1e3b3d0f5SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 296fd7ce5SGreg Kroah-Hartman #include <linux/types.h> 396fd7ce5SGreg Kroah-Hartman #include <linux/errno.h> 48b3ffa17SJiri Slaby #include <linux/kmod.h> 596fd7ce5SGreg Kroah-Hartman #include <linux/sched.h> 696fd7ce5SGreg Kroah-Hartman #include <linux/interrupt.h> 796fd7ce5SGreg Kroah-Hartman #include <linux/tty.h> 896fd7ce5SGreg Kroah-Hartman #include <linux/tty_driver.h> 996fd7ce5SGreg Kroah-Hartman #include <linux/file.h> 1096fd7ce5SGreg Kroah-Hartman #include <linux/mm.h> 1196fd7ce5SGreg Kroah-Hartman #include <linux/string.h> 1296fd7ce5SGreg Kroah-Hartman #include <linux/slab.h> 1396fd7ce5SGreg Kroah-Hartman #include <linux/poll.h> 1496fd7ce5SGreg Kroah-Hartman #include <linux/proc_fs.h> 1596fd7ce5SGreg Kroah-Hartman #include <linux/module.h> 1696fd7ce5SGreg Kroah-Hartman #include <linux/device.h> 1796fd7ce5SGreg Kroah-Hartman #include <linux/wait.h> 1896fd7ce5SGreg Kroah-Hartman #include <linux/bitops.h> 1996fd7ce5SGreg Kroah-Hartman #include <linux/seq_file.h> 2096fd7ce5SGreg Kroah-Hartman #include <linux/uaccess.h> 210c73c08eSJiri Slaby #include <linux/ratelimit.h> 2296fd7ce5SGreg Kroah-Hartman 23fc575ee6SPeter Hurley #undef LDISC_DEBUG_HANGUP 24fc575ee6SPeter Hurley 25fc575ee6SPeter Hurley #ifdef LDISC_DEBUG_HANGUP 260a6adc13SPeter Hurley #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) 27fc575ee6SPeter Hurley #else 28fc575ee6SPeter Hurley #define tty_ldisc_debug(tty, f, args...) 29fc575ee6SPeter Hurley #endif 30fc575ee6SPeter Hurley 31d2c43890SPeter Hurley /* lockdep nested classes for tty->ldisc_sem */ 32d2c43890SPeter Hurley enum { 33d2c43890SPeter Hurley LDISC_SEM_NORMAL, 34d2c43890SPeter Hurley LDISC_SEM_OTHER, 35d2c43890SPeter Hurley }; 36d2c43890SPeter Hurley 37d2c43890SPeter Hurley 3896fd7ce5SGreg Kroah-Hartman /* 3996fd7ce5SGreg Kroah-Hartman * This guards the refcounted line discipline lists. The lock 4096fd7ce5SGreg Kroah-Hartman * must be taken with irqs off because there are hangup path 4196fd7ce5SGreg Kroah-Hartman * callers who will do ldisc lookups and cannot sleep. 4296fd7ce5SGreg Kroah-Hartman */ 4396fd7ce5SGreg Kroah-Hartman 44137084bbSPeter Hurley static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); 4596fd7ce5SGreg Kroah-Hartman /* Line disc dispatch table */ 4696fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; 4796fd7ce5SGreg Kroah-Hartman 4896fd7ce5SGreg Kroah-Hartman /** 4996fd7ce5SGreg Kroah-Hartman * tty_register_ldisc - install a line discipline 5096fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 5196fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 5296fd7ce5SGreg Kroah-Hartman * 5396fd7ce5SGreg Kroah-Hartman * Installs a new line discipline into the kernel. The discipline 5496fd7ce5SGreg Kroah-Hartman * is set up as unreferenced and then made available to the kernel 5596fd7ce5SGreg Kroah-Hartman * from this point onwards. 5696fd7ce5SGreg Kroah-Hartman * 5796fd7ce5SGreg Kroah-Hartman * Locking: 58137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 5996fd7ce5SGreg Kroah-Hartman */ 6096fd7ce5SGreg Kroah-Hartman 6196fd7ce5SGreg Kroah-Hartman int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) 6296fd7ce5SGreg Kroah-Hartman { 6396fd7ce5SGreg Kroah-Hartman unsigned long flags; 6496fd7ce5SGreg Kroah-Hartman int ret = 0; 6596fd7ce5SGreg Kroah-Hartman 6696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 6796fd7ce5SGreg Kroah-Hartman return -EINVAL; 6896fd7ce5SGreg Kroah-Hartman 69137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 7096fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = new_ldisc; 7196fd7ce5SGreg Kroah-Hartman new_ldisc->num = disc; 7296fd7ce5SGreg Kroah-Hartman new_ldisc->refcount = 0; 73137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 7496fd7ce5SGreg Kroah-Hartman 7596fd7ce5SGreg Kroah-Hartman return ret; 7696fd7ce5SGreg Kroah-Hartman } 7796fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_register_ldisc); 7896fd7ce5SGreg Kroah-Hartman 7996fd7ce5SGreg Kroah-Hartman /** 8096fd7ce5SGreg Kroah-Hartman * tty_unregister_ldisc - unload a line discipline 8196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 8296fd7ce5SGreg Kroah-Hartman * @new_ldisc: pointer to the ldisc object 8396fd7ce5SGreg Kroah-Hartman * 8496fd7ce5SGreg Kroah-Hartman * Remove a line discipline from the kernel providing it is not 8596fd7ce5SGreg Kroah-Hartman * currently in use. 8696fd7ce5SGreg Kroah-Hartman * 8796fd7ce5SGreg Kroah-Hartman * Locking: 88137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 8996fd7ce5SGreg Kroah-Hartman */ 9096fd7ce5SGreg Kroah-Hartman 9196fd7ce5SGreg Kroah-Hartman int tty_unregister_ldisc(int disc) 9296fd7ce5SGreg Kroah-Hartman { 9396fd7ce5SGreg Kroah-Hartman unsigned long flags; 9496fd7ce5SGreg Kroah-Hartman int ret = 0; 9596fd7ce5SGreg Kroah-Hartman 9696fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 9796fd7ce5SGreg Kroah-Hartman return -EINVAL; 9896fd7ce5SGreg Kroah-Hartman 99137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 10096fd7ce5SGreg Kroah-Hartman if (tty_ldiscs[disc]->refcount) 10196fd7ce5SGreg Kroah-Hartman ret = -EBUSY; 10296fd7ce5SGreg Kroah-Hartman else 10396fd7ce5SGreg Kroah-Hartman tty_ldiscs[disc] = NULL; 104137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 10596fd7ce5SGreg Kroah-Hartman 10696fd7ce5SGreg Kroah-Hartman return ret; 10796fd7ce5SGreg Kroah-Hartman } 10896fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL(tty_unregister_ldisc); 10996fd7ce5SGreg Kroah-Hartman 11096fd7ce5SGreg Kroah-Hartman static struct tty_ldisc_ops *get_ldops(int disc) 11196fd7ce5SGreg Kroah-Hartman { 11296fd7ce5SGreg Kroah-Hartman unsigned long flags; 11396fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops, *ret; 11496fd7ce5SGreg Kroah-Hartman 115137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 11696fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EINVAL); 11796fd7ce5SGreg Kroah-Hartman ldops = tty_ldiscs[disc]; 11896fd7ce5SGreg Kroah-Hartman if (ldops) { 11996fd7ce5SGreg Kroah-Hartman ret = ERR_PTR(-EAGAIN); 12096fd7ce5SGreg Kroah-Hartman if (try_module_get(ldops->owner)) { 12196fd7ce5SGreg Kroah-Hartman ldops->refcount++; 12296fd7ce5SGreg Kroah-Hartman ret = ldops; 12396fd7ce5SGreg Kroah-Hartman } 12496fd7ce5SGreg Kroah-Hartman } 125137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 12696fd7ce5SGreg Kroah-Hartman return ret; 12796fd7ce5SGreg Kroah-Hartman } 12896fd7ce5SGreg Kroah-Hartman 12996fd7ce5SGreg Kroah-Hartman static void put_ldops(struct tty_ldisc_ops *ldops) 13096fd7ce5SGreg Kroah-Hartman { 13196fd7ce5SGreg Kroah-Hartman unsigned long flags; 13296fd7ce5SGreg Kroah-Hartman 133137084bbSPeter Hurley raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); 13496fd7ce5SGreg Kroah-Hartman ldops->refcount--; 13596fd7ce5SGreg Kroah-Hartman module_put(ldops->owner); 136137084bbSPeter Hurley raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); 13796fd7ce5SGreg Kroah-Hartman } 13896fd7ce5SGreg Kroah-Hartman 13996fd7ce5SGreg Kroah-Hartman /** 14096fd7ce5SGreg Kroah-Hartman * tty_ldisc_get - take a reference to an ldisc 14196fd7ce5SGreg Kroah-Hartman * @disc: ldisc number 14296fd7ce5SGreg Kroah-Hartman * 14396fd7ce5SGreg Kroah-Hartman * Takes a reference to a line discipline. Deals with refcounts and 144c0cc1c5dSPeter Hurley * module locking counts. 145c0cc1c5dSPeter Hurley * 146c0cc1c5dSPeter Hurley * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or 147c0cc1c5dSPeter Hurley * if the discipline is not registered 148c0cc1c5dSPeter Hurley * -EAGAIN if request_module() failed to load or register the 149c0cc1c5dSPeter Hurley * the discipline 150c0cc1c5dSPeter Hurley * -ENOMEM if allocation failure 151c0cc1c5dSPeter Hurley * 152c0cc1c5dSPeter Hurley * Otherwise, returns a pointer to the discipline and bumps the 153c0cc1c5dSPeter Hurley * ref count 15496fd7ce5SGreg Kroah-Hartman * 15596fd7ce5SGreg Kroah-Hartman * Locking: 156137084bbSPeter Hurley * takes tty_ldiscs_lock to guard against ldisc races 15796fd7ce5SGreg Kroah-Hartman */ 15896fd7ce5SGreg Kroah-Hartman 15936697529SPeter Hurley static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) 16096fd7ce5SGreg Kroah-Hartman { 16196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 16296fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 16396fd7ce5SGreg Kroah-Hartman 16496fd7ce5SGreg Kroah-Hartman if (disc < N_TTY || disc >= NR_LDISCS) 16596fd7ce5SGreg Kroah-Hartman return ERR_PTR(-EINVAL); 16696fd7ce5SGreg Kroah-Hartman 16796fd7ce5SGreg Kroah-Hartman /* 16896fd7ce5SGreg Kroah-Hartman * Get the ldisc ops - we may need to request them to be loaded 16996fd7ce5SGreg Kroah-Hartman * dynamically and try again. 17096fd7ce5SGreg Kroah-Hartman */ 17196fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 17296fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) { 17396fd7ce5SGreg Kroah-Hartman request_module("tty-ldisc-%d", disc); 17496fd7ce5SGreg Kroah-Hartman ldops = get_ldops(disc); 17596fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 17696fd7ce5SGreg Kroah-Hartman return ERR_CAST(ldops); 17796fd7ce5SGreg Kroah-Hartman } 17896fd7ce5SGreg Kroah-Hartman 17996fd7ce5SGreg Kroah-Hartman ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); 18096fd7ce5SGreg Kroah-Hartman if (ld == NULL) { 18196fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 18296fd7ce5SGreg Kroah-Hartman return ERR_PTR(-ENOMEM); 18396fd7ce5SGreg Kroah-Hartman } 18496fd7ce5SGreg Kroah-Hartman 18596fd7ce5SGreg Kroah-Hartman ld->ops = ldops; 18636697529SPeter Hurley ld->tty = tty; 1871541f845SIvo Sieben 18896fd7ce5SGreg Kroah-Hartman return ld; 18996fd7ce5SGreg Kroah-Hartman } 19096fd7ce5SGreg Kroah-Hartman 191734de249SPeter Hurley /** 192734de249SPeter Hurley * tty_ldisc_put - release the ldisc 193734de249SPeter Hurley * 194734de249SPeter Hurley * Complement of tty_ldisc_get(). 195734de249SPeter Hurley */ 196cb128f69SDenys Vlasenko static void tty_ldisc_put(struct tty_ldisc *ld) 197734de249SPeter Hurley { 198734de249SPeter Hurley if (WARN_ON_ONCE(!ld)) 199734de249SPeter Hurley return; 200734de249SPeter Hurley 20136697529SPeter Hurley put_ldops(ld->ops); 202734de249SPeter Hurley kfree(ld); 203734de249SPeter Hurley } 204734de249SPeter Hurley 20596fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) 20696fd7ce5SGreg Kroah-Hartman { 20796fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 20896fd7ce5SGreg Kroah-Hartman } 20996fd7ce5SGreg Kroah-Hartman 21096fd7ce5SGreg Kroah-Hartman static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) 21196fd7ce5SGreg Kroah-Hartman { 21296fd7ce5SGreg Kroah-Hartman (*pos)++; 21396fd7ce5SGreg Kroah-Hartman return (*pos < NR_LDISCS) ? pos : NULL; 21496fd7ce5SGreg Kroah-Hartman } 21596fd7ce5SGreg Kroah-Hartman 21696fd7ce5SGreg Kroah-Hartman