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> 390c73c08eSJiri Slaby #include <linux/ratelimit.h> 4096fd7ce5SGreg Kroah-Hartman 4196fd7ce5SGreg Kroah-Hartman /* 4296fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 4396fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4496fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4596fd7ce5SGreg Kroah-Hartman */ 4696fd7ce5SGreg Kroah-Hartman 4796fd7ce5SGreg Kroah-Hartman static DEFINE_SPINLOCK(tty_ldisc_lock); 4896fd7ce5SGreg Kroah-Hartman static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); 49100eeae2SJiri Slaby static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle); 5096fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 5196fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 5296fd7ce5SGreg Kroah-Hartman 5396fd7ce5SGreg Kroah-Hartman static inline struct tty_ldisc *get_ldisc(struct tty_ldisc *ld) 5496fd7ce5SGreg Kroah-Hartman { 5596fd7ce5SGreg Kroah-Hartman if (ld) 5696fd7ce5SGreg Kroah-Hartman atomic_inc(&ld->users); 5796fd7ce5SGreg Kroah-Hartman return ld; 5896fd7ce5SGreg Kroah-Hartman } 5996fd7ce5SGreg Kroah-Hartman 6096fd7ce5SGreg Kroah-Hartman static void put_ldisc(struct tty_ldisc *ld) 6196fd7ce5SGreg Kroah-Hartman { 6296fd7ce5SGreg Kroah-Hartman unsigned long flags; 6396fd7ce5SGreg Kroah-Hartman 6496fd7ce5SGreg Kroah-Hartman if (WARN_ON_ONCE(!ld)) 6596fd7ce5SGreg Kroah-Hartman return; 6696fd7ce5SGreg Kroah-Hartman 6796fd7ce5SGreg Kroah-Hartman /* 6896fd7ce5SGreg Kroah-Hartman * If this is the last user, free the ldisc, and 6996fd7ce5SGreg Kroah-Hartman * release the ldisc ops. 7096fd7ce5SGreg Kroah-Hartman * 7196fd7ce5SGreg Kroah-Hartman * We really want an "atomic_dec_and_lock_irqsave()", 7296fd7ce5SGreg Kroah-Hartman * but we don't have it, so this does it by hand. 7396fd7ce5SGreg Kroah-Hartman */ 7496fd7ce5SGreg Kroah-Hartman local_irq_save(flags); 7596fd7ce5SGreg Kroah-Hartman if (atomic_dec_and_lock(&ld->users, &tty_ldisc_lock)) { 7696fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldo = ld->ops; 7796fd7ce5SGreg Kroah-Hartman 7896fd7ce5SGreg Kroah-Hartman ldo->refcount--; 7996fd7ce5SGreg Kroah-Hartman module_put(ldo->owner); 8096fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 8196fd7ce5SGreg Kroah-Hartman 8296fd7ce5SGreg Kroah-Hartman kfree(ld); 8396fd7ce5SGreg Kroah-Hartman return; 8496fd7ce5SGreg Kroah-Hartman } 8596fd7ce5SGreg Kroah-Hartman local_irq_restore(flags); 86100eeae2SJiri Slaby wake_up(&tty_ldisc_idle); 8796fd7ce5SGreg Kroah-Hartman } 8896fd7ce5SGreg Kroah-Hartman 8996fd7ce5SGreg Kroah-Hartman /** 9096fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 9196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 9296fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 9396fd7ce5SGreg Kroah-Hartman * 9496fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 9596fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 9696fd7ce5SGreg Kroah-Hartman * from this point onwards. 9796fd7ce5SGreg Kroah-Hartman * 9896fd7ce5SGreg Kroah-Hartman * Locking: 9996fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 10096fd7ce5SGreg Kroah-Hartman */ 10196fd7ce5SGreg Kroah-Hartman 10296fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 10396fd7ce5SGreg Kroah-Hartman { 10496fd7ce5SGreg Kroah-Hartman unsigned long flags; 10596fd7ce5SGreg Kroah-Hartman int ret = 0; 10696fd7ce5SGreg Kroah-Hartman 10796fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 10896fd7ce5SGreg Kroah-Hartman return -EINVAL; 10996fd7ce5SGreg Kroah-Hartman 11096fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 11196fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 11296fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 11396fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 11496fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 11596fd7ce5SGreg Kroah-Hartman 11696fd7ce5SGreg Kroah-Hartman return ret; 11796fd7ce5SGreg Kroah-Hartman } 11896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 11996fd7ce5SGreg Kroah-Hartman 12096fd7ce5SGreg Kroah-Hartman /** 12196fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 12296fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 12396fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 12496fd7ce5SGreg Kroah-Hartman * 12596fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 12696fd7ce5SGreg Kroah-Hartman * currently in use. 12796fd7ce5SGreg Kroah-Hartman * 12896fd7ce5SGreg Kroah-Hartman * Locking: 12996fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 13096fd7ce5SGreg Kroah-Hartman */ 13196fd7ce5SGreg Kroah-Hartman 13296fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 13396fd7ce5SGreg Kroah-Hartman { 13496fd7ce5SGreg Kroah-Hartman unsigned long flags; 13596fd7ce5SGreg Kroah-Hartman int ret = 0; 13696fd7ce5SGreg Kroah-Hartman 13796fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 13896fd7ce5SGreg Kroah-Hartman return -EINVAL; 13996fd7ce5SGreg Kroah-Hartman 14096fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 14196fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 14296fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 14396fd7ce5SGreg Kroah-Hartman else 14496fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 14596fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 14696fd7ce5SGreg Kroah-Hartman 14796fd7ce5SGreg Kroah-Hartman return ret; 14896fd7ce5SGreg Kroah-Hartman } 14996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 15096fd7ce5SGreg Kroah-Hartman 15196fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 15296fd7ce5SGreg Kroah-Hartman { 15396fd7ce5SGreg Kroah-Hartman unsigned long flags; 15496fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 15596fd7ce5SGreg Kroah-Hartman 15696fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 15796fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 15896fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 15996fd7ce5SGreg Kroah-Hartman if (ldops) { 16096fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 16196fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 16296fd7ce5SGreg Kroah-Hartman ldops->refcount++; 