| #include <linux/types.h> |
| #include <linux/errno.h> |
| #include <linux/kmod.h> |
| #include <linux/sched.h> |
| #include <linux/interrupt.h> |
| #include <linux/tty.h> |
| #include <linux/tty_driver.h> |
| #include <linux/file.h> |
| #include <linux/mm.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/poll.h> |
| #include <linux/proc_fs.h> |
| #include <linux/module.h> |
| #include <linux/device.h> |
| #include <linux/wait.h> |
| #include <linux/bitops.h> |
| #include <linux/seq_file.h> |
| #include <linux/uaccess.h> |
| #include <linux/ratelimit.h> |
| |
| #undef LDISC_DEBUG_HANGUP |
| |
| #ifdef LDISC_DEBUG_HANGUP |
| #define tty_ldisc_debug(tty, f, args...) tty_debug(tty, f, ##args) |
| #else |
| #define tty_ldisc_debug(tty, f, args...) |
| #endif |
| |
| /* lockdep nested classes for tty->ldisc_sem */ |
| enum { |
| LDISC_SEM_NORMAL, |
| LDISC_SEM_OTHER, |
| }; |
| |
| |
| /* |
| * This guards the refcounted line discipline lists. The lock |
| * must be taken with irqs off because there are hangup path |
| * callers who will do ldisc lookups and cannot sleep. |
| */ |
| |
| static DEFINE_RAW_SPINLOCK(tty_ldiscs_lock); |
| /* Line disc dispatch table */ |
| static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS]; |
| |
| /** |
| * tty_register_ldisc - install a line discipline |
| * @disc: ldisc number |
| * @new_ldisc: pointer to the ldisc object |
| * |
| * Installs a new line discipline into the kernel. The discipline |
| * is set up as unreferenced and then made available to the kernel |
| * from this point onwards. |
| * |
| * Locking: |
| * takes tty_ldiscs_lock to guard against ldisc races |
| */ |
| |
| int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc) |
| { |
| unsigned long flags; |
| int ret = 0; |
| |
| if (disc < N_TTY || disc >= NR_LDISCS) |
| return -EINVAL; |
| |
| raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
| tty_ldiscs[disc] = new_ldisc; |
| new_ldisc->num = disc; |
| new_ldisc->refcount = 0; |
| raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(tty_register_ldisc); |
| |
| /** |
| * tty_unregister_ldisc - unload a line discipline |
| * @disc: ldisc number |
| * @new_ldisc: pointer to the ldisc object |
| * |
| * Remove a line discipline from the kernel providing it is not |
| * currently in use. |
| * |
| * Locking: |
| * takes tty_ldiscs_lock to guard against ldisc races |
| */ |
| |
| int tty_unregister_ldisc(int disc) |
| { |
| unsigned long flags; |
| int ret = 0; |
| |
| if (disc < N_TTY || disc >= NR_LDISCS) |
| return -EINVAL; |
| |
| raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
| if (tty_ldiscs[disc]->refcount) |
| ret = -EBUSY; |
| else |
| tty_ldiscs[disc] = NULL; |
| raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(tty_unregister_ldisc); |
| |
| static struct tty_ldisc_ops *get_ldops(int disc) |
| { |
| unsigned long flags; |
| struct tty_ldisc_ops *ldops, *ret; |
| |
| raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
| ret = ERR_PTR(-EINVAL); |
| ldops = tty_ldiscs[disc]; |
| if (ldops) { |
| ret = ERR_PTR(-EAGAIN); |
| if (try_module_get(ldops->owner)) { |
| ldops->refcount++; |
| ret = ldops; |
| } |
| } |
| raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
| return ret; |
| } |
| |
| static void put_ldops(struct tty_ldisc_ops *ldops) |
| { |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&tty_ldiscs_lock, flags); |
| ldops->refcount--; |
| module_put(ldops->owner); |
| raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags); |
| } |
| |
| /** |
| * tty_ldisc_get - take a reference to an ldisc |
| * @disc: ldisc number |
| * |
| * Takes a reference to a line discipline. Deals with refcounts and |
| * module locking counts. |
| * |
| * Returns: -EINVAL if the discipline index is not [N_TTY..NR_LDISCS] or |