static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) 21796fd7ce5SGreg Kroah-Hartman { 21896fd7ce5SGreg Kroah-Hartman } 21996fd7ce5SGreg Kroah-Hartman 22096fd7ce5SGreg Kroah-Hartman static int tty_ldiscs_seq_show(struct seq_file *m, void *v) 22196fd7ce5SGreg Kroah-Hartman { 22296fd7ce5SGreg Kroah-Hartman int i = *(loff_t *)v; 22396fd7ce5SGreg Kroah-Hartman struct tty_ldisc_ops *ldops; 22496fd7ce5SGreg Kroah-Hartman 22596fd7ce5SGreg Kroah-Hartman ldops = get_ldops(i); 22696fd7ce5SGreg Kroah-Hartman if (IS_ERR(ldops)) 22796fd7ce5SGreg Kroah-Hartman return 0; 22896fd7ce5SGreg Kroah-Hartman seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); 22996fd7ce5SGreg Kroah-Hartman put_ldops(ldops); 23096fd7ce5SGreg Kroah-Hartman return 0; 23196fd7ce5SGreg Kroah-Hartman } 23296fd7ce5SGreg Kroah-Hartman 23396fd7ce5SGreg Kroah-Hartman static const struct seq_operations tty_ldiscs_seq_ops = { 23496fd7ce5SGreg Kroah-Hartman .start = tty_ldiscs_seq_start, 23596fd7ce5SGreg Kroah-Hartman .next = tty_ldiscs_seq_next, 23696fd7ce5SGreg Kroah-Hartman .stop = tty_ldiscs_seq_stop, 23796fd7ce5SGreg Kroah-Hartman .show = tty_ldiscs_seq_show, 23896fd7ce5SGreg Kroah-Hartman }; 23996fd7ce5SGreg Kroah-Hartman 24096fd7ce5SGreg Kroah-Hartman static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) 24196fd7ce5SGreg Kroah-Hartman { 24296fd7ce5SGreg Kroah-Hartman return seq_open(file, &tty_ldiscs_seq_ops); 24396fd7ce5SGreg Kroah-Hartman } 24496fd7ce5SGreg Kroah-Hartman 24596fd7ce5SGreg Kroah-Hartman const struct file_operations tty_ldiscs_proc_fops = { 24696fd7ce5SGreg Kroah-Hartman .owner = THIS_MODULE, 24796fd7ce5SGreg Kroah-Hartman .open = proc_tty_ldiscs_open, 24896fd7ce5SGreg Kroah-Hartman .read = seq_read, 24996fd7ce5SGreg Kroah-Hartman .llseek = seq_lseek, 25096fd7ce5SGreg Kroah-Hartman .release = seq_release, 25196fd7ce5SGreg Kroah-Hartman }; 25296fd7ce5SGreg Kroah-Hartman 25396fd7ce5SGreg Kroah-Hartman /** 25496fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref_wait - wait for the tty ldisc 25596fd7ce5SGreg Kroah-Hartman * @tty: tty device 25696fd7ce5SGreg Kroah-Hartman * 25796fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 25896fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 25996fd7ce5SGreg Kroah-Hartman * wait patiently until it changes. 26096fd7ce5SGreg Kroah-Hartman * 261892d1fa7SPeter Hurley * Returns: NULL if the tty has been hungup and not re-opened with 262892d1fa7SPeter Hurley * a new file descriptor, otherwise valid ldisc reference 263892d1fa7SPeter Hurley * 26496fd7ce5SGreg Kroah-Hartman * Note: Must not be called from an IRQ/timer context. The caller 26596fd7ce5SGreg Kroah-Hartman * must also be careful not to hold other locks that will deadlock 26696fd7ce5SGreg Kroah-Hartman * against a discipline change, such as an existing ldisc reference 26796fd7ce5SGreg Kroah-Hartman * (which we check for) 26896fd7ce5SGreg Kroah-Hartman * 269e55afd11SPeter Hurley * Note: a file_operations routine (read/poll/write) should use this 270e55afd11SPeter Hurley * function to wait for any ldisc lifetime events to finish. 27196fd7ce5SGreg Kroah-Hartman */ 27296fd7ce5SGreg Kroah-Hartman 27396fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) 27496fd7ce5SGreg Kroah-Hartman { 275a4a3e061SDmitry Vyukov struct tty_ldisc *ld; 276a4a3e061SDmitry Vyukov 27736697529SPeter Hurley ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); 278a4a3e061SDmitry Vyukov ld = tty->ldisc; 279a4a3e061SDmitry Vyukov if (!ld) 280a570a49aSPeter Hurley ldsem_up_read(&tty->ldisc_sem); 281a4a3e061SDmitry Vyukov return ld; 28296fd7ce5SGreg Kroah-Hartman } 28396fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); 28496fd7ce5SGreg Kroah-Hartman 28596fd7ce5SGreg Kroah-Hartman /** 28696fd7ce5SGreg Kroah-Hartman * tty_ldisc_ref - get the tty ldisc 28796fd7ce5SGreg Kroah-Hartman * @tty: tty device 28896fd7ce5SGreg Kroah-Hartman * 28996fd7ce5SGreg Kroah-Hartman * Dereference the line discipline for the terminal and take a 29096fd7ce5SGreg Kroah-Hartman * reference to it. If the line discipline is in flux then 29196fd7ce5SGreg Kroah-Hartman * return NULL. Can be called from IRQ and timer functions. 29296fd7ce5SGreg Kroah-Hartman */ 29396fd7ce5SGreg Kroah-Hartman 29496fd7ce5SGreg Kroah-Hartman struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) 29596fd7ce5SGreg Kroah-Hartman { 29636697529SPeter Hurley struct tty_ldisc *ld = NULL; 29736697529SPeter Hurley 29836697529SPeter Hurley if (ldsem_down_read_trylock(&tty->ldisc_sem)) { 29936697529SPeter Hurley ld = tty->ldisc; 30036697529SPeter Hurley if (!ld) 30136697529SPeter Hurley ldsem_up_read(&tty->ldisc_sem); 30236697529SPeter Hurley } 30336697529SPeter Hurley return ld; 30496fd7ce5SGreg Kroah-Hartman } 30596fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_ref); 30696fd7ce5SGreg Kroah-Hartman 30796fd7ce5SGreg Kroah-Hartman /** 30896fd7ce5SGreg Kroah-Hartman * tty_ldisc_deref - free a tty ldisc reference 30996fd7ce5SGreg Kroah-Hartman * @ld: reference to free up 31096fd7ce5SGreg Kroah-Hartman * 31196fd7ce5SGreg Kroah-Hartman * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May 31296fd7ce5SGreg Kroah-Hartman * be called in IRQ context. 