16396fd7ce5SGreg Kroah-Hartman ret = ldops; 16496fd7ce5SGreg Kroah-Hartman } 16596fd7ce5SGreg Kroah-Hartman } 16696fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 16796fd7ce5SGreg Kroah-Hartman return ret; 16896fd7ce5SGreg Kroah-Hartman } 16996fd7ce5SGreg Kroah-Hartman 17096fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 17196fd7ce5SGreg Kroah-Hartman { 17296fd7ce5SGreg Kroah-Hartman unsigned long flags; 17396fd7ce5SGreg Kroah-Hartman 17496fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 17596fd7ce5SGreg Kroah-Hartman ldops->refcount--; 17696fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 17796fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 17896fd7ce5SGreg Kroah-Hartman } 17996fd7ce5SGreg Kroah-Hartman 18096fd7ce5SGreg Kroah-Hartman /** 18196fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 18296fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 18396fd7ce5SGreg Kroah-Hartman * 18496fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 18596fd7ce5SGreg Kroah-Hartman * module locking counts. Returns NULL if the discipline is not available. 18696fd7ce5SGreg Kroah-Hartman * Returns a pointer to the discipline and bumps the ref count if it is 18796fd7ce5SGreg Kroah-Hartman * available 18896fd7ce5SGreg Kroah-Hartman * 18996fd7ce5SGreg Kroah-Hartman * Locking: 19096fd7ce5SGreg Kroah-Hartman * takes tty_ldisc_lock to guard against ldisc races 19196fd7ce5SGreg Kroah-Hartman */ 19296fd7ce5SGreg Kroah-Hartman 19396fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_get(int disc) 19496fd7ce5SGreg Kroah-Hartman { 19596fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 19696fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 19796fd7ce5SGreg Kroah-Hartman 19896fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 19996fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 20096fd7ce5SGreg Kroah-Hartman 20196fd7ce5SGreg Kroah-Hartman /* 20296fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 20396fd7ce5SGreg Kroah-Hartman * dynamically and try again. 20496fd7ce5SGreg Kroah-Hartman */ 20596fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 20696fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 20796fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 20896fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 20996fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 21096fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 21196fd7ce5SGreg Kroah-Hartman } 21296fd7ce5SGreg Kroah-Hartman 21396fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 21496fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 21596fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 21696fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 21796fd7ce5SGreg Kroah-Hartman } 21896fd7ce5SGreg Kroah-Hartman 21996fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 22096fd7ce5SGreg Kroah-Hartman atomic_set(&ld->users, 1); 22196fd7ce5SGreg Kroah-Hartman return ld; 22296fd7ce5SGreg Kroah-Hartman } 22396fd7ce5SGreg Kroah-Hartman 22496fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 22596fd7ce5SGreg Kroah-Hartman { 22696fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 22796fd7ce5SGreg Kroah-Hartman } 22896fd7ce5SGreg Kroah-Hartman 22996fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 23096fd7ce5SGreg Kroah-Hartman { 23196fd7ce5SGreg Kroah-Hartman (*pos)++; 23296fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 23396fd7ce5SGreg Kroah-Hartman } 23496fd7ce5SGreg Kroah-Hartman 23596fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 23696fd7ce5SGreg Kroah-Hartman { 23796fd7ce5SGreg Kroah-Hartman } 23896fd7ce5SGreg Kroah-Hartman 23996fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 24096fd7ce5SGreg Kroah-Hartman { 24196fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 24296fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 24396fd7ce5SGreg Kroah-Hartman 24496fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 24596fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 24696fd7ce5SGreg Kroah-Hartman return 0; 24796fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 24896fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 24996fd7ce5SGreg Kroah-Hartman return 0; 25096fd7ce5SGreg Kroah-Hartman } 25196fd7ce5SGreg Kroah-Hartman 25296fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 25396fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 25496fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 25596fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 25696fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 25796fd7ce5SGreg Kroah-Hartman }; 25896fd7ce5SGreg Kroah-Hartman 25996fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 26096fd7ce5SGreg Kroah-Hartman { 26196fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 26296fd7ce5SGreg Kroah-Hartman } 26396fd7ce5SGreg Kroah-Hartman 26496fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 26596fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 26696fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 26796fd7ce5SGreg Kroah-Hartman .read = seq_read, 26896fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 26996fd7ce5SGreg Kroah-Hartman .release = seq_release, 27096fd7ce5SGreg Kroah-Hartman }; 27196fd7ce5SGreg Kroah-Hartman 27296fd7ce5SGreg Kroah-Hartman /** 27396fd7ce5SGreg Kroah-Hartman * tty_ldisc_assign - set ldisc on a tty 27496fd7ce5SGreg Kroah-Hartman * @tty: tty to assign 27596fd7ce5SGreg Kroah-Hartman * @ld: line discipline 27696fd7ce5SGreg Kroah-Hartman * 27796fd7ce5SGreg Kroah-Hartman * Install an instance of a line discipline into a tty structure. The 27896fd7ce5SGreg Kroah-Hartman * ldisc must have a reference count above zero to ensure it remains. 