| * if the discipline is not registered |
| * -EAGAIN if request_module() failed to load or register the |
| * the discipline |
| * -ENOMEM if allocation failure |
| * |
| * Otherwise, returns a pointer to the discipline and bumps the |
| * ref count |
| * |
| * Locking: |
| * takes tty_ldiscs_lock to guard against ldisc races |
| */ |
| |
| #if defined(CONFIG_LDISC_AUTOLOAD) |
| #define INITIAL_AUTOLOAD_STATE 1 |
| #else |
| #define INITIAL_AUTOLOAD_STATE 0 |
| #endif |
| static int tty_ldisc_autoload = INITIAL_AUTOLOAD_STATE; |
| |
| static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) |
| { |
| struct tty_ldisc *ld; |
| struct tty_ldisc_ops *ldops; |
| |
| if (disc < N_TTY || disc >= NR_LDISCS) |
| return ERR_PTR(-EINVAL); |
| |
| /* |
| * Get the ldisc ops - we may need to request them to be loaded |
| * dynamically and try again. |
| */ |
| ldops = get_ldops(disc); |
| if (IS_ERR(ldops)) { |
| if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload) |
| return ERR_PTR(-EPERM); |
| request_module("tty-ldisc-%d", disc); |
| ldops = get_ldops(disc); |
| if (IS_ERR(ldops)) |
| return ERR_CAST(ldops); |
| } |
| |
| /* |
| * There is no way to handle allocation failure of only 16 bytes. |
| * Let's simplify error handling and save more memory. |
| */ |
| ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL); |
| ld->ops = ldops; |
| ld->tty = tty; |
| |
| return ld; |
| } |
| |
| /** |
| * tty_ldisc_put - release the ldisc |
| * |
| * Complement of tty_ldisc_get(). |
| */ |
| static void tty_ldisc_put(struct tty_ldisc *ld) |
| { |
| if (WARN_ON_ONCE(!ld)) |
| return; |
| |
| put_ldops(ld->ops); |
| kfree(ld); |
| } |
| |
| static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) |
| { |
| return (*pos < NR_LDISCS) ? pos : NULL; |
| } |
| |
| static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) |
| { |
| (*pos)++; |
| return (*pos < NR_LDISCS) ? pos : NULL; |
| } |
| |
| static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) |
| { |
| } |
| |
| static int tty_ldiscs_seq_show(struct seq_file *m, void *v) |
| { |
| int i = *(loff_t *)v; |
| struct tty_ldisc_ops *ldops; |
| |
| ldops = get_ldops(i); |
| if (IS_ERR(ldops)) |
| return 0; |
| seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i); |
| put_ldops(ldops); |
| return 0; |
| } |
| |
| static const struct seq_operations tty_ldiscs_seq_ops = { |
| .start = tty_ldiscs_seq_start, |
| .next = tty_ldiscs_seq_next, |
| .stop = tty_ldiscs_seq_stop, |
| .show = tty_ldiscs_seq_show, |
| }; |
| |
| static int proc_tty_ldiscs_open(struct inode *inode, struct file *file) |
| { |
| return seq_open(file, &tty_ldiscs_seq_ops); |
| } |
| |
| const struct file_operations tty_ldiscs_proc_fops = { |
| .owner = THIS_MODULE, |
| .open = proc_tty_ldiscs_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = seq_release, |
| }; |
| |
| /** |
| * tty_ldisc_ref_wait - wait for the tty ldisc |
| * @tty: tty device |
| * |
| * Dereference the line discipline for the terminal and take a |
| * reference to it. If the line discipline is in flux then |
| * wait patiently until it changes. |
| * |
| * Returns: NULL if the tty has been hungup and not re-opened with |
| * a new file descriptor, otherwise valid ldisc reference |
| * |
| * Note: Must not be called from an IRQ/timer context. The caller |
| * must also be careful not to hold other locks that will deadlock |
| * against a discipline change, such as an existing ldisc reference |
| * (which we check for) |
| * |
| * Note: a file_operations routine (read/poll/write) should use this |
| * function to wait for any ldisc lifetime events to finish. |
| */ |
| |
| struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) |
| { |
| struct tty_ldisc *ld; |
| |
| ldsem_down_read(&tty->ldisc_sem, MAX_SCHEDULE_TIMEOUT); |
