^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) #include <linux/types.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) #include <linux/errno.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) #include <linux/kmod.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) #include <linux/interrupt.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) #include <linux/tty.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <linux/tty_driver.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <linux/file.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/string.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/slab.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/poll.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/proc_fs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <linux/device.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <linux/wait.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <linux/bitops.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include <linux/seq_file.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) #include <linux/uaccess.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) #include <linux/ratelimit.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) #undef LDISC_DEBUG_HANGUP
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) #ifdef LDISC_DEBUG_HANGUP
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) #define tty_ldisc_debug(tty, f, args...)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) /* lockdep nested classes for tty->ldisc_sem */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) enum {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) LDISC_SEM_NORMAL,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) LDISC_SEM_OTHER,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * This guards the refcounted line discipline lists. The lock
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) * must be taken with irqs off because there are hangup path
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * callers who will do ldisc lookups and cannot sleep.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) /* Line disc dispatch table */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * tty_register_ldisc - install a line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * @disc: ldisc number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) * @new_ldisc: pointer to the ldisc object
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) * Installs a new line discipline into the kernel. The discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * is set up as unreferenced and then made available to the kernel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) * from this point onwards.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) * Locking:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) * takes tty_ldiscs_lock to guard against ldisc races
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) int ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) if (disc < N_TTY || disc >= NR_LDISCS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) tty_ldiscs[disc] = new_ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) new_ldisc->num = disc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) new_ldisc->refcount = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) EXPORT_SYMBOL(tty_register_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) * tty_unregister_ldisc - unload a line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) * @disc: ldisc number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) * Remove a line discipline from the kernel providing it is not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) * currently in use.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) * Locking:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) * takes tty_ldiscs_lock to guard against ldisc races
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) int tty_unregister_ldisc(int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) int ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) if (disc < N_TTY || disc >= NR_LDISCS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) if (tty_ldiscs[disc]->refcount)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) ret = -EBUSY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) tty_ldiscs[disc] = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) EXPORT_SYMBOL(tty_unregister_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) static struct tty_ldisc_ops *get_ldops(int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) struct tty_ldisc_ops *ldops, *ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) ret = ERR_PTR(-EINVAL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) ldops = tty_ldiscs[disc];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) if (ldops) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) ret = ERR_PTR(-EAGAIN);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) if (try_module_get(ldops->owner)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) ldops->refcount++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) ret = ldops;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) static void put_ldops(struct tty_ldisc_ops *ldops)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) ldops->refcount--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) module_put(ldops->owner);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) * tty_ldisc_get - take a reference to an ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) * @disc: ldisc number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) * Takes a reference to a line discipline. Deals with refcounts and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) * module locking counts.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * if the discipline is not registered
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * -EAGAIN if request_module() failed to load or register the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * the discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) * -ENOMEM if allocation failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * Otherwise, returns a pointer to the discipline and bumps the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) * ref count
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) * Locking:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) * takes tty_ldiscs_lock to guard against ldisc races
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) static int tty_ldisc_autoload = IS_BUILTIN(CONFIG_LDISC_AUTOLOAD);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) struct tty_ldisc *ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) struct tty_ldisc_ops *ldops;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) if (disc < N_TTY || disc >= NR_LDISCS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) return ERR_PTR(-EINVAL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) * Get the ldisc ops - we may need to request them to be loaded
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) * dynamically and try again.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) ldops = get_ldops(disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) if (IS_ERR(ldops)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) return ERR_PTR(-EPERM);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) request_module("tty-ldisc-%d", disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) ldops = get_ldops(disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) if (IS_ERR(ldops))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) return ERR_CAST(ldops);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) * There is no way to handle allocation failure of only 16 bytes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) * Let's simplify error handling and save more memory.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) ld->ops = ldops;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) ld->tty = tty;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) return ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) * tty_ldisc_put - release the ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) * Complement of tty_ldisc_get().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) static void tty_ldisc_put(struct tty_ldisc *ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) if (WARN_ON_ONCE(!ld))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) put_ldops(ld->ops);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) kfree(ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) return (*pos < NR_LDISCS) ? pos : NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) (*pos)++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) return (*pos < NR_LDISCS) ? pos : NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) static void tty_ldiscs_seq_stop(struct seq_file *m, void *v)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) static int tty_ldiscs_seq_show(struct seq_file *m, void *v)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) int i = *(loff_t *)v;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) struct tty_ldisc_ops *ldops;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) ldops = get_ldops(i);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) if (IS_ERR(ldops))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) put_ldops(ldops);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) const struct seq_operations tty_ldiscs_seq_ops = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) .start = tty_ldiscs_seq_start,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) .next = tty_ldiscs_seq_next,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) .stop = tty_ldiscs_seq_stop,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) .show = tty_ldiscs_seq_show,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) * tty_ldisc_ref_wait - wait for the tty ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) * @tty: tty device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) * Dereference the line discipline for the terminal and take a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) * reference to it. If the line discipline is in flux then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) * wait patiently until it changes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) * Returns: NULL if the tty has been hungup and not re-opened with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) * a new file descriptor, otherwise valid ldisc reference
