldisc. If we ended up flipping back 68896fd7ce5SGreg Kroah-Hartman to the existing ldisc we have two references to it */ 68996fd7ce5SGreg Kroah-Hartman 69096fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc) 69196fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 69296fd7ce5SGreg Kroah-Hartman 69396fd7ce5SGreg Kroah-Hartman tty_ldisc_put(o_ldisc); 69496fd7ce5SGreg Kroah-Hartman 695100eeae2SJiri Slaby enable: 69696fd7ce5SGreg Kroah-Hartman /* 69796fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 69896fd7ce5SGreg Kroah-Hartman */ 69996fd7ce5SGreg Kroah-Hartman 70096fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 70196fd7ce5SGreg Kroah-Hartman if (o_tty) 70296fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 70396fd7ce5SGreg Kroah-Hartman 70496fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 70596fd7ce5SGreg Kroah-Hartman already running */ 70696fd7ce5SGreg Kroah-Hartman if (work) 707f23eb2b2SLinus Torvalds schedule_work(&tty->buf.work); 70896fd7ce5SGreg Kroah-Hartman if (o_work) 709f23eb2b2SLinus Torvalds schedule_work(&o_tty->buf.work); 71096fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 711f5e3bcc5SAlan Cox tty_unlock(tty); 71296fd7ce5SGreg Kroah-Hartman return retval; 71396fd7ce5SGreg Kroah-Hartman } 71496fd7ce5SGreg Kroah-Hartman 71596fd7ce5SGreg Kroah-Hartman /** 71696fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 71796fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 71896fd7ce5SGreg Kroah-Hartman * 71996fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 72096fd7ce5SGreg Kroah-Hartman */ 72196fd7ce5SGreg Kroah-Hartman 72296fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 72396fd7ce5SGreg Kroah-Hartman { 72496fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 72596fd7ce5SGreg Kroah-Hartman *tty->termios = tty->driver->init_termios; 72696fd7ce5SGreg Kroah-Hartman tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); 72796fd7ce5SGreg Kroah-Hartman tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); 72896fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 72996fd7ce5SGreg Kroah-Hartman } 73096fd7ce5SGreg Kroah-Hartman 73196fd7ce5SGreg Kroah-Hartman 73296fd7ce5SGreg Kroah-Hartman /** 73396fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 73496fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 73596fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 73696fd7ce5SGreg Kroah-Hartman * 73796fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 73896fd7ce5SGreg Kroah-Hartman * state closed 73996fd7ce5SGreg Kroah-Hartman */ 74096fd7ce5SGreg Kroah-Hartman 7411c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 74296fd7ce5SGreg Kroah-Hartman { 7431c95ba1eSPhilippe Rétornaz struct tty_ldisc *ld = tty_ldisc_get(ldisc); 7441c95ba1eSPhilippe Rétornaz 7451c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 7461c95ba1eSPhilippe Rétornaz return -1; 74796fd7ce5SGreg Kroah-Hartman 74896fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 74996fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 75096fd7ce5SGreg Kroah-Hartman tty->ldisc = NULL; 75196fd7ce5SGreg Kroah-Hartman /* 75296fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 75396fd7ce5SGreg Kroah-Hartman */ 75496fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 75596fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 7561c95ba1eSPhilippe Rétornaz 7571c95ba1eSPhilippe Rétornaz return 0; 75896fd7ce5SGreg Kroah-Hartman } 75996fd7ce5SGreg Kroah-Hartman 76096fd7ce5SGreg Kroah-Hartman /** 76196fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 76296fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 76396fd7ce5SGreg Kroah-Hartman * 76496fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 76596fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 76696fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 76796fd7ce5SGreg Kroah-Hartman * 76896fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 76996fd7ce5SGreg Kroah-Hartman * careful to allow for this. 77096fd7ce5SGreg Kroah-Hartman * 77196fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 77296fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 77396fd7ce5SGreg Kroah-Hartman */ 77496fd7ce5SGreg Kroah-Hartman 77596fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 77696fd7ce5SGreg Kroah-Hartman { 77796fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 77896fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 77996fd7ce5SGreg Kroah-Hartman int err = 0; 78096fd7ce5SGreg Kroah-Hartman 78196fd7ce5SGreg Kroah-Hartman /* 78296fd7ce5SGreg Kroah-Hartman * FIXME! What are the locking issues here? This may me overdoing 78396fd7ce5SGreg Kroah-Hartman * things... This question is especially important now that we've 78496fd7ce5SGreg Kroah-Hartman * removed the irqlock. 