| ld = tty->ldisc; |
| if (!ld) |
| ldsem_up_read(&tty->ldisc_sem); |
| return ld; |
| } |
| EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); |
| |
| /** |
| * tty_ldisc_ref - get the tty ldisc |
| * @tty: tty device |
| * |
| * Dereference the line discipline for the terminal and take a |
| * reference to it. If the line discipline is in flux then |
| * return NULL. Can be called from IRQ and timer functions. |
| */ |
| |
| struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) |
| { |
| struct tty_ldisc *ld = NULL; |
| |
| if (ldsem_down_read_trylock(&tty->ldisc_sem)) { |
| ld = tty->ldisc; |
| if (!ld) |
| ldsem_up_read(&tty->ldisc_sem); |
| } |
| return ld; |
| } |
| EXPORT_SYMBOL_GPL(tty_ldisc_ref); |
| |
| /** |
| * tty_ldisc_deref - free a tty ldisc reference |
| * @ld: reference to free up |
| * |
| * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May |
| * be called in IRQ context. |
| */ |
| |
| void tty_ldisc_deref(struct tty_ldisc *ld) |
| { |
| ldsem_up_read(&ld->tty->ldisc_sem); |
| } |
| EXPORT_SYMBOL_GPL(tty_ldisc_deref); |
| |
| |
| static inline int |
| __tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
| { |
| return ldsem_down_write(&tty->ldisc_sem, timeout); |
| } |
| |
| static inline int |
| __tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout) |
| { |
| return ldsem_down_write_nested(&tty->ldisc_sem, |
| LDISC_SEM_OTHER, timeout); |
| } |
| |
| static inline void __tty_ldisc_unlock(struct tty_struct *tty) |
| { |
| ldsem_up_write(&tty->ldisc_sem); |
| } |
| |
| int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) |
| { |
| int ret; |
| |
| ret = __tty_ldisc_lock(tty, timeout); |
| if (!ret) |
| return -EBUSY; |
| set_bit(TTY_LDISC_HALTED, &tty->flags); |
| return 0; |
| } |
| |
| void tty_ldisc_unlock(struct tty_struct *tty) |
| { |
| clear_bit(TTY_LDISC_HALTED, &tty->flags); |
| __tty_ldisc_unlock(tty); |
| } |
| |
| static int |
| tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2, |
| unsigned long timeout) |
| { |
| int ret; |
| |
| if (tty < tty2) { |
| ret = __tty_ldisc_lock(tty, timeout); |
| if (ret) { |
| ret = __tty_ldisc_lock_nested(tty2, timeout); |
| if (!ret) |
| __tty_ldisc_unlock(tty); |
| } |
| } else { |
| /* if this is possible, it has lots of implications */ |
| WARN_ON_ONCE(tty == tty2); |
| if (tty2 && tty != tty2) { |
| ret = __tty_ldisc_lock(tty2, timeout); |
| if (ret) { |
| ret = __tty_ldisc_lock_nested(tty, timeout); |
| if (!ret) |
| __tty_ldisc_unlock(tty2); |
| } |
| } else |
| ret = __tty_ldisc_lock(tty, timeout); |
| } |
| |
| if (!ret) |
| return -EBUSY; |
| |
| set_bit(TTY_LDISC_HALTED, &tty->flags); |
| if (tty2) |
| set_bit(TTY_LDISC_HALTED, &tty2->flags); |
| return 0; |
| } |
| |
| static void tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2) |
| { |
| tty_ldisc_lock_pair_timeout(tty, tty2, MAX_SCHEDULE_TIMEOUT); |
| } |
| |
| static void tty_ldisc_unlock_pair(struct tty_struct *tty, |
| struct tty_struct *tty2) |
| { |
| __tty_ldisc_unlock(tty); |
| if (tty2) |
| __tty_ldisc_unlock(tty2); |
| } |
| |
| /** |
| * tty_ldisc_flush - flush line discipline queue |
| * @tty: tty |
| * |
| * Flush the line discipline queue (if any) and the tty flip buffers |
| * for this tty. |
| */ |
| |
| void tty_ldisc_flush(struct tty_struct *tty) |
| { |
| struct tty_ldisc *ld = tty_ldisc_ref(tty); |
| |
| tty_buffer_flush(tty, ld); |
| if (ld) |
| tty_ldisc_deref(ld); |
| } |
| EXPORT_SYMBOL_GPL(tty_ldisc_flush); |
| |
| /** |
| * tty_set_termios_ldisc - set ldisc field |
| * @tty: tty structure |
| * @disc: line discipline number |
| * |
| * This is probably overkill for real world processors but |
| * they are not on hot paths so a little discipline won't do |
| * any harm. |
| * |