27996fd7ce5SGreg Kroah-Hartman * The tty instance refcount starts at zero. 28096fd7ce5SGreg Kroah-Hartman * 28196fd7ce5SGreg Kroah-Hartman * Locking: 28296fd7ce5SGreg Kroah-Hartman * Caller must hold references 28396fd7ce5SGreg Kroah-Hartman */ 28496fd7ce5SGreg Kroah-Hartman 28596fd7ce5SGreg Kroah-Hartman static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) 28696fd7ce5SGreg Kroah-Hartman { 28796fd7ce5SGreg Kroah-Hartman tty->ldisc = ld; 28896fd7ce5SGreg Kroah-Hartman } 28996fd7ce5SGreg Kroah-Hartman 29096fd7ce5SGreg Kroah-Hartman /** 29196fd7ce5SGreg Kroah-Hartman * tty_ldisc_try - internal helper 29296fd7ce5SGreg Kroah-Hartman * @tty: the tty 29396fd7ce5SGreg Kroah-Hartman * 29496fd7ce5SGreg Kroah-Hartman * Make a single attempt to grab and bump the refcount on 29596fd7ce5SGreg Kroah-Hartman * the tty ldisc. Return 0 on failure or 1 on success. This is 29696fd7ce5SGreg Kroah-Hartman * used to implement both the waiting and non waiting versions 29796fd7ce5SGreg Kroah-Hartman * of tty_ldisc_ref 29896fd7ce5SGreg Kroah-Hartman * 29996fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 30096fd7ce5SGreg Kroah-Hartman */ 30196fd7ce5SGreg Kroah-Hartman 30296fd7ce5SGreg Kroah-Hartman static struct tty_ldisc *tty_ldisc_try(struct tty_struct *tty) 30396fd7ce5SGreg Kroah-Hartman { 30496fd7ce5SGreg Kroah-Hartman unsigned long flags; 30596fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 30696fd7ce5SGreg Kroah-Hartman 30796fd7ce5SGreg Kroah-Hartman spin_lock_irqsave(&tty_ldisc_lock, flags); 30896fd7ce5SGreg Kroah-Hartman ld = NULL; 30996fd7ce5SGreg Kroah-Hartman if (test_bit(TTY_LDISC, &tty->flags)) 31096fd7ce5SGreg Kroah-Hartman ld = get_ldisc(tty->ldisc); 31196fd7ce5SGreg Kroah-Hartman spin_unlock_irqrestore(&tty_ldisc_lock, flags); 31296fd7ce5SGreg Kroah-Hartman return ld; 31396fd7ce5SGreg Kroah-Hartman } 31496fd7ce5SGreg Kroah-Hartman 31596fd7ce5SGreg Kroah-Hartman /** 31696fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 31796fd7ce5SGreg Kroah-Hartman * @tty: tty device 31896fd7ce5SGreg Kroah-Hartman * 31996fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 32096fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 32196fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 32296fd7ce5SGreg Kroah-Hartman * 32396fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 32496fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 32596fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 32696fd7ce5SGreg Kroah-Hartman * (which we check for) 32796fd7ce5SGreg Kroah-Hartman * 32896fd7ce5SGreg Kroah-Hartman * Locking: call functions take tty_ldisc_lock 32996fd7ce5SGreg Kroah-Hartman */ 33096fd7ce5SGreg Kroah-Hartman 33196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 33296fd7ce5SGreg Kroah-Hartman { 33396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 33496fd7ce5SGreg Kroah-Hartman 33596fd7ce5SGreg Kroah-Hartman /* wait_event is a macro */ 33696fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, (ld = tty_ldisc_try(tty)) != NULL); 33796fd7ce5SGreg Kroah-Hartman return ld; 33896fd7ce5SGreg Kroah-Hartman } 33996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 34096fd7ce5SGreg Kroah-Hartman 34196fd7ce5SGreg Kroah-Hartman /** 34296fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 34396fd7ce5SGreg Kroah-Hartman * @tty: tty device 34496fd7ce5SGreg Kroah-Hartman * 34596fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 34696fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 34796fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 34896fd7ce5SGreg Kroah-Hartman * 34996fd7ce5SGreg Kroah-Hartman * Locking: called functions take tty_ldisc_lock 35096fd7ce5SGreg Kroah-Hartman */ 35196fd7ce5SGreg Kroah-Hartman 35296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 35396fd7ce5SGreg Kroah-Hartman { 35496fd7ce5SGreg Kroah-Hartman return tty_ldisc_try(tty); 35596fd7ce5SGreg Kroah-Hartman } 35696fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 35796fd7ce5SGreg Kroah-Hartman 35896fd7ce5SGreg Kroah-Hartman /** 35996fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 36096fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 36196fd7ce5SGreg Kroah-Hartman * 36296fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 36396fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 36496fd7ce5SGreg Kroah-Hartman * 36596fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock 36696fd7ce5SGreg Kroah-Hartman */ 36796fd7ce5SGreg Kroah-Hartman 36896fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 36996fd7ce5SGreg Kroah-Hartman { 37096fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 37196fd7ce5SGreg Kroah-Hartman } 37296fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 37396fd7ce5SGreg Kroah-Hartman 37496fd7ce5SGreg Kroah-Hartman static inline void tty_ldisc_put(struct tty_ldisc *ld) 37596fd7ce5SGreg Kroah-Hartman { 37696fd7ce5SGreg Kroah-Hartman put_ldisc(ld); 37796fd7ce5SGreg Kroah-Hartman } 37896fd7ce5SGreg Kroah-Hartman 37996fd7ce5SGreg Kroah-Hartman /** 38096fd7ce5SGreg Kroah-Hartman * tty_ldisc_enable - allow ldisc use 38196fd7ce5SGreg Kroah-Hartman * @tty: terminal to activate ldisc on 38296fd7ce5SGreg Kroah-Hartman * 38396fd7ce5SGreg Kroah-Hartman * Set the TTY_LDISC flag when the line discipline can be called 38496fd7ce5SGreg Kroah-Hartman * again. Do necessary wakeups for existing sleepers. Clear the LDISC 38596fd7ce5SGreg Kroah-Hartman * changing flag to indicate any ldisc change is now over. 38696fd7ce5SGreg Kroah-Hartman * 38796fd7ce5SGreg Kroah-Hartman * Note: nobody should set the TTY_LDISC bit except via this function. 38896fd7ce5SGreg Kroah-Hartman * Clearing directly is allowed. 