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) * Note: Must not be called from an IRQ/timer context. The caller
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) * must also be careful not to hold other locks that will deadlock
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) * against a discipline change, such as an existing ldisc reference
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) * (which we check for)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) * Note: a file_operations routine (read/poll/write) should use this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) * function to wait for any ldisc lifetime events to finish.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) struct tty_ldisc *ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) ld = tty->ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) if (!ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) ldsem_up_read(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) return ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) * tty_ldisc_ref - get the tty ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) * @tty: tty device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) * Dereference the line discipline for the terminal and take a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) * reference to it. If the line discipline is in flux then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) * return NULL. Can be called from IRQ and timer functions.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) struct tty_ldisc *ld = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) if (ldsem_down_read_trylock(&tty->ldisc_sem)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) ld = tty->ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) if (!ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) ldsem_up_read(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) return ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) EXPORT_SYMBOL_GPL(tty_ldisc_ref);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) * tty_ldisc_deref - free a tty ldisc reference
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) * @ld: reference to free up
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) * be called in IRQ context.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) void tty_ldisc_deref(struct tty_ldisc *ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) ldsem_up_read(&ld->tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) EXPORT_SYMBOL_GPL(tty_ldisc_deref);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) static inline int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) return ldsem_down_write(&tty->ldisc_sem, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) static inline int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) return ldsem_down_write_nested(&tty->ldisc_sem,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) LDISC_SEM_OTHER, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) static inline void __tty_ldisc_unlock(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) ldsem_up_write(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) /* Kindly asking blocked readers to release the read side */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) set_bit(TTY_LDISC_CHANGING, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) wake_up_interruptible_all(&tty->read_wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) wake_up_interruptible_all(&tty->write_wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) ret = __tty_ldisc_lock(tty, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) if (!ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) return -EBUSY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) set_bit(TTY_LDISC_HALTED, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) void tty_ldisc_unlock(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) clear_bit(TTY_LDISC_HALTED, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) /* Can be cleared here - ldisc_unlock will wake up writers firstly */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) clear_bit(TTY_LDISC_CHANGING, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) __tty_ldisc_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) unsigned long timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) if (tty < tty2) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) ret = __tty_ldisc_lock(tty, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) if (ret) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) ret = __tty_ldisc_lock_nested(tty2, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) if (!ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) __tty_ldisc_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) /* if this is possible, it has lots of implications */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) WARN_ON_ONCE(tty == tty2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) if (tty2 && tty != tty2) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) ret = __tty_ldisc_lock(tty2, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) if (ret) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) ret = __tty_ldisc_lock_nested(tty, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) if (!ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) __tty_ldisc_unlock(tty2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) } else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) ret = __tty_ldisc_lock(tty, timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) if (!ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) return -EBUSY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) set_bit(TTY_LDISC_HALTED, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) if (tty2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) set_bit(TTY_LDISC_HALTED, &tty2->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) static void tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) static void tty_ldisc_unlock_pair(struct tty_struct *tty,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) struct tty_struct *tty2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) __tty_ldisc_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) if (tty2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) __tty_ldisc_unlock(tty2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) * tty_ldisc_flush - flush line discipline queue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) * @tty: tty
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) * Flush the line discipline queue (if any) and the tty flip buffers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) * for this tty.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) void tty_ldisc_flush(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) struct tty_ldisc *ld = tty_ldisc_ref(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) tty_buffer_flush(tty, ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) if (ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) tty_ldisc_deref(ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) EXPORT_SYMBOL_GPL(tty_ldisc_flush);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) * tty_set_termios_ldisc - set ldisc field
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) * @tty: tty structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) * @disc: line discipline number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) * This is probably overkill for real world processors but
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) * they are not on hot paths so a little discipline won't do
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427) * any harm.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429) * The line discipline-related tty_struct fields are reset to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) * prevent the ldisc driver from re-using stale information for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431) * the new ldisc instance.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433) * Locking: takes termios_rwsem
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436) static void tty_set_termios_ldisc(struct tty_struct *tty, int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438) down_write(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439) tty->termios.c_line = disc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) up_write(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) tty->disc_data = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) tty->receive_room = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) * tty_ldisc_open - open a line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) * @tty: tty we are opening the ldisc on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) * @ld: discipline to open
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) * A helper opening method. Also a convenient debugging and check
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) * point.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) * Locking: always called with BTM already held.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) if (ld->ops->open) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462) /* BTM here locks versus a hangup event */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) ret = ld->ops->open(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465) clear_bit(TTY_LDISC_OPEN, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) tty_ldisc_debug(tty, "%p: opened\n", ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) * tty_ldisc_close - close a line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475) * @tty: tty we are opening the ldisc on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) * @ld: discipline to close
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478) * A helper close method. Also a convenient debugging and check