31396fd7ce5SGreg Kroah-Hartman */ 31496fd7ce5SGreg Kroah-Hartman 31596fd7ce5SGreg Kroah-Hartman void tty_ldisc_deref(struct tty_ldisc *ld) 31696fd7ce5SGreg Kroah-Hartman { 31736697529SPeter Hurley ldsem_up_read(&ld->tty->ldisc_sem); 31896fd7ce5SGreg Kroah-Hartman } 31996fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_deref); 32096fd7ce5SGreg Kroah-Hartman 321d2c43890SPeter Hurley 322c2bb524bSPeter Hurley static inline int 323e80a10eeSPeter Hurley __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 324d2c43890SPeter Hurley { 325d2c43890SPeter Hurley return ldsem_down_write(&tty->ldisc_sem, timeout); 326d2c43890SPeter Hurley } 327d2c43890SPeter Hurley 328c2bb524bSPeter Hurley static inline int 329e80a10eeSPeter Hurley __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) 330d2c43890SPeter Hurley { 331d2c43890SPeter Hurley return ldsem_down_write_nested(&tty->ldisc_sem, 332d2c43890SPeter Hurley LDISC_SEM_OTHER, timeout); 333d2c43890SPeter Hurley } 334d2c43890SPeter Hurley 335e80a10eeSPeter Hurley static inline void __tty_ldisc_unlock(struct tty_struct *tty) 336d2c43890SPeter Hurley { 33752772ea6SGuillaume Gomez ldsem_up_write(&tty->ldisc_sem); 338d2c43890SPeter Hurley } 339d2c43890SPeter Hurley 340b027e229SGaurav Kohli int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) 341fae76e9aSPeter Hurley { 342fae76e9aSPeter Hurley int ret; 343fae76e9aSPeter Hurley 344fae76e9aSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 345fae76e9aSPeter Hurley if (!ret) 346fae76e9aSPeter Hurley return -EBUSY; 347fae76e9aSPeter Hurley set_bit(TTY_LDISC_HALTED, &tty->flags); 348fae76e9aSPeter Hurley return 0; 349fae76e9aSPeter Hurley } 350fae76e9aSPeter Hurley 351b027e229SGaurav Kohli void tty_ldisc_unlock(struct tty_struct *tty) 352fae76e9aSPeter Hurley { 353fae76e9aSPeter Hurley clear_bit(TTY_LDISC_HALTED, &tty->flags); 354fae76e9aSPeter Hurley __tty_ldisc_unlock(tty); 355fae76e9aSPeter Hurley } 356fae76e9aSPeter Hurley 357c2bb524bSPeter Hurley static int 358d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, 359d2c43890SPeter Hurley unsigned long timeout) 360d2c43890SPeter Hurley { 361d2c43890SPeter Hurley int ret; 362d2c43890SPeter Hurley 363d2c43890SPeter Hurley if (tty < tty2) { 364e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 365d2c43890SPeter Hurley if (ret) { 366e80a10eeSPeter Hurley ret = __tty_ldisc_lock_nested(tty2, timeout); 367d2c43890SPeter Hurley if (!ret) 368e80a10eeSPeter Hurley __tty_ldisc_unlock(tty); 369d2c43890SPeter Hurley } 370d2c43890SPeter Hurley } else { 371d2c43890SPeter Hurley /* if this is possible, it has lots of implications */ 372d2c43890SPeter Hurley WARN_ON_ONCE(tty == tty2); 373d2c43890SPeter Hurley if (tty2 && tty != tty2) { 374e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty2, timeout); 375d2c43890SPeter Hurley if (ret) { 376e80a10eeSPeter Hurley ret = __tty_ldisc_lock_nested(tty, timeout); 377d2c43890SPeter Hurley if (!ret) 378e80a10eeSPeter Hurley __tty_ldisc_unlock(tty2); 379d2c43890SPeter Hurley } 380d2c43890SPeter Hurley } else 381e80a10eeSPeter Hurley ret = __tty_ldisc_lock(tty, timeout); 382d2c43890SPeter Hurley } 383d2c43890SPeter Hurley 384d2c43890SPeter Hurley if (!ret) 385d2c43890SPeter Hurley return -EBUSY; 386d2c43890SPeter Hurley 387d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty->flags); 388d2c43890SPeter Hurley if (tty2) 389d2c43890SPeter Hurley set_bit(TTY_LDISC_HALTED, &tty2->flags); 390d2c43890SPeter Hurley return 0; 391d2c43890SPeter Hurley } 392d2c43890SPeter Hurley 393c2bb524bSPeter Hurley static void tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) 394d2c43890SPeter Hurley { 395d2c43890SPeter Hurley tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); 396d2c43890SPeter Hurley } 397d2c43890SPeter Hurley 398c2bb524bSPeter Hurley static void tty_ldisc_unlock_pair(struct tty_struct *tty, 399d2c43890SPeter Hurley struct tty_struct *tty2) 400d2c43890SPeter Hurley { 401e80a10eeSPeter Hurley __tty_ldisc_unlock(tty); 402d2c43890SPeter Hurley if (tty2) 403e80a10eeSPeter Hurley __tty_ldisc_unlock(tty2); 404d2c43890SPeter Hurley } 405d2c43890SPeter Hurley 40696fd7ce5SGreg Kroah-Hartman /** 40796fd7ce5SGreg Kroah-Hartman * tty_ldisc_flush - flush line discipline queue 40896fd7ce5SGreg Kroah-Hartman * @tty: tty 40996fd7ce5SGreg Kroah-Hartman * 41086c80a8eSPeter Hurley * Flush the line discipline queue (if any) and the tty flip buffers 41186c80a8eSPeter Hurley * for this tty. 41296fd7ce5SGreg Kroah-Hartman */ 41396fd7ce5SGreg Kroah-Hartman 41496fd7ce5SGreg Kroah-Hartman void tty_ldisc_flush(struct tty_struct *tty) 41596fd7ce5SGreg Kroah-Hartman { 41696fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld = tty_ldisc_ref(tty); 41786c80a8eSPeter Hurley 41886c80a8eSPeter Hurley tty_buffer_flush(tty, ld); 41986c80a8eSPeter Hurley if (ld) 42096fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 42196fd7ce5SGreg Kroah-Hartman } 42296fd7ce5SGreg Kroah-Hartman EXPORT_SYMBOL_GPL(tty_ldisc_flush); 42396fd7ce5SGreg Kroah-Hartman 42496fd7ce5SGreg Kroah-Hartman /** 42596fd7ce5SGreg Kroah-Hartman * tty_set_termios_ldisc - set ldisc field 42696fd7ce5SGreg Kroah-Hartman * @tty: tty structure 427c12da96fSPeter Hurley * @disc: line discipline number 42896fd7ce5SGreg Kroah-Hartman * 42996fd7ce5SGreg Kroah-Hartman * This is probably overkill for real world processors but 43096fd7ce5SGreg Kroah-Hartman * they are not on hot paths so a little discipline won't do 43196fd7ce5SGreg Kroah-Hartman * any harm. 43296fd7ce5SGreg Kroah-Hartman * 433dd42bf11SPeter Hurley * The line discipline-related tty_struct fields are reset to 434dd42bf11SPeter Hurley * prevent the ldisc driver from re-using stale information for 435dd42bf11SPeter Hurley * the new ldisc instance. 