38996fd7ce5SGreg Kroah-Hartman */ 39096fd7ce5SGreg Kroah-Hartman 39196fd7ce5SGreg Kroah-Hartman void tty_ldisc_enable(struct tty_struct *tty) 39296fd7ce5SGreg Kroah-Hartman { 39396fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC, &tty->flags); 39496fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 39596fd7ce5SGreg Kroah-Hartman wake_up(&tty_ldisc_wait); 39696fd7ce5SGreg Kroah-Hartman } 39796fd7ce5SGreg Kroah-Hartman 39896fd7ce5SGreg Kroah-Hartman /** 39996fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 40096fd7ce5SGreg Kroah-Hartman * @tty: tty 40196fd7ce5SGreg Kroah-Hartman * 40296fd7ce5SGreg Kroah-Hartman * Flush the line discipline queue (if any) for this tty. If there 40396fd7ce5SGreg Kroah-Hartman * is no line discipline active this is a no-op. 40496fd7ce5SGreg Kroah-Hartman */ 40596fd7ce5SGreg Kroah-Hartman 40696fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 40796fd7ce5SGreg Kroah-Hartman { 40896fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 40996fd7ce5SGreg Kroah-Hartman if (ld) { 41096fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 41196fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 41296fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 41396fd7ce5SGreg Kroah-Hartman } 41496fd7ce5SGreg Kroah-Hartman tty_buffer_flush(tty); 41596fd7ce5SGreg Kroah-Hartman } 41696fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 41796fd7ce5SGreg Kroah-Hartman 41896fd7ce5SGreg Kroah-Hartman /** 41996fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 42096fd7ce5SGreg Kroah-Hartman * @tty: tty structure 42196fd7ce5SGreg Kroah-Hartman * @num: line discipline number 42296fd7ce5SGreg Kroah-Hartman * 42396fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 42496fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 42596fd7ce5SGreg Kroah-Hartman * any harm. 42696fd7ce5SGreg Kroah-Hartman * 42796fd7ce5SGreg Kroah-Hartman * Locking: takes termios_mutex 42896fd7ce5SGreg Kroah-Hartman */ 42996fd7ce5SGreg Kroah-Hartman 43096fd7ce5SGreg Kroah-Hartman static void tty_set_termios_ldisc(struct tty_struct *tty, int num) 43196fd7ce5SGreg Kroah-Hartman { 43296fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 43396fd7ce5SGreg Kroah-Hartman tty->termios->c_line = num; 43496fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 43596fd7ce5SGreg Kroah-Hartman } 43696fd7ce5SGreg Kroah-Hartman 43796fd7ce5SGreg Kroah-Hartman /** 43896fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 43996fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 44096fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 44196fd7ce5SGreg Kroah-Hartman * 44296fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 44396fd7ce5SGreg Kroah-Hartman * point. 44496fd7ce5SGreg Kroah-Hartman * 44596fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 44696fd7ce5SGreg Kroah-Hartman */ 44796fd7ce5SGreg Kroah-Hartman 44896fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 44996fd7ce5SGreg Kroah-Hartman { 45096fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 45196fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 45296fd7ce5SGreg Kroah-Hartman int ret; 45396fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 45496fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4557f90cfc5SJiri Slaby if (ret) 4567f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 45796fd7ce5SGreg Kroah-Hartman return ret; 45896fd7ce5SGreg Kroah-Hartman } 45996fd7ce5SGreg Kroah-Hartman return 0; 46096fd7ce5SGreg Kroah-Hartman } 46196fd7ce5SGreg Kroah-Hartman 46296fd7ce5SGreg Kroah-Hartman /** 46396fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 46496fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 46596fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 46696fd7ce5SGreg Kroah-Hartman * 46796fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 46896fd7ce5SGreg Kroah-Hartman * point. 46996fd7ce5SGreg Kroah-Hartman */ 47096fd7ce5SGreg Kroah-Hartman 47196fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 47296fd7ce5SGreg Kroah-Hartman { 47396fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 47496fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 47596fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 47696fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 47796fd7ce5SGreg Kroah-Hartman } 47896fd7ce5SGreg Kroah-Hartman 47996fd7ce5SGreg Kroah-Hartman /** 48096fd7ce5SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 48196fd7ce5SGreg Kroah-Hartman * @tty: tty to recover 48296fd7ce5SGreg Kroah-Hartman * @old: previous ldisc 48396fd7ce5SGreg Kroah-Hartman * 48496fd7ce5SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 48596fd7ce5SGreg Kroah-Hartman * change fails due to an open error 48696fd7ce5SGreg Kroah-Hartman */ 48796fd7ce5SGreg Kroah-Hartman 48896fd7ce5SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 48996fd7ce5SGreg Kroah-Hartman { 49096fd7ce5SGreg Kroah-Hartman char buf[64]; 49196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *new_ldisc; 49296fd7ce5SGreg Kroah-Hartman int r; 49396fd7ce5SGreg Kroah-Hartman 49496fd7ce5SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 49596fd7ce5SGreg Kroah-Hartman old = tty_ldisc_get(old->ops->num); 49696fd7ce5SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 49796fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, old); 49896fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 49996fd7ce5SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 50096fd7ce5SGreg Kroah-Hartman tty_ldisc_put(old); 50196fd7ce5SGreg Kroah-Hartman /* This driver is always present */ 50296fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(N_TTY); 50396fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 50496fd7ce5SGreg Kroah-Hartman panic("n_tty: get"); 50596fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 50696fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 50796fd7ce5SGreg Kroah-Hartman r = tty_ldisc_open(tty, new_ldisc); 50896fd7ce5SGreg Kroah-Hartman if (r < 0) 50996fd7ce5SGreg Kroah-Hartman panic("Couldn't open N_TTY ldisc for " 51096fd7ce5SGreg Kroah-Hartman "%s --- error %d.", 51196fd7ce5SGreg Kroah-Hartman tty_name(tty, buf), r); 51296fd7ce5SGreg Kroah-Hartman } 51396fd7ce5SGreg Kroah-Hartman } 51496fd7ce5SGreg Kroah-Hartman 51596fd7ce5SGreg Kroah-Hartman /** 51696fd7ce5SGreg Kroah-Hartman * tty_ldisc_halt - shut down the line discipline 51796fd7ce5SGreg Kroah-Hartman * @tty: tty device 51896fd7ce5SGreg Kroah-Hartman * 51996fd7ce5SGreg Kroah-Hartman * Shut down the line discipline and work queue for this tty device. 52096fd7ce5SGreg Kroah-Hartman * The TTY_LDISC flag being cleared ensures no further references can 52196fd7ce5SGreg Kroah-Hartman * be obtained while the delayed work queue halt ensures that no more 52296fd7ce5SGreg Kroah-Hartman * data is fed to the ldisc. 