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) * point.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482) static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 483) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 484) lockdep_assert_held_write(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 485) WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 486) clear_bit(TTY_LDISC_OPEN, &tty->flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 487) if (ld->ops->close)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 488) ld->ops->close(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 489) tty_ldisc_debug(tty, "%p: closed\n", ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 490) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 491)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 492) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 493) * tty_ldisc_failto - helper for ldisc failback
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 494) * @tty: tty to open the ldisc on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 495) * @ld: ldisc we are trying to fail back to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 496) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 497) * Helper to try and recover a tty when switching back to the old
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 498) * ldisc fails and we need something attached.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 499) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 500)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 501) static int tty_ldisc_failto(struct tty_struct *tty, int ld)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 502) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 503) struct tty_ldisc *disc = tty_ldisc_get(tty, ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 504) int r;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 505)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 506) lockdep_assert_held_write(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 507) if (IS_ERR(disc))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 508) return PTR_ERR(disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 509) tty->ldisc = disc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 510) tty_set_termios_ldisc(tty, ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 511) if ((r = tty_ldisc_open(tty, disc)) < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 512) tty_ldisc_put(disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 513) return r;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 514) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 515)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 516) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 517) * tty_ldisc_restore - helper for tty ldisc change
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 518) * @tty: tty to recover
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 519) * @old: previous ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 520) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 521) * Restore the previous line discipline or N_TTY when a line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 522) * change fails due to an open error
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 523) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 524)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 525) static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 526) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 527) /* There is an outstanding reference here so this is safe */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 528) if (tty_ldisc_failto(tty, old->ops->num) < 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 529) const char *name = tty_name(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 530)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 531) pr_warn("Falling back ldisc for %s.\n", name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 532) /* The traditional behaviour is to fall back to N_TTY, we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 533) want to avoid falling back to N_NULL unless we have no
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 534) choice to avoid the risk of breaking anything */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 535) if (tty_ldisc_failto(tty, N_TTY) < 0 &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 536) tty_ldisc_failto(tty, N_NULL) < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 537) panic("Couldn't open N_NULL ldisc for %s.", name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 538) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 539) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 540)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 541) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 542) * tty_set_ldisc - set line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 543) * @tty: the terminal to set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 544) * @disc: the line discipline number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 545) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 546) * Set the discipline of a tty line. Must be called from a process
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 547) * context. The ldisc change logic has to protect itself against any
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 548) * overlapping ldisc change (including on the other end of pty pairs),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 549) * the close of one side of a tty/pty pair, and eventually hangup.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 550) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 551)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 552) int tty_set_ldisc(struct tty_struct *tty, int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 553) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 554) int retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 555) struct tty_ldisc *old_ldisc, *new_ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 556)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 557) new_ldisc = tty_ldisc_get(tty, disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 558) if (IS_ERR(new_ldisc))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 559) return PTR_ERR(new_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 560)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 561) tty_lock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 562) retval = tty_ldisc_lock(tty, 5 * HZ);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 563) if (retval)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 564) goto err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 565)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 566) if (!tty->ldisc) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 567) retval = -EIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 568) goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 569) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 570)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 571) /* Check the no-op case */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 572) if (tty->ldisc->ops->num == disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 573) goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 574)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 575) if (test_bit(TTY_HUPPED, &tty->flags)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 576) /* We were raced by hangup */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 577) retval = -EIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 578) goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 579) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 580)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 581) old_ldisc = tty->ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 582)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 583) /* Shutdown the old discipline. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 584) tty_ldisc_close(tty, old_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 585)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 586) /* Now set up the new line discipline. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 587) tty->ldisc = new_ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 588) tty_set_termios_ldisc(tty, disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 589)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 590) retval = tty_ldisc_open(tty, new_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 591) if (retval < 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 592) /* Back to the old one or N_TTY if we can't */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 593) tty_ldisc_put(new_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 594) tty_ldisc_restore(tty, old_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 595) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 596)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 597) if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 598) down_read(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 599) tty->ops->set_ldisc(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 600) up_read(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 601) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 602)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 603) /* At this point we hold a reference to the new ldisc and a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 604) reference to the old ldisc, or we hold two references to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 605) the old ldisc (if it was restored as part of error cleanup
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 606) above). In either case, releasing a single reference from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 607) the old ldisc is correct. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 608) new_ldisc = old_ldisc;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 609) out:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 610) tty_ldisc_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 611)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 612) /* Restart the work queue in case no characters kick it off. Safe if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 613) already running */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 614) tty_buffer_restart_work(tty->port);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 615) err:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 616) tty_ldisc_put(new_ldisc); /* drop the extra reference */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 617) tty_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 618) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 619) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 620) EXPORT_SYMBOL_GPL(tty_set_ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 621)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 622) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 623) * tty_ldisc_kill - teardown ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 624) * @tty: tty being released