78596fd7ce5SGreg Kroah-Hartman */ 78696fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 78796fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 78896fd7ce5SGreg Kroah-Hartman /* We may have no line discipline at this point */ 78996fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 79096fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 79196fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 79296fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 79396fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 79496fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 79596fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 79696fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 79796fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 79896fd7ce5SGreg Kroah-Hartman } 79996fd7ce5SGreg Kroah-Hartman /* 80096fd7ce5SGreg Kroah-Hartman * FIXME: Once we trust the LDISC code better we can wait here for 80196fd7ce5SGreg Kroah-Hartman * ldisc completion and fix the driver call race 80296fd7ce5SGreg Kroah-Hartman */ 80396fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 80496fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 80596fd7ce5SGreg Kroah-Hartman /* 80696fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 80796fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 80896fd7ce5SGreg Kroah-Hartman * 80996fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 81096fd7ce5SGreg Kroah-Hartman */ 81196fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 81296fd7ce5SGreg Kroah-Hartman 81396fd7ce5SGreg Kroah-Hartman /* 81496fd7ce5SGreg Kroah-Hartman * this is like tty_ldisc_halt, but we need to give up 815f23eb2b2SLinus Torvalds * the BTM before calling cancel_work_sync, which may 816f23eb2b2SLinus Torvalds * need to wait for another function taking the BTM 81796fd7ce5SGreg Kroah-Hartman */ 81896fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 819f5e3bcc5SAlan Cox tty_unlock(tty); 820f23eb2b2SLinus Torvalds cancel_work_sync(&tty->buf.work); 82196fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 8220c73c08eSJiri Slaby retry: 823f5e3bcc5SAlan Cox tty_lock(tty); 82496fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 82596fd7ce5SGreg Kroah-Hartman 82696fd7ce5SGreg Kroah-Hartman /* At this point we have a closed ldisc and we want to 82796fd7ce5SGreg Kroah-Hartman reopen it. We could defer this to the next open but 82896fd7ce5SGreg Kroah-Hartman it means auditing a lot of other paths so this is 82996fd7ce5SGreg Kroah-Hartman a FIXME */ 83096fd7ce5SGreg Kroah-Hartman if (tty->ldisc) { /* Not yet closed */ 8310c73c08eSJiri Slaby if (atomic_read(&tty->ldisc->users) != 1) { 8320c73c08eSJiri Slaby char cur_n[TASK_COMM_LEN], tty_n[64]; 8330c73c08eSJiri Slaby long timeout = 3 * HZ; 834f5e3bcc5SAlan Cox tty_unlock(tty); 8350c73c08eSJiri Slaby 8360c73c08eSJiri Slaby while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { 8370c73c08eSJiri Slaby timeout = MAX_SCHEDULE_TIMEOUT; 8380c73c08eSJiri Slaby printk_ratelimited(KERN_WARNING 8390c73c08eSJiri Slaby "%s: waiting (%s) for %s took too long, but we keep waiting...\n", 8400c73c08eSJiri Slaby __func__, get_task_comm(cur_n, current), 8410c73c08eSJiri Slaby tty_name(tty, tty_n)); 8420c73c08eSJiri Slaby } 8430c73c08eSJiri Slaby mutex_unlock(&tty->ldisc_mutex); 8440c73c08eSJiri Slaby goto retry; 8450c73c08eSJiri Slaby } 84630042072SJiri Slaby 84796fd7ce5SGreg Kroah-Hartman if (reset == 0) { 8481c95ba1eSPhilippe Rétornaz 8491c95ba1eSPhilippe Rétornaz if (!tty_ldisc_reinit(tty, tty->termios->c_line)) 85096fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 8511c95ba1eSPhilippe Rétornaz else 8521c95ba1eSPhilippe Rétornaz err = 1; 85396fd7ce5SGreg Kroah-Hartman } 85496fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 85596fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 85696fd7ce5SGreg Kroah-Hartman if (reset || err) { 8571c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 85896fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 85996fd7ce5SGreg Kroah-Hartman } 86096fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 86196fd7ce5SGreg Kroah-Hartman } 86296fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 86396fd7ce5SGreg Kroah-Hartman if (reset) 86496fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 86596fd7ce5SGreg Kroah-Hartman } 86696fd7ce5SGreg Kroah-Hartman 86796fd7ce5SGreg Kroah-Hartman /** 86896fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 86996fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 87096fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 87196fd7ce5SGreg Kroah-Hartman * 87296fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 87396fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 87496fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 87596fd7ce5SGreg Kroah-Hartman */ 87696fd7ce5SGreg Kroah-Hartman 87796fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 87896fd7ce5SGreg Kroah-Hartman { 87996fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 