52396fd7ce5SGreg Kroah-Hartman * 52496fd7ce5SGreg Kroah-Hartman * You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex) 52596fd7ce5SGreg Kroah-Hartman * in order to make sure any currently executing ldisc work is also 52696fd7ce5SGreg Kroah-Hartman * flushed. 52796fd7ce5SGreg Kroah-Hartman */ 52896fd7ce5SGreg Kroah-Hartman 52996fd7ce5SGreg Kroah-Hartman static int tty_ldisc_halt(struct tty_struct *tty) 53096fd7ce5SGreg Kroah-Hartman { 53196fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 532f23eb2b2SLinus Torvalds return cancel_work_sync(&tty->buf.work); 53396fd7ce5SGreg Kroah-Hartman } 53496fd7ce5SGreg Kroah-Hartman 53596fd7ce5SGreg Kroah-Hartman /** 5360a1f1a0bSTejun Heo * tty_ldisc_flush_works - flush all works of a tty 5370a1f1a0bSTejun Heo * @tty: tty device to flush works for 5380a1f1a0bSTejun Heo * 5390a1f1a0bSTejun Heo * Sync flush all works belonging to @tty. 5400a1f1a0bSTejun Heo */ 5410a1f1a0bSTejun Heo static void tty_ldisc_flush_works(struct tty_struct *tty) 5420a1f1a0bSTejun Heo { 5430a1f1a0bSTejun Heo flush_work_sync(&tty->hangup_work); 5440a1f1a0bSTejun Heo flush_work_sync(&tty->SAK_work); 545f23eb2b2SLinus Torvalds flush_work_sync(&tty->buf.work); 5460a1f1a0bSTejun Heo } 5470a1f1a0bSTejun Heo 5480a1f1a0bSTejun Heo /** 549100eeae2SJiri Slaby * tty_ldisc_wait_idle - wait for the ldisc to become idle 550100eeae2SJiri Slaby * @tty: tty to wait for 551df92d056SJiri Slaby * @timeout: for how long to wait at most 552100eeae2SJiri Slaby * 553100eeae2SJiri Slaby * Wait for the line discipline to become idle. The discipline must 554100eeae2SJiri Slaby * have been halted for this to guarantee it remains idle. 555100eeae2SJiri Slaby */ 556df92d056SJiri Slaby static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) 557100eeae2SJiri Slaby { 558df92d056SJiri Slaby long ret; 55992f6fa09SJiri Slaby ret = wait_event_timeout(tty_ldisc_idle, 560df92d056SJiri Slaby atomic_read(&tty->ldisc->users) == 1, timeout); 561100eeae2SJiri Slaby if (ret < 0) 562100eeae2SJiri Slaby return ret; 563100eeae2SJiri Slaby return ret > 0 ? 0 : -EBUSY; 564100eeae2SJiri Slaby } 565100eeae2SJiri Slaby 566100eeae2SJiri Slaby /** 56796fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 56896fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 56996fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 57096fd7ce5SGreg Kroah-Hartman * 57196fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 57296fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 57396fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 57496fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 57596fd7ce5SGreg Kroah-Hartman * 57696fd7ce5SGreg Kroah-Hartman * Locking: takes tty_ldisc_lock, termios_mutex 57796fd7ce5SGreg Kroah-Hartman */ 57896fd7ce5SGreg Kroah-Hartman 57996fd7ce5SGreg Kroah-Hartman int tty_set_ldisc(struct tty_struct *tty, int ldisc) 58096fd7ce5SGreg Kroah-Hartman { 58196fd7ce5SGreg Kroah-Hartman int retval; 58296fd7ce5SGreg Kroah-Hartman struct tty_ldisc *o_ldisc, *new_ldisc; 58396fd7ce5SGreg Kroah-Hartman int work, o_work = 0; 58496fd7ce5SGreg Kroah-Hartman struct tty_struct *o_tty; 58596fd7ce5SGreg Kroah-Hartman 58696fd7ce5SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(ldisc); 58796fd7ce5SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 58896fd7ce5SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 58996fd7ce5SGreg Kroah-Hartman 59096fd7ce5SGreg Kroah-Hartman tty_lock(); 59196fd7ce5SGreg Kroah-Hartman /* 59296fd7ce5SGreg Kroah-Hartman * We need to look at the tty locking here for pty/tty pairs 59396fd7ce5SGreg Kroah-Hartman * when both sides try to change in parallel. 59496fd7ce5SGreg Kroah-Hartman */ 59596fd7ce5SGreg Kroah-Hartman 59696fd7ce5SGreg Kroah-Hartman o_tty = tty->link; /* o_tty is the pty side or NULL */ 59796fd7ce5SGreg Kroah-Hartman 59896fd7ce5SGreg Kroah-Hartman 59996fd7ce5SGreg Kroah-Hartman /* 60096fd7ce5SGreg Kroah-Hartman * Check the no-op case 60196fd7ce5SGreg Kroah-Hartman */ 60296fd7ce5SGreg Kroah-Hartman 60396fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num == ldisc) { 60496fd7ce5SGreg Kroah-Hartman tty_unlock(); 60596fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 60696fd7ce5SGreg Kroah-Hartman return 0; 60796fd7ce5SGreg Kroah-Hartman } 60896fd7ce5SGreg Kroah-Hartman 60996fd7ce5SGreg Kroah-Hartman tty_unlock(); 61096fd7ce5SGreg Kroah-Hartman /* 61196fd7ce5SGreg Kroah-Hartman * Problem: What do we do if this blocks ? 61296fd7ce5SGreg Kroah-Hartman * We could deadlock here 61396fd7ce5SGreg Kroah-Hartman */ 61496fd7ce5SGreg Kroah-Hartman 61596fd7ce5SGreg Kroah-Hartman tty_wait_until_sent(tty, 0); 61696fd7ce5SGreg Kroah-Hartman 61796fd7ce5SGreg Kroah-Hartman tty_lock(); 61896fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 61996fd7ce5SGreg Kroah-Hartman 62096fd7ce5SGreg Kroah-Hartman /* 62196fd7ce5SGreg Kroah-Hartman * We could be midstream of another ldisc change which has 62296fd7ce5SGreg Kroah-Hartman * dropped the lock during processing. If so we need to wait. 62396fd7ce5SGreg Kroah-Hartman */ 62496fd7ce5SGreg Kroah-Hartman 62596fd7ce5SGreg Kroah-Hartman while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { 62696fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 62796fd7ce5SGreg Kroah-Hartman tty_unlock(); 62896fd7ce5SGreg Kroah-Hartman wait_event(tty_ldisc_wait, 62996fd7ce5SGreg Kroah-Hartman test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); 63096fd7ce5SGreg Kroah-Hartman tty_lock(); 63196fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 63296fd7ce5SGreg Kroah-Hartman } 63396fd7ce5SGreg Kroah-Hartman 63496fd7ce5SGreg Kroah-Hartman set_bit(TTY_LDISC_CHANGING, &tty->flags); 63596fd7ce5SGreg Kroah-Hartman 63696fd7ce5SGreg Kroah-Hartman /* 63796fd7ce5SGreg Kroah-Hartman * No more input please, we are switching. The new ldisc 63896fd7ce5SGreg Kroah-Hartman * will update this value in the ldisc open function 63996fd7ce5SGreg Kroah-Hartman */ 64096fd7ce5SGreg Kroah-Hartman 64196fd7ce5SGreg Kroah-Hartman tty->receive_room = 0; 64296fd7ce5SGreg Kroah-Hartman 64396fd7ce5SGreg Kroah-Hartman o_ldisc = tty->ldisc; 64496fd7ce5SGreg Kroah-Hartman 64596fd7ce5SGreg Kroah-Hartman tty_unlock(); 64696fd7ce5SGreg Kroah-Hartman /* 64796fd7ce5SGreg Kroah-Hartman * Make sure we don't change while someone holds a 64896fd7ce5SGreg Kroah-Hartman * reference to the line discipline. The TTY_LDISC bit 64996fd7ce5SGreg Kroah-Hartman * prevents anyone taking a reference once it is clear. 