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 625) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 626) * Perform final close of the ldisc and reset tty->ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 627) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 628) static void tty_ldisc_kill(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 629) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 630) lockdep_assert_held_write(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 631) if (!tty->ldisc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 632) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 633) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 634) * Now kill off the ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 635) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 636) tty_ldisc_close(tty, tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 637) tty_ldisc_put(tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 638) /* Force an oops if we mess this up */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 639) tty->ldisc = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 640) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 641)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 642) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 643) * tty_reset_termios - reset terminal state
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 644) * @tty: tty to reset
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 645) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 646) * Restore a terminal to the driver default state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 647) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 648)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 649) static void tty_reset_termios(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 650) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 651) down_write(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 652) tty->termios = tty->driver->init_termios;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 653) tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 654) tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 655) up_write(&tty->termios_rwsem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 656) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 657)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 658)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 659) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 660) * tty_ldisc_reinit - reinitialise the tty ldisc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 661) * @tty: tty to reinit
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 662) * @disc: line discipline to reinitialize
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 663) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 664) * Completely reinitialize the line discipline state, by closing the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 665) * current instance, if there is one, and opening a new instance. If
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 666) * an error occurs opening the new non-N_TTY instance, the instance
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 667) * is dropped and tty->ldisc reset to NULL. The caller can then retry
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 668) * with N_TTY instead.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 669) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 670) * Returns 0 if successful, otherwise error code < 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 671) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 672)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 673) int tty_ldisc_reinit(struct tty_struct *tty, int disc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 674) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 675) struct tty_ldisc *ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 676) int retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 677)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 678) lockdep_assert_held_write(&tty->ldisc_sem);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 679) ld = tty_ldisc_get(tty, disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 680) if (IS_ERR(ld)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 681) BUG_ON(disc == N_TTY);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 682) return PTR_ERR(ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 683) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 684)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 685) if (tty->ldisc) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 686) tty_ldisc_close(tty, tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 687) tty_ldisc_put(tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 688) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 689)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 690) /* switch the line discipline */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 691) tty->ldisc = ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 692) tty_set_termios_ldisc(tty, disc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 693) retval = tty_ldisc_open(tty, tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 694) if (retval) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 695) tty_ldisc_put(tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 696) tty->ldisc = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 697) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 698) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 699) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 700)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 701) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 702) * tty_ldisc_hangup - hangup ldisc reset
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 703) * @tty: tty being hung up
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 704) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 705) * Some tty devices reset their termios when they receive a hangup
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 706) * event. In that situation we must also switch back to N_TTY properly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 707) * before we reset the termios data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 708) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 709) * Locking: We can take the ldisc mutex as the rest of the code is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 710) * careful to allow for this.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 711) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 712) * In the pty pair case this occurs in the close() path of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 713) * tty itself so we must be careful about locking rules.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 714) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 715)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 716) void tty_ldisc_hangup(struct tty_struct *tty, bool reinit)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 717) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 718) struct tty_ldisc *ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 719)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 720) tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 721)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 722) ld = tty_ldisc_ref(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 723) if (ld != NULL) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 724) if (ld->ops->flush_buffer)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 725) ld->ops->flush_buffer(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 726) tty_driver_flush_buffer(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 727) if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 728) ld->ops->write_wakeup)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 729) ld->ops->write_wakeup(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 730) if (ld->ops->hangup)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 731) ld->ops->hangup(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 732) tty_ldisc_deref(ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 733) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 734)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 735) wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 736) wake_up_interruptible_poll(&tty->read_wait, EPOLLIN);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 737)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 738) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 739) * Shutdown the current line discipline, and reset it to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 740) * N_TTY if need be.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 741) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 742) * Avoid racing set_ldisc or tty_ldisc_release