88096fd7ce5SGreg Kroah-Hartman int retval; 88196fd7ce5SGreg Kroah-Hartman 88296fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 88396fd7ce5SGreg Kroah-Hartman if (retval) 88496fd7ce5SGreg Kroah-Hartman return retval; 88596fd7ce5SGreg Kroah-Hartman 88696fd7ce5SGreg Kroah-Hartman if (o_tty) { 88796fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 88896fd7ce5SGreg Kroah-Hartman if (retval) { 88996fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 89096fd7ce5SGreg Kroah-Hartman return retval; 89196fd7ce5SGreg Kroah-Hartman } 89296fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 89396fd7ce5SGreg Kroah-Hartman } 89496fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 89596fd7ce5SGreg Kroah-Hartman return 0; 89696fd7ce5SGreg Kroah-Hartman } 897f5e3bcc5SAlan Cox 898f5e3bcc5SAlan Cox static void tty_ldisc_kill(struct tty_struct *tty) 899f5e3bcc5SAlan Cox { 900f5e3bcc5SAlan Cox mutex_lock(&tty->ldisc_mutex); 901f5e3bcc5SAlan Cox /* 902f5e3bcc5SAlan Cox * Now kill off the ldisc 903f5e3bcc5SAlan Cox */ 904f5e3bcc5SAlan Cox tty_ldisc_close(tty, tty->ldisc); 905f5e3bcc5SAlan Cox tty_ldisc_put(tty->ldisc); 906f5e3bcc5SAlan Cox /* Force an oops if we mess this up */ 907f5e3bcc5SAlan Cox tty->ldisc = NULL; 908f5e3bcc5SAlan Cox 909f5e3bcc5SAlan Cox /* Ensure the next open requests the N_TTY ldisc */ 910f5e3bcc5SAlan Cox tty_set_termios_ldisc(tty, N_TTY); 911f5e3bcc5SAlan Cox mutex_unlock(&tty->ldisc_mutex); 912f5e3bcc5SAlan Cox } 913f5e3bcc5SAlan Cox 91496fd7ce5SGreg Kroah-Hartman /** 91596fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 91696fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 91796fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 91896fd7ce5SGreg Kroah-Hartman * 91996fd7ce5SGreg Kroah-Hartman * Called during the final close of a tty/pty pair in order to shut down 92096fd7ce5SGreg Kroah-Hartman * the line discpline layer. On exit the ldisc assigned is N_TTY and the 92196fd7ce5SGreg Kroah-Hartman * ldisc has not been opened. 92296fd7ce5SGreg Kroah-Hartman */ 92396fd7ce5SGreg Kroah-Hartman 92496fd7ce5SGreg Kroah-Hartman void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) 92596fd7ce5SGreg Kroah-Hartman { 92696fd7ce5SGreg Kroah-Hartman /* 92796fd7ce5SGreg Kroah-Hartman * Prevent flush_to_ldisc() from rescheduling the work for later. Then 92896fd7ce5SGreg Kroah-Hartman * kill any delayed work. As this is the final close it does not 92996fd7ce5SGreg Kroah-Hartman * race with the set_ldisc code path. 93096fd7ce5SGreg Kroah-Hartman */ 93196fd7ce5SGreg Kroah-Hartman 932f5e3bcc5SAlan Cox tty_unlock_pair(tty, o_tty); 93396fd7ce5SGreg Kroah-Hartman tty_ldisc_halt(tty); 9340a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 935f5e3bcc5SAlan Cox if (o_tty) { 936f5e3bcc5SAlan Cox tty_ldisc_halt(o_tty); 937f5e3bcc5SAlan Cox tty_ldisc_flush_works(o_tty); 938f5e3bcc5SAlan Cox } 939f5e3bcc5SAlan Cox tty_lock_pair(tty, o_tty); 94096fd7ce5SGreg Kroah-Hartman 94196fd7ce5SGreg Kroah-Hartman 942f5e3bcc5SAlan Cox tty_ldisc_kill(tty); 94396fd7ce5SGreg Kroah-Hartman if (o_tty) 944f5e3bcc5SAlan Cox tty_ldisc_kill(o_tty); 94596fd7ce5SGreg Kroah-Hartman 94696fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 94796fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 94896fd7ce5SGreg Kroah-Hartman } 94996fd7ce5SGreg Kroah-Hartman 95096fd7ce5SGreg Kroah-Hartman /** 95196fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 95296fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 95396fd7ce5SGreg Kroah-Hartman * 95496fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 95596fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 95696fd7ce5SGreg Kroah-Hartman */ 95796fd7ce5SGreg Kroah-Hartman 95896fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 95996fd7ce5SGreg Kroah-Hartman { 96096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_get(N_TTY); 96196fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 96296fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 96396fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 96496fd7ce5SGreg Kroah-Hartman } 96596fd7ce5SGreg Kroah-Hartman 9666716671dSJiri Slaby /** 9676716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 9686716671dSJiri Slaby * @tty: tty that was allocated recently 9696716671dSJiri Slaby * 9706716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 9716716671dSJiri Slaby * this call is made. 9726716671dSJiri Slaby */ 9736716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 9746716671dSJiri Slaby { 9756716671dSJiri Slaby put_ldisc(tty->ldisc); 9766716671dSJiri Slaby tty_ldisc_assign(tty, NULL); 9776716671dSJiri Slaby } 9786716671dSJiri Slaby 97996fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 98096fd7ce5SGreg Kroah-Hartman { 98196fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 98296fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 98396fd7ce5SGreg Kroah-Hartman } 984