65096fd7ce5SGreg Kroah-Hartman * We need the lock to avoid racing reference takers. 65196fd7ce5SGreg Kroah-Hartman * 65296fd7ce5SGreg Kroah-Hartman * We must clear the TTY_LDISC bit here to avoid a livelock 65396fd7ce5SGreg Kroah-Hartman * with a userspace app continually trying to use the tty in 65496fd7ce5SGreg Kroah-Hartman * parallel to the change and re-referencing the tty. 65596fd7ce5SGreg Kroah-Hartman */ 65696fd7ce5SGreg Kroah-Hartman 65796fd7ce5SGreg Kroah-Hartman work = tty_ldisc_halt(tty); 65896fd7ce5SGreg Kroah-Hartman if (o_tty) 65996fd7ce5SGreg Kroah-Hartman o_work = tty_ldisc_halt(o_tty); 66096fd7ce5SGreg Kroah-Hartman 66196fd7ce5SGreg Kroah-Hartman /* 66296fd7ce5SGreg Kroah-Hartman * Wait for ->hangup_work and ->buf.work handlers to terminate. 66396fd7ce5SGreg Kroah-Hartman * We must drop the mutex here in case a hangup is also in process. 66496fd7ce5SGreg Kroah-Hartman */ 66596fd7ce5SGreg Kroah-Hartman 66696fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 66796fd7ce5SGreg Kroah-Hartman 6680a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 66996fd7ce5SGreg Kroah-Hartman 670df92d056SJiri Slaby retval = tty_ldisc_wait_idle(tty, 5 * HZ); 671100eeae2SJiri Slaby 67296fd7ce5SGreg Kroah-Hartman tty_lock(); 67396fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 674100eeae2SJiri Slaby 675100eeae2SJiri Slaby /* handle wait idle failure locked */ 676100eeae2SJiri Slaby if (retval) { 677100eeae2SJiri Slaby tty_ldisc_put(new_ldisc); 678100eeae2SJiri Slaby goto enable; 679100eeae2SJiri Slaby } 680100eeae2SJiri Slaby 68196fd7ce5SGreg Kroah-Hartman if (test_bit(TTY_HUPPED, &tty->flags)) { 68296fd7ce5SGreg Kroah-Hartman /* We were raced by the hangup method. It will have stomped 68396fd7ce5SGreg Kroah-Hartman the ldisc data and closed the ldisc down */ 68496fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_CHANGING, &tty->flags); 68596fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 68696fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 68796fd7ce5SGreg Kroah-Hartman tty_unlock(); 68896fd7ce5SGreg Kroah-Hartman return -EIO; 68996fd7ce5SGreg Kroah-Hartman } 69096fd7ce5SGreg Kroah-Hartman 69196fd7ce5SGreg Kroah-Hartman /* Shutdown the current discipline. */ 69296fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, o_ldisc); 69396fd7ce5SGreg Kroah-Hartman 69496fd7ce5SGreg Kroah-Hartman /* Now set up the new line discipline. */ 69596fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, new_ldisc); 69696fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 69796fd7ce5SGreg Kroah-Hartman 69896fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 69996fd7ce5SGreg Kroah-Hartman if (retval < 0) { 70096fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 70196fd7ce5SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 70296fd7ce5SGreg Kroah-Hartman tty_ldisc_restore(tty, o_ldisc); 70396fd7ce5SGreg Kroah-Hartman } 70496fd7ce5SGreg Kroah-Hartman 70596fd7ce5SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 70696fd7ce5SGreg Kroah-Hartman a reference to the old ldisc. If we ended up flipping back 70796fd7ce5SGreg Kroah-Hartman to the existing ldisc we have two references to it */ 70896fd7ce5SGreg Kroah-Hartman 70996fd7ce5SGreg Kroah-Hartman if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc) 71096fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 71196fd7ce5SGreg Kroah-Hartman 71296fd7ce5SGreg Kroah-Hartman tty_ldisc_put(o_ldisc); 71396fd7ce5SGreg Kroah-Hartman 714100eeae2SJiri Slaby enable: 71596fd7ce5SGreg Kroah-Hartman /* 71696fd7ce5SGreg Kroah-Hartman * Allow ldisc referencing to occur again 71796fd7ce5SGreg Kroah-Hartman */ 71896fd7ce5SGreg Kroah-Hartman 71996fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 72096fd7ce5SGreg Kroah-Hartman if (o_tty) 72196fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 72296fd7ce5SGreg Kroah-Hartman 72396fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 72496fd7ce5SGreg Kroah-Hartman already running */ 72596fd7ce5SGreg Kroah-Hartman if (work) 726f23eb2b2SLinus Torvalds schedule_work(&tty->buf.work); 72796fd7ce5SGreg Kroah-Hartman if (o_work) 728f23eb2b2SLinus Torvalds schedule_work(&o_tty->buf.work); 72996fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 73096fd7ce5SGreg Kroah-Hartman tty_unlock(); 73196fd7ce5SGreg Kroah-Hartman return retval; 73296fd7ce5SGreg Kroah-Hartman } 73396fd7ce5SGreg Kroah-Hartman 73496fd7ce5SGreg Kroah-Hartman /** 73596fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 73696fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 73796fd7ce5SGreg Kroah-Hartman * 73896fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 73996fd7ce5SGreg Kroah-Hartman */ 74096fd7ce5SGreg Kroah-Hartman 74196fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 74296fd7ce5SGreg Kroah-Hartman { 74396fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->termios_mutex); 74496fd7ce5SGreg Kroah-Hartman *tty->termios = tty->driver->init_termios; 74596fd7ce5SGreg Kroah-Hartman tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); 74696fd7ce5SGreg Kroah-Hartman tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); 74796fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->termios_mutex); 74896fd7ce5SGreg Kroah-Hartman } 74996fd7ce5SGreg Kroah-Hartman 75096fd7ce5SGreg Kroah-Hartman 75196fd7ce5SGreg Kroah-Hartman /** 75296fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 75396fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 75496fd7ce5SGreg Kroah-Hartman * @ldisc: line discipline to reinitialize 75596fd7ce5SGreg Kroah-Hartman * 75696fd7ce5SGreg Kroah-Hartman * Switch the tty to a line discipline and leave the ldisc 75796fd7ce5SGreg Kroah-Hartman * state closed 75896fd7ce5SGreg Kroah-Hartman */ 75996fd7ce5SGreg Kroah-Hartman 