436dd42bf11SPeter Hurley * 4376a1c0680SPeter Hurley * Locking: takes termios_rwsem 43896fd7ce5SGreg Kroah-Hartman */ 43996fd7ce5SGreg Kroah-Hartman 440c12da96fSPeter Hurley static void tty_set_termios_ldisc(struct tty_struct *tty, int disc) 44196fd7ce5SGreg Kroah-Hartman { 4426a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 443c12da96fSPeter Hurley tty->termios.c_line = disc; 4446a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 445dd42bf11SPeter Hurley 446dd42bf11SPeter Hurley tty->disc_data = NULL; 447dd42bf11SPeter Hurley tty->receive_room = 0; 44896fd7ce5SGreg Kroah-Hartman } 44996fd7ce5SGreg Kroah-Hartman 45096fd7ce5SGreg Kroah-Hartman /** 45196fd7ce5SGreg Kroah-Hartman * tty_ldisc_open - open a line discipline 45296fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 45396fd7ce5SGreg Kroah-Hartman * @ld: discipline to open 45496fd7ce5SGreg Kroah-Hartman * 45596fd7ce5SGreg Kroah-Hartman * A helper opening method. Also a convenient debugging and check 45696fd7ce5SGreg Kroah-Hartman * point. 45796fd7ce5SGreg Kroah-Hartman * 45896fd7ce5SGreg Kroah-Hartman * Locking: always called with BTM already held. 45996fd7ce5SGreg Kroah-Hartman */ 46096fd7ce5SGreg Kroah-Hartman 46196fd7ce5SGreg Kroah-Hartman static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 46296fd7ce5SGreg Kroah-Hartman { 46396fd7ce5SGreg Kroah-Hartman WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); 46496fd7ce5SGreg Kroah-Hartman if (ld->ops->open) { 46596fd7ce5SGreg Kroah-Hartman int ret; 46696fd7ce5SGreg Kroah-Hartman /* BTM here locks versus a hangup event */ 46796fd7ce5SGreg Kroah-Hartman ret = ld->ops->open(tty); 4687f90cfc5SJiri Slaby if (ret) 4697f90cfc5SJiri Slaby clear_bit(TTY_LDISC_OPEN, &tty->flags); 470fb6edc91SPeter Hurley 471a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: opened\n", ld); 47296fd7ce5SGreg Kroah-Hartman return ret; 47396fd7ce5SGreg Kroah-Hartman } 47496fd7ce5SGreg Kroah-Hartman return 0; 47596fd7ce5SGreg Kroah-Hartman } 47696fd7ce5SGreg Kroah-Hartman 47796fd7ce5SGreg Kroah-Hartman /** 47896fd7ce5SGreg Kroah-Hartman * tty_ldisc_close - close a line discipline 47996fd7ce5SGreg Kroah-Hartman * @tty: tty we are opening the ldisc on 48096fd7ce5SGreg Kroah-Hartman * @ld: discipline to close 48196fd7ce5SGreg Kroah-Hartman * 48296fd7ce5SGreg Kroah-Hartman * A helper close method. Also a convenient debugging and check 48396fd7ce5SGreg Kroah-Hartman * point. 48496fd7ce5SGreg Kroah-Hartman */ 48596fd7ce5SGreg Kroah-Hartman 48696fd7ce5SGreg Kroah-Hartman static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) 48796fd7ce5SGreg Kroah-Hartman { 48896fd7ce5SGreg Kroah-Hartman WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); 48996fd7ce5SGreg Kroah-Hartman clear_bit(TTY_LDISC_OPEN, &tty->flags); 49096fd7ce5SGreg Kroah-Hartman if (ld->ops->close) 49196fd7ce5SGreg Kroah-Hartman ld->ops->close(tty); 492a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: closed\n", ld); 49396fd7ce5SGreg Kroah-Hartman } 49496fd7ce5SGreg Kroah-Hartman 49596fd7ce5SGreg Kroah-Hartman /** 4968a8dabf2SAlan Cox * tty_ldisc_failto - helper for ldisc failback 4978a8dabf2SAlan Cox * @tty: tty to open the ldisc on 4988a8dabf2SAlan Cox * @ld: ldisc we are trying to fail back to 4998a8dabf2SAlan Cox * 5008a8dabf2SAlan Cox * Helper to try and recover a tty when switching back to the old 5018a8dabf2SAlan Cox * ldisc fails and we need something attached. 5028a8dabf2SAlan Cox */ 5038a8dabf2SAlan Cox 5048a8dabf2SAlan Cox static int tty_ldisc_failto(struct tty_struct *tty, int ld) 5058a8dabf2SAlan Cox { 5068a8dabf2SAlan Cox struct tty_ldisc *disc = tty_ldisc_get(tty, ld); 5078a8dabf2SAlan Cox int r; 5088a8dabf2SAlan Cox 5098a8dabf2SAlan Cox if (IS_ERR(disc)) 5108a8dabf2SAlan Cox return PTR_ERR(disc); 5118a8dabf2SAlan Cox tty->ldisc = disc; 5128a8dabf2SAlan Cox tty_set_termios_ldisc(tty, ld); 5138a8dabf2SAlan Cox if ((r = tty_ldisc_open(tty, disc)) < 0) 5148a8dabf2SAlan Cox tty_ldisc_put(disc); 5158a8dabf2SAlan Cox return r; 5168a8dabf2SAlan Cox } 5178a8dabf2SAlan Cox 5188a8dabf2SAlan Cox /** 519a8983d01SGreg Kroah-Hartman * tty_ldisc_restore - helper for tty ldisc change 520a8983d01SGreg Kroah-Hartman * @tty: tty to recover 521a8983d01SGreg Kroah-Hartman * @old: previous ldisc 522a8983d01SGreg Kroah-Hartman * 523a8983d01SGreg Kroah-Hartman * Restore the previous line discipline or N_TTY when a line discipline 524a8983d01SGreg Kroah-Hartman * change fails due to an open error 525a8983d01SGreg Kroah-Hartman */ 526a8983d01SGreg Kroah-Hartman 527a8983d01SGreg Kroah-Hartman static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) 528a8983d01SGreg Kroah-Hartman { 529a8983d01SGreg Kroah-Hartman /* There is an outstanding reference here so this is safe */ 530a8983d01SGreg Kroah-Hartman old = tty_ldisc_get(tty, old->ops->num); 531a8983d01SGreg Kroah-Hartman WARN_ON(IS_ERR(old)); 532a8983d01SGreg Kroah-Hartman tty->ldisc = old; 533a8983d01SGreg Kroah-Hartman tty_set_termios_ldisc(tty, old->ops->num); 534a8983d01SGreg Kroah-Hartman if (tty_ldisc_open(tty, old) < 0) { 535a8983d01SGreg Kroah-Hartman tty_ldisc_put(old); 5368a8dabf2SAlan Cox /* The traditional behaviour is to fall back to N_TTY, we 5378a8dabf2SAlan Cox want to avoid falling back to N_NULL unless we