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 743) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 744) tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 745)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 746) if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 747) tty_reset_termios(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 748)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 749) if (tty->ldisc) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 750) if (reinit) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 751) if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0 &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 752) tty_ldisc_reinit(tty, N_TTY) < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 753) WARN_ON(tty_ldisc_reinit(tty, N_NULL) < 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 754) } else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 755) tty_ldisc_kill(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 756) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 757) tty_ldisc_unlock(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 758) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 759)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 760) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 761) * tty_ldisc_setup - open line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 762) * @tty: tty being shut down
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 763) * @o_tty: pair tty for pty/tty pairs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 764) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 765) * Called during the initial open of a tty/pty pair in order to set up the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 766) * line disciplines and bind them to the tty. This has no locking issues
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 767) * as the device isn't yet active.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 768) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 769)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 770) int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 771) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 772) int retval = tty_ldisc_open(tty, tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 773) if (retval)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 774) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 775)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 776) if (o_tty) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 777) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 778) * Called without o_tty->ldisc_sem held, as o_tty has been
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 779) * just allocated and no one has a reference to it.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 780) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 781) retval = tty_ldisc_open(o_tty, o_tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 782) if (retval) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 783) tty_ldisc_close(tty, tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 784) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 785) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 786) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 787) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 788) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 789)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 790) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 791) * tty_ldisc_release - release line discipline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 792) * @tty: tty being shut down (or one end of pty pair)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 793) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 794) * Called during the final close of a tty or a pty pair in order to shut
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 795) * down the line discpline layer. On exit, each tty's ldisc is NULL.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 796) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 797)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 798) void tty_ldisc_release(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 799) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 800) struct tty_struct *o_tty = tty->link;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 801)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 802) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 803) * Shutdown this line discipline. As this is the final close,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 804) * it does not race with the set_ldisc code path.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 805) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 806)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 807) tty_ldisc_lock_pair(tty, o_tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 808) tty_ldisc_kill(tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 809) if (o_tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 810) tty_ldisc_kill(o_tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 811) tty_ldisc_unlock_pair(tty, o_tty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 812)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 813) /* And the memory resources remaining (buffers, termios) will be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 814) disposed of when the kref hits zero */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 815)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 816) tty_ldisc_debug(tty, "released\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 817) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 818) EXPORT_SYMBOL_GPL(tty_ldisc_release);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 819)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 820) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 821) * tty_ldisc_init - ldisc setup for new tty
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 822) * @tty: tty being allocated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 823) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 824) * Set up the line discipline objects for a newly allocated tty. Note that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 825) * the tty structure is not completely set up when this call is made.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 826) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 827)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 828) int tty_ldisc_init(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 829) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 830) struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 831) if (IS_ERR(ld))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 832) return PTR_ERR(ld);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 833) tty->ldisc = ld;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 834) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 835) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 836)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 837) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 838) * tty_ldisc_deinit - ldisc cleanup for new tty
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 839) * @tty: tty that was allocated recently
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 840) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 841) * The tty structure must not becompletely set up (tty_ldisc_setup) when
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 842) * this call is made.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 843) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 844) void tty_ldisc_deinit(struct tty_struct *tty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 845) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 846) /* no ldisc_sem, tty is being destroyed */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 847) if (tty->ldisc)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 848) tty_ldisc_put(tty->ldisc);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 849) tty->ldisc = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 850) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 851)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 852) static struct ctl_table tty_table[] = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 853) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 854) .procname = "ldisc_autoload",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 855) .data = &tty_ldisc_autoload,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 856) .maxlen = sizeof(tty_ldisc_autoload),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 857) .mode = 0644,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 858) .proc_handler = proc_dointvec,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 859) .extra1 = SYSCTL_ZERO,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 860) .extra2 = SYSCTL_ONE,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 861) },
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 862) { }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 863) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 864)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 865) static struct ctl_table tty_dir_table[] = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 866) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 867) .procname = "tty",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 868) .mode = 0555,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 869) .child = tty_table,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 870) },
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 871) { }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 872) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 873)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 874) static struct ctl_table tty_root_table[] = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 875) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 876) .procname = "dev",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 877) .mode = 0555,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 878) .child = tty_dir_table,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 879) },
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 880) { }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 881) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 882)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 883) void tty_sysctl_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 884) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 885) register_sysctl_table(tty_root_table);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 886) }
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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