7601c95ba1eSPhilippe Rétornaz static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) 76196fd7ce5SGreg Kroah-Hartman { 7621c95ba1eSPhilippe Rétornaz struct tty_ldisc *ld = tty_ldisc_get(ldisc); 7631c95ba1eSPhilippe Rétornaz 7641c95ba1eSPhilippe Rétornaz if (IS_ERR(ld)) 7651c95ba1eSPhilippe Rétornaz return -1; 76696fd7ce5SGreg Kroah-Hartman 76796fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 76896fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 76996fd7ce5SGreg Kroah-Hartman tty->ldisc = NULL; 77096fd7ce5SGreg Kroah-Hartman /* 77196fd7ce5SGreg Kroah-Hartman * Switch the line discipline back 77296fd7ce5SGreg Kroah-Hartman */ 77396fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 77496fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, ldisc); 7751c95ba1eSPhilippe Rétornaz 7761c95ba1eSPhilippe Rétornaz return 0; 77796fd7ce5SGreg Kroah-Hartman } 77896fd7ce5SGreg Kroah-Hartman 77996fd7ce5SGreg Kroah-Hartman /** 78096fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 78196fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 78296fd7ce5SGreg Kroah-Hartman * 78396fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 78496fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 78596fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 78696fd7ce5SGreg Kroah-Hartman * 78796fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 78896fd7ce5SGreg Kroah-Hartman * careful to allow for this. 78996fd7ce5SGreg Kroah-Hartman * 79096fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 79196fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 79296fd7ce5SGreg Kroah-Hartman */ 79396fd7ce5SGreg Kroah-Hartman 79496fd7ce5SGreg Kroah-Hartman void tty_ldisc_hangup(struct tty_struct *tty) 79596fd7ce5SGreg Kroah-Hartman { 79696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 79796fd7ce5SGreg Kroah-Hartman int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS; 79896fd7ce5SGreg Kroah-Hartman int err = 0; 79996fd7ce5SGreg Kroah-Hartman 80096fd7ce5SGreg Kroah-Hartman /* 80196fd7ce5SGreg Kroah-Hartman * FIXME! What are the locking issues here? This may me overdoing 80296fd7ce5SGreg Kroah-Hartman * things... This question is especially important now that we've 80396fd7ce5SGreg Kroah-Hartman * removed the irqlock. 80496fd7ce5SGreg Kroah-Hartman */ 80596fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 80696fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 80796fd7ce5SGreg Kroah-Hartman /* We may have no line discipline at this point */ 80896fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 80996fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 81096fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 81196fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 81296fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 81396fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 81496fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 81596fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 81696fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 81796fd7ce5SGreg Kroah-Hartman } 81896fd7ce5SGreg Kroah-Hartman /* 81996fd7ce5SGreg Kroah-Hartman * FIXME: Once we trust the LDISC code better we can wait here for 82096fd7ce5SGreg Kroah-Hartman * ldisc completion and fix the driver call race 82196fd7ce5SGreg Kroah-Hartman */ 82296fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 82396fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 82496fd7ce5SGreg Kroah-Hartman /* 82596fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 82696fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 82796fd7ce5SGreg Kroah-Hartman * 82896fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 82996fd7ce5SGreg Kroah-Hartman */ 83096fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 83196fd7ce5SGreg Kroah-Hartman 83296fd7ce5SGreg Kroah-Hartman /* 83396fd7ce5SGreg Kroah-Hartman * this is like tty_ldisc_halt, but we need to give up 834f23eb2b2SLinus Torvalds * the BTM before calling cancel_work_sync, which may 835f23eb2b2SLinus Torvalds * need to wait for another function taking the BTM 83696fd7ce5SGreg Kroah-Hartman */ 83796fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC, &tty->flags); 83896fd7ce5SGreg Kroah-Hartman tty_unlock(); 839f23eb2b2SLinus Torvalds cancel_work_sync(&tty->buf.work); 84096fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 8410c73c08eSJiri Slaby retry: 84296fd7ce5SGreg Kroah-Hartman tty_lock(); 84396fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 84496fd7ce5SGreg Kroah-Hartman 84596fd7ce5SGreg Kroah-Hartman /* At this point we have a closed ldisc and we want to 84696fd7ce5SGreg Kroah-Hartman reopen it. We could defer this to the next open but 84796fd7ce5SGreg Kroah-Hartman it means auditing a lot of other paths so this is 84896fd7ce5SGreg Kroah-Hartman a FIXME */ 84996fd7ce5SGreg Kroah-Hartman if (tty->ldisc) { /* Not yet closed */ 8500c73c08eSJiri Slaby if (atomic_read(&tty->ldisc->users) != 1) { 8510c73c08eSJiri Slaby char cur_n[TASK_COMM_LEN], tty_n[64]; 8520c73c08eSJiri Slaby long timeout = 3 * HZ; 8530c73c08eSJiri Slaby tty_unlock(); 8540c73c08eSJiri Slaby 8550c73c08eSJiri Slaby while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { 8560c73c08eSJiri Slaby timeout = MAX_SCHEDULE_TIMEOUT; 8570c73c08eSJiri Slaby printk_ratelimited(KERN_WARNING 8580c73c08eSJiri Slaby "%s: waiting (%s) for %s took too long, but we keep waiting...