have no 5388a8dabf2SAlan Cox choice to avoid the risk of breaking anything */ 5398a8dabf2SAlan Cox if (tty_ldisc_failto(tty, N_TTY) < 0 && 5408a8dabf2SAlan Cox tty_ldisc_failto(tty, N_NULL) < 0) 5418a8dabf2SAlan Cox panic("Couldn't open N_NULL ldisc for %s.", 5428a8dabf2SAlan Cox tty_name(tty)); 543a8983d01SGreg Kroah-Hartman } 544a8983d01SGreg Kroah-Hartman } 545a8983d01SGreg Kroah-Hartman 546a8983d01SGreg Kroah-Hartman /** 54796fd7ce5SGreg Kroah-Hartman * tty_set_ldisc - set line discipline 54896fd7ce5SGreg Kroah-Hartman * @tty: the terminal to set 54996fd7ce5SGreg Kroah-Hartman * @ldisc: the line discipline 55096fd7ce5SGreg Kroah-Hartman * 55196fd7ce5SGreg Kroah-Hartman * Set the discipline of a tty line. Must be called from a process 55296fd7ce5SGreg Kroah-Hartman * context. The ldisc change logic has to protect itself against any 55396fd7ce5SGreg Kroah-Hartman * overlapping ldisc change (including on the other end of pty pairs), 55496fd7ce5SGreg Kroah-Hartman * the close of one side of a tty/pty pair, and eventually hangup. 55596fd7ce5SGreg Kroah-Hartman */ 55696fd7ce5SGreg Kroah-Hartman 557c12da96fSPeter Hurley int tty_set_ldisc(struct tty_struct *tty, int disc) 55896fd7ce5SGreg Kroah-Hartman { 559a8983d01SGreg Kroah-Hartman int retval; 560a8983d01SGreg Kroah-Hartman struct tty_ldisc *old_ldisc, *new_ldisc; 561a8983d01SGreg Kroah-Hartman 562a8983d01SGreg Kroah-Hartman new_ldisc = tty_ldisc_get(tty, disc); 563a8983d01SGreg Kroah-Hartman if (IS_ERR(new_ldisc)) 564a8983d01SGreg Kroah-Hartman return PTR_ERR(new_ldisc); 56596fd7ce5SGreg Kroah-Hartman 566c8483bc9SPeter Hurley tty_lock(tty); 567276a661aSPeter Hurley retval = tty_ldisc_lock(tty, 5 * HZ); 56863d8cb3fSPeter Hurley if (retval) 56963d8cb3fSPeter Hurley goto err; 57096fd7ce5SGreg Kroah-Hartman 571a570a49aSPeter Hurley if (!tty->ldisc) { 572a570a49aSPeter Hurley retval = -EIO; 573a570a49aSPeter Hurley goto out; 574a570a49aSPeter Hurley } 575a570a49aSPeter Hurley 57663d8cb3fSPeter Hurley /* Check the no-op case */ 577a8983d01SGreg Kroah-Hartman if (tty->ldisc->ops->num == disc) 57863d8cb3fSPeter Hurley goto out; 57996fd7ce5SGreg Kroah-Hartman 58063d8cb3fSPeter Hurley if (test_bit(TTY_HUPPED, &tty->flags)) { 58163d8cb3fSPeter Hurley /* We were raced by hangup */ 58263d8cb3fSPeter Hurley retval = -EIO; 58363d8cb3fSPeter Hurley goto out; 58496fd7ce5SGreg Kroah-Hartman } 58596fd7ce5SGreg Kroah-Hartman 586a8983d01SGreg Kroah-Hartman old_ldisc = tty->ldisc; 587a8983d01SGreg Kroah-Hartman 588a8983d01SGreg Kroah-Hartman /* Shutdown the old discipline. */ 589a8983d01SGreg Kroah-Hartman tty_ldisc_close(tty, old_ldisc); 590a8983d01SGreg Kroah-Hartman 591a8983d01SGreg Kroah-Hartman /* Now set up the new line discipline. */ 592a8983d01SGreg Kroah-Hartman tty->ldisc = new_ldisc; 593a8983d01SGreg Kroah-Hartman tty_set_termios_ldisc(tty, disc); 594a8983d01SGreg Kroah-Hartman 595a8983d01SGreg Kroah-Hartman retval = tty_ldisc_open(tty, new_ldisc); 59696fd7ce5SGreg Kroah-Hartman if (retval < 0) { 59796fd7ce5SGreg Kroah-Hartman /* Back to the old one or N_TTY if we can't */ 598a8983d01SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); 599a8983d01SGreg Kroah-Hartman tty_ldisc_restore(tty, old_ldisc); 60096fd7ce5SGreg Kroah-Hartman } 60196fd7ce5SGreg Kroah-Hartman 602a8983d01SGreg Kroah-Hartman if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) { 6039191aaaaSPeter Hurley down_read(&tty->termios_rwsem); 60496fd7ce5SGreg Kroah-Hartman tty->ops->set_ldisc(tty); 6059191aaaaSPeter Hurley up_read(&tty->termios_rwsem); 6069191aaaaSPeter Hurley } 60796fd7ce5SGreg Kroah-Hartman 608a8983d01SGreg Kroah-Hartman /* At this point we hold a reference to the new ldisc and a 609a8983d01SGreg Kroah-Hartman reference to the old ldisc, or we hold two references to 610a8983d01SGreg Kroah-Hartman the old ldisc (if it was restored as part of error cleanup 611a8983d01SGreg Kroah-Hartman above). In either case, releasing a single reference from 612a8983d01SGreg Kroah-Hartman the old ldisc is correct. */ 613a8983d01SGreg Kroah-Hartman new_ldisc = old_ldisc; 61463d8cb3fSPeter Hurley out: 615276a661aSPeter Hurley tty_ldisc_unlock(tty); 61696fd7ce5SGreg Kroah-Hartman 61796fd7ce5SGreg Kroah-Hartman /* Restart the work queue in case no characters kick it off. Safe if 61896fd7ce5SGreg Kroah-Hartman already running */ 61917a69219SPeter Hurley tty_buffer_restart_work(tty->port); 62063d8cb3fSPeter Hurley err: 621a8983d01SGreg Kroah-Hartman tty_ldisc_put(new_ldisc); /* drop the extra reference */ 62289c8d91eSAlan Cox tty_unlock(tty); 62396fd7ce5SGreg Kroah-Hartman return retval; 62496fd7ce5SGreg Kroah-Hartman } 6251ab92da3SOkash Khawaja EXPORT_SYMBOL_GPL(tty_set_ldisc); 62696fd7ce5SGreg Kroah-Hartman 62796fd7ce5SGreg Kroah-Hartman /** 6286ffeb4b2SPeter Hurley * tty_ldisc_kill - teardown ldisc 6296ffeb4b2SPeter Hurley * @tty: tty being released 6306ffeb4b2SPeter Hurley * 6316ffeb4b2SPeter Hurley * Perform final close of the ldisc and reset tty->ldisc 6326ffeb4b2SPeter Hurley */ 6336ffeb4b2SPeter Hurley static void tty_ldisc_kill(struct tty_struct *tty) 6346ffeb4b2SPeter Hurley { 6356ffeb4b2SPeter Hurley if (!tty->ldisc) 6366ffeb4b2SPeter Hurley return; 6376ffeb4b2SPeter Hurley /* 6386ffeb4b2SPeter Hurley * Now kill off the ldisc 6396ffeb4b2SPeter Hurley */ 6406ffeb4b2SPeter Hurley tty_ldisc_close(tty, tty->ldisc); 6416ffeb4b2SPeter Hurley tty_ldisc_put(tty->ldisc); 6426ffeb4b2SPeter Hurley /* Force an oops if we mess this up */ 6436ffeb4b2SPeter Hurley tty->ldisc = NULL; 6446ffeb4b2SPeter Hurley } 6456ffeb4b2SPeter Hurley 6466ffeb4b2SPeter Hurley /** 64796fd7ce5SGreg Kroah-Hartman * tty_reset_termios - reset terminal state 64896fd7ce5SGreg Kroah-Hartman * @tty: tty to reset 64996fd7ce5SGreg Kroah-Hartman * 65096fd7ce5SGreg Kroah-Hartman * Restore a terminal to the driver default state. 