| * The line discipline-related tty_struct fields are reset to |
| * prevent the ldisc driver from re-using stale information for |
| * the new ldisc instance. |
| * |
| * Locking: takes termios_rwsem |
| */ |
| |
| static void tty_set_termios_ldisc(struct tty_struct *tty, int disc) |
| { |
| down_write(&tty->termios_rwsem); |
| tty->termios.c_line = disc; |
| up_write(&tty->termios_rwsem); |
| |
| tty->disc_data = NULL; |
| tty->receive_room = 0; |
| } |
| |
| /** |
| * tty_ldisc_open - open a line discipline |
| * @tty: tty we are opening the ldisc on |
| * @ld: discipline to open |
| * |
| * A helper opening method. Also a convenient debugging and check |
| * point. |
| * |
| * Locking: always called with BTM already held. |
| */ |
| |
| static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) |
| { |
| WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); |
| if (ld->ops->open) { |
| int ret; |
| /* BTM here locks versus a hangup event */ |
| ret = ld->ops->open(tty); |
| if (ret) |
| clear_bit(TTY_LDISC_OPEN, &tty->flags); |
| |
| tty_ldisc_debug(tty, "%p: opened\n", ld); |
| return ret; |
| } |
| return 0; |
| } |
| |
| /** |
| * tty_ldisc_close - close a line discipline |
| * @tty: tty we are opening the ldisc on |
| * @ld: discipline to close |
| * |
| * A helper close method. Also a convenient debugging and check |
| * point. |
| */ |
| |
| static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) |
| { |
| WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); |
| clear_bit(TTY_LDISC_OPEN, &tty->flags); |
| if (ld->ops->close) |
| ld->ops->close(tty); |
| tty_ldisc_debug(tty, "%p: closed\n", ld); |
| } |
| |
| /** |
| * tty_ldisc_failto - helper for ldisc failback |
| * @tty: tty to open the ldisc on |
| * @ld: ldisc we are trying to fail back to |
| * |
| * Helper to try and recover a tty when switching back to the old |
| * ldisc fails and we need something attached. |
| */ |
| |
| static int tty_ldisc_failto(struct tty_struct *tty, int ld) |
| { |
| struct tty_ldisc *disc = tty_ldisc_get(tty, ld); |
| int r; |
| |
| if (IS_ERR(disc)) |
| return PTR_ERR(disc); |
| tty->ldisc = disc; |
| tty_set_termios_ldisc(tty, ld); |
| if ((r = tty_ldisc_open(tty, disc)) < 0) |
| tty_ldisc_put(disc); |
| return r; |
| } |
| |
| /** |
| * tty_ldisc_restore - helper for tty ldisc change |
| * @tty: tty to recover |
| * @old: previous ldisc |
| * |
| * Restore the previous line discipline or N_TTY when a line discipline |
| * change fails due to an open error |
| */ |
| |
| static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) |
| { |
| /* There is an outstanding reference here so this is safe */ |
| if (tty_ldisc_failto(tty, old->ops->num) < 0) { |
| const char *name = tty_name(tty); |
| |
| pr_warn("Falling back ldisc for %s.\n", name); |
| /* The traditional behaviour is to fall back to N_TTY, we |
| want to avoid falling back to N_NULL unless we have no |
| choice to avoid the risk of breaking anything */ |
| if (tty_ldisc_failto(tty, N_TTY) < 0 && |
| tty_ldisc_failto(tty, N_NULL) < 0) |
| panic("Couldn't open N_NULL ldisc for %s.", name); |
| } |
| } |
| |
| /** |
| * tty_set_ldisc - set line discipline |
| * @tty: the terminal to set |
| * @ldisc: the line discipline |
| * |
| * Set the discipline of a tty line. Must be called from a process |
| * context. The ldisc change logic has to protect itself against any |
| * overlapping ldisc change (including on the other end of pty pairs), |
| * the close of one side of a tty/pty pair, and eventually hangup. |
| */ |
| |
| int tty_set_ldisc(struct tty_struct *tty, int disc) |
| { |
| int retval; |
| struct tty_ldisc *old_ldisc, *new_ldisc; |
| |
| new_ldisc = tty_ldisc_get(tty, disc); |
| if (IS_ERR(new_ldisc)) |
| return PTR_ERR(new_ldisc); |
| |
| tty_lock(