\n", 8590c73c08eSJiri Slaby __func__, get_task_comm(cur_n, current), 8600c73c08eSJiri Slaby tty_name(tty, tty_n)); 8610c73c08eSJiri Slaby } 8620c73c08eSJiri Slaby mutex_unlock(&tty->ldisc_mutex); 8630c73c08eSJiri Slaby goto retry; 8640c73c08eSJiri Slaby } 86530042072SJiri Slaby 86696fd7ce5SGreg Kroah-Hartman if (reset == 0) { 8671c95ba1eSPhilippe Rétornaz 8681c95ba1eSPhilippe Rétornaz if (!tty_ldisc_reinit(tty, tty->termios->c_line)) 86996fd7ce5SGreg Kroah-Hartman err = tty_ldisc_open(tty, tty->ldisc); 8701c95ba1eSPhilippe Rétornaz else 8711c95ba1eSPhilippe Rétornaz err = 1; 87296fd7ce5SGreg Kroah-Hartman } 87396fd7ce5SGreg Kroah-Hartman /* If the re-open fails or we reset then go to N_TTY. The 87496fd7ce5SGreg Kroah-Hartman N_TTY open cannot fail */ 87596fd7ce5SGreg Kroah-Hartman if (reset || err) { 8761c95ba1eSPhilippe Rétornaz BUG_ON(tty_ldisc_reinit(tty, N_TTY)); 87796fd7ce5SGreg Kroah-Hartman WARN_ON(tty_ldisc_open(tty, tty->ldisc)); 87896fd7ce5SGreg Kroah-Hartman } 87996fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 88096fd7ce5SGreg Kroah-Hartman } 88196fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 88296fd7ce5SGreg Kroah-Hartman if (reset) 88396fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 88496fd7ce5SGreg Kroah-Hartman } 88596fd7ce5SGreg Kroah-Hartman 88696fd7ce5SGreg Kroah-Hartman /** 88796fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 88896fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 88996fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 89096fd7ce5SGreg Kroah-Hartman * 89196fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 89296fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 89396fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 89496fd7ce5SGreg Kroah-Hartman */ 89596fd7ce5SGreg Kroah-Hartman 89696fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 89796fd7ce5SGreg Kroah-Hartman { 89896fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty->ldisc; 89996fd7ce5SGreg Kroah-Hartman int retval; 90096fd7ce5SGreg Kroah-Hartman 90196fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(tty, ld); 90296fd7ce5SGreg Kroah-Hartman if (retval) 90396fd7ce5SGreg Kroah-Hartman return retval; 90496fd7ce5SGreg Kroah-Hartman 90596fd7ce5SGreg Kroah-Hartman if (o_tty) { 90696fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 90796fd7ce5SGreg Kroah-Hartman if (retval) { 90896fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, ld); 90996fd7ce5SGreg Kroah-Hartman return retval; 91096fd7ce5SGreg Kroah-Hartman } 91196fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(o_tty); 91296fd7ce5SGreg Kroah-Hartman } 91396fd7ce5SGreg Kroah-Hartman tty_ldisc_enable(tty); 91496fd7ce5SGreg Kroah-Hartman return 0; 91596fd7ce5SGreg Kroah-Hartman } 91696fd7ce5SGreg Kroah-Hartman /** 91796fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 91896fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 91996fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 92096fd7ce5SGreg Kroah-Hartman * 92196fd7ce5SGreg Kroah-Hartman * Called during the final close of a tty/pty pair in order to shut down 92296fd7ce5SGreg Kroah-Hartman * the line discpline layer. On exit the ldisc assigned is N_TTY and the 92396fd7ce5SGreg Kroah-Hartman * ldisc has not been opened. 92496fd7ce5SGreg Kroah-Hartman */ 92596fd7ce5SGreg Kroah-Hartman 92696fd7ce5SGreg Kroah-Hartman void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) 92796fd7ce5SGreg Kroah-Hartman { 92896fd7ce5SGreg Kroah-Hartman /* 92996fd7ce5SGreg Kroah-Hartman * Prevent flush_to_ldisc() from rescheduling the work for later. Then 93096fd7ce5SGreg Kroah-Hartman * kill any delayed work. As this is the final close it does not 93196fd7ce5SGreg Kroah-Hartman * race with the set_ldisc code path. 93296fd7ce5SGreg Kroah-Hartman */ 93396fd7ce5SGreg Kroah-Hartman 93496fd7ce5SGreg Kroah-Hartman tty_unlock(); 93596fd7ce5SGreg Kroah-Hartman tty_ldisc_halt(tty); 9360a1f1a0bSTejun Heo tty_ldisc_flush_works(tty); 93796fd7ce5SGreg Kroah-Hartman tty_lock(); 93896fd7ce5SGreg Kroah-Hartman 93996fd7ce5SGreg Kroah-Hartman mutex_lock(&tty->ldisc_mutex); 94096fd7ce5SGreg Kroah-Hartman /* 94196fd7ce5SGreg Kroah-Hartman * Now kill off the ldisc 94296fd7ce5SGreg Kroah-Hartman */ 94396fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 94496fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 94596fd7ce5SGreg Kroah-Hartman /* Force an oops if we mess this up */ 94696fd7ce5SGreg Kroah-Hartman tty->ldisc = NULL; 94796fd7ce5SGreg Kroah-Hartman 94896fd7ce5SGreg Kroah-Hartman /* Ensure the next open requests the N_TTY ldisc */ 94996fd7ce5SGreg Kroah-Hartman tty_set_termios_ldisc(tty, N_TTY); 95096fd7ce5SGreg Kroah-Hartman mutex_unlock(&tty->ldisc_mutex); 95196fd7ce5SGreg Kroah-Hartman 95296fd7ce5SGreg Kroah-Hartman /* This will need doing differently if we need to lock */ 95396fd7ce5SGreg Kroah-Hartman if (o_tty) 95496fd7ce5SGreg Kroah-Hartman tty_ldisc_release(o_tty, NULL); 95596fd7ce5SGreg Kroah-Hartman 95696fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 95796fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 95896fd7ce5SGreg Kroah-Hartman } 95996fd7ce5SGreg Kroah-Hartman 96096fd7ce5SGreg Kroah-Hartman /** 96196fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 96296fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 96396fd7ce5SGreg Kroah-Hartman * 96496fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 96596fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 96696fd7ce5SGreg Kroah-Hartman */ 96796fd7ce5SGreg Kroah-Hartman 96896fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 96996fd7ce5SGreg Kroah-Hartman { 97096fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_get(N_TTY); 97196fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 97296fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 97396fd7ce5SGreg Kroah-Hartman tty_ldisc_assign(tty, ld); 97496fd7ce5SGreg Kroah-Hartman } 97596fd7ce5SGreg Kroah-Hartman 9766716671dSJiri Slaby /** 9776716671dSJiri Slaby * tty_ldisc_init - ldisc cleanup for new tty 9786716671dSJiri Slaby * @tty: tty that was allocated recently 9796716671dSJiri Slaby * 9806716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 9816716671dSJiri Slaby * this call is made. 9826716671dSJiri Slaby */ 9836716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 9846716671dSJiri Slaby { 9856716671dSJiri Slaby put_ldisc(tty->ldisc); 9866716671dSJiri Slaby tty_ldisc_assign(tty, NULL); 9876716671dSJiri Slaby } 9886716671dSJiri Slaby 98996fd7ce5SGreg Kroah-Hartman void tty_ldisc_begin(void) 99096fd7ce5SGreg Kroah-Hartman { 99196fd7ce5SGreg Kroah-Hartman /* Setup the default TTY line discipline. */ 99296fd7ce5SGreg Kroah-Hartman (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); 99396fd7ce5SGreg Kroah-Hartman } 994