65196fd7ce5SGreg Kroah-Hartman */ 65296fd7ce5SGreg Kroah-Hartman 65396fd7ce5SGreg Kroah-Hartman static void tty_reset_termios(struct tty_struct *tty) 65496fd7ce5SGreg Kroah-Hartman { 6556a1c0680SPeter Hurley down_write(&tty->termios_rwsem); 656adc8d746SAlan Cox tty->termios = tty->driver->init_termios; 657adc8d746SAlan Cox tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); 658adc8d746SAlan Cox tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); 6596a1c0680SPeter Hurley up_write(&tty->termios_rwsem); 66096fd7ce5SGreg Kroah-Hartman } 66196fd7ce5SGreg Kroah-Hartman 66296fd7ce5SGreg Kroah-Hartman 66396fd7ce5SGreg Kroah-Hartman /** 66496fd7ce5SGreg Kroah-Hartman * tty_ldisc_reinit - reinitialise the tty ldisc 66596fd7ce5SGreg Kroah-Hartman * @tty: tty to reinit 666c12da96fSPeter Hurley * @disc: line discipline to reinitialize 66796fd7ce5SGreg Kroah-Hartman * 6687896f30dSPeter Hurley * Completely reinitialize the line discipline state, by closing the 669892d1fa7SPeter Hurley * current instance, if there is one, and opening a new instance. If 670892d1fa7SPeter Hurley * an error occurs opening the new non-N_TTY instance, the instance 671892d1fa7SPeter Hurley * is dropped and tty->ldisc reset to NULL. The caller can then retry 672892d1fa7SPeter Hurley * with N_TTY instead. 6737896f30dSPeter Hurley * 6747896f30dSPeter Hurley * Returns 0 if successful, otherwise error code < 0 67596fd7ce5SGreg Kroah-Hartman */ 67696fd7ce5SGreg Kroah-Hartman 677892d1fa7SPeter Hurley int tty_ldisc_reinit(struct tty_struct *tty, int disc) 67896fd7ce5SGreg Kroah-Hartman { 6797896f30dSPeter Hurley struct tty_ldisc *ld; 6807896f30dSPeter Hurley int retval; 6811c95ba1eSPhilippe Rétornaz 6827896f30dSPeter Hurley ld = tty_ldisc_get(tty, disc); 683a8983d01SGreg Kroah-Hartman if (IS_ERR(ld)) { 684a8983d01SGreg Kroah-Hartman BUG_ON(disc == N_TTY); 6857896f30dSPeter Hurley return PTR_ERR(ld); 686a8983d01SGreg Kroah-Hartman } 68796fd7ce5SGreg Kroah-Hartman 6887896f30dSPeter Hurley if (tty->ldisc) { 68996fd7ce5SGreg Kroah-Hartman tty_ldisc_close(tty, tty->ldisc); 69096fd7ce5SGreg Kroah-Hartman tty_ldisc_put(tty->ldisc); 6917896f30dSPeter Hurley } 6927896f30dSPeter Hurley 6937896f30dSPeter Hurley /* switch the line discipline */ 694f4807045SPeter Hurley tty->ldisc = ld; 695c12da96fSPeter Hurley tty_set_termios_ldisc(tty, disc); 6967896f30dSPeter Hurley retval = tty_ldisc_open(tty, tty->ldisc); 6977896f30dSPeter Hurley if (retval) { 6987896f30dSPeter Hurley tty_ldisc_put(tty->ldisc); 6997896f30dSPeter Hurley tty->ldisc = NULL; 7007896f30dSPeter Hurley } 7017896f30dSPeter Hurley return retval; 70296fd7ce5SGreg Kroah-Hartman } 70396fd7ce5SGreg Kroah-Hartman 70496fd7ce5SGreg Kroah-Hartman /** 70596fd7ce5SGreg Kroah-Hartman * tty_ldisc_hangup - hangup ldisc reset 70696fd7ce5SGreg Kroah-Hartman * @tty: tty being hung up 70796fd7ce5SGreg Kroah-Hartman * 70896fd7ce5SGreg Kroah-Hartman * Some tty devices reset their termios when they receive a hangup 70996fd7ce5SGreg Kroah-Hartman * event. In that situation we must also switch back to N_TTY properly 71096fd7ce5SGreg Kroah-Hartman * before we reset the termios data. 71196fd7ce5SGreg Kroah-Hartman * 71296fd7ce5SGreg Kroah-Hartman * Locking: We can take the ldisc mutex as the rest of the code is 71396fd7ce5SGreg Kroah-Hartman * careful to allow for this. 71496fd7ce5SGreg Kroah-Hartman * 71596fd7ce5SGreg Kroah-Hartman * In the pty pair case this occurs in the close() path of the 71696fd7ce5SGreg Kroah-Hartman * tty itself so we must be careful about locking rules. 71796fd7ce5SGreg Kroah-Hartman */ 71896fd7ce5SGreg Kroah-Hartman 719892d1fa7SPeter Hurley void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) 72096fd7ce5SGreg Kroah-Hartman { 72196fd7ce5SGreg Kroah-Hartman struct tty_ldisc *ld; 72296fd7ce5SGreg Kroah-Hartman 723a570a49aSPeter Hurley tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc); 724fc575ee6SPeter Hurley 72596fd7ce5SGreg Kroah-Hartman ld = tty_ldisc_ref(tty); 72696fd7ce5SGreg Kroah-Hartman if (ld != NULL) { 72796fd7ce5SGreg Kroah-Hartman if (ld->ops->flush_buffer) 72896fd7ce5SGreg Kroah-Hartman ld->ops->flush_buffer(tty); 72996fd7ce5SGreg Kroah-Hartman tty_driver_flush_buffer(tty); 73096fd7ce5SGreg Kroah-Hartman if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && 73196fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup) 73296fd7ce5SGreg Kroah-Hartman ld->ops->write_wakeup(tty); 73396fd7ce5SGreg Kroah-Hartman if (ld->ops->hangup) 73496fd7ce5SGreg Kroah-Hartman ld->ops->hangup(tty); 73596fd7ce5SGreg Kroah-Hartman tty_ldisc_deref(ld); 73696fd7ce5SGreg Kroah-Hartman } 73736697529SPeter Hurley 73896fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->write_wait, POLLOUT); 73996fd7ce5SGreg Kroah-Hartman wake_up_interruptible_poll(&tty->read_wait, POLLIN); 74036697529SPeter Hurley 74196fd7ce5SGreg Kroah-Hartman /* 74296fd7ce5SGreg Kroah-Hartman * Shutdown the current line discipline, and reset it to 74396fd7ce5SGreg Kroah-Hartman * N_TTY if need be. 74496fd7ce5SGreg Kroah-Hartman * 74596fd7ce5SGreg Kroah-Hartman * Avoid racing set_ldisc or tty_ldisc_release 74696fd7ce5SGreg Kroah-Hartman */ 747fae76e9aSPeter Hurley tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); 74896fd7ce5SGreg Kroah-Hartman 749892d1fa7SPeter Hurley if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) 75096fd7ce5SGreg Kroah-Hartman tty_reset_termios(tty); 751fc575ee6SPeter Hurley 752892d1fa7SPeter Hurley if (tty->ldisc) { 753892d1fa7SPeter Hurley if (reinit) { 754e65c62b1SJohannes Weiner if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0 && 755e65c62b1SJohannes Weiner tty_ldisc_reinit(tty, N_TTY) < 0) 756e65c62b1SJohannes Weiner WARN_ON(tty_ldisc_reinit(tty, N_NULL) < 0); 757892d1fa7SPeter Hurley } else 758892d1fa7SPeter Hurley tty_ldisc_kill(tty); 759892d1fa7SPeter Hurley } 760892d1fa7SPeter Hurley tty_ldisc_unlock(tty); 76196fd7ce5SGreg Kroah-Hartman } 76296fd7ce5SGreg Kroah-Hartman 76396fd7ce5SGreg Kroah-Hartman /** 76496fd7ce5SGreg Kroah-Hartman * tty_ldisc_setup - open line discipline 76596fd7ce5SGreg Kroah-Hartman * @tty: tty being shut down 76696fd7ce5SGreg Kroah-Hartman * @o_tty: pair tty for pty/tty pairs 76796fd7ce5SGreg Kroah-Hartman * 76896fd7ce5SGreg Kroah-Hartman * Called during the initial open of a tty/pty pair in order to set up the 76996fd7ce5SGreg Kroah-Hartman * line disciplines and bind them to the tty. This has no locking issues 77096fd7ce5SGreg Kroah-Hartman * as the device isn't yet active. 77196fd7ce5SGreg Kroah-Hartman */ 77296fd7ce5SGreg Kroah-Hartman 77396fd7ce5SGreg Kroah-Hartman int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) 77496fd7ce5SGreg Kroah-Hartman { 7759de2a7ceSPeter Hurley int retval = tty_ldisc_open(tty, tty->ldisc); 77696fd7ce5SGreg Kroah-Hartman if (retval) 77796fd7ce5SGreg Kroah-Hartman return retval; 77896fd7ce5SGreg Kroah-Hartman 77996fd7ce5SGreg Kroah-Hartman if (o_tty) { 78096fd7ce5SGreg Kroah-Hartman retval = tty_ldisc_open(o_tty, o_tty->ldisc); 78196fd7ce5SGreg Kroah-Hartman if (retval) { 7829de2a7ceSPeter Hurley tty_ldisc_close(tty, tty->ldisc); 78396fd7ce5SGreg Kroah-Hartman return retval; 78496fd7ce5SGreg Kroah-Hartman } 78596fd7ce5SGreg Kroah-Hartman } 78696fd7ce5SGreg Kroah-Hartman return 0; 78796fd7ce5SGreg Kroah-Hartman } 78889c8d91eSAlan Cox 78996fd7ce5SGreg Kroah-Hartman /** 79096fd7ce5SGreg Kroah-Hartman * tty_ldisc_release - release line discipline 79162462aefSPeter Hurley * @tty: tty being shut down (or one end of pty pair) 79296fd7ce5SGreg Kroah-Hartman * 79362462aefSPeter Hurley * Called during the final close of a tty or a pty pair in order to shut 7945b6e6832SPeter Hurley * down the line discpline layer. On exit, each tty's ldisc is NULL. 79596fd7ce5SGreg Kroah-Hartman */ 79696fd7ce5SGreg Kroah-Hartman 79762462aefSPeter Hurley void tty_ldisc_release(struct tty_struct *tty) 79896fd7ce5SGreg Kroah-Hartman { 79962462aefSPeter Hurley struct tty_struct *o_tty = tty->link; 80062462aefSPeter Hurley 80196fd7ce5SGreg Kroah-Hartman /* 802a2965b7bSPeter Hurley * Shutdown this line discipline. As this is the final close, 803a2965b7bSPeter Hurley * it does not race with the set_ldisc code path. 80496fd7ce5SGreg Kroah-Hartman */ 80596fd7ce5SGreg Kroah-Hartman 80636697529SPeter Hurley tty_ldisc_lock_pair(tty, o_tty); 80789c8d91eSAlan Cox tty_ldisc_kill(tty); 80889c8d91eSAlan Cox if (o_tty) 80989c8d91eSAlan Cox tty_ldisc_kill(o_tty); 81036697529SPeter Hurley tty_ldisc_unlock_pair(tty, o_tty); 81136697529SPeter Hurley 81296fd7ce5SGreg Kroah-Hartman /* And the memory resources remaining (buffers, termios) will be 81396fd7ce5SGreg Kroah-Hartman disposed of when the kref hits zero */ 814fc575ee6SPeter Hurley 815fb6edc91SPeter Hurley tty_ldisc_debug(tty, "released\n"); 81696fd7ce5SGreg Kroah-Hartman } 8171ab92da3SOkash Khawaja EXPORT_SYMBOL_GPL(tty_ldisc_release); 81896fd7ce5SGreg Kroah-Hartman 81996fd7ce5SGreg Kroah-Hartman /** 82096fd7ce5SGreg Kroah-Hartman * tty_ldisc_init - ldisc setup for new tty 82196fd7ce5SGreg Kroah-Hartman * @tty: tty being allocated 82296fd7ce5SGreg Kroah-Hartman * 82396fd7ce5SGreg Kroah-Hartman * Set up the line discipline objects for a newly allocated tty. Note that 82496fd7ce5SGreg Kroah-Hartman * the tty structure is not completely set up when this call is made. 82596fd7ce5SGreg Kroah-Hartman */ 82696fd7ce5SGreg Kroah-Hartman 82796fd7ce5SGreg Kroah-Hartman void tty_ldisc_init(struct tty_struct *tty) 82896fd7ce5SGreg Kroah-Hartman { 82936697529SPeter Hurley struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); 83096fd7ce5SGreg Kroah-Hartman if (IS_ERR(ld)) 83196fd7ce5SGreg Kroah-Hartman panic("n_tty: init_tty"); 832f4807045SPeter Hurley tty->ldisc = ld; 83396fd7ce5SGreg Kroah-Hartman } 83496fd7ce5SGreg Kroah-Hartman 8356716671dSJiri Slaby /** 836c8b710b3SPeter Hurley * tty_ldisc_deinit - ldisc cleanup for new tty 8376716671dSJiri Slaby * @tty: tty that was allocated recently 8386716671dSJiri Slaby * 8396716671dSJiri Slaby * The tty structure must not becompletely set up (tty_ldisc_setup) when 8406716671dSJiri Slaby * this call is made. 8416716671dSJiri Slaby */ 8426716671dSJiri Slaby void tty_ldisc_deinit(struct tty_struct *tty) 8436716671dSJiri Slaby { 844c8b710b3SPeter Hurley if (tty->ldisc) 845ebc9baedSPeter Hurley tty_ldisc_put(tty->ldisc); 846f4807045SPeter Hurley tty->ldisc = NULL; 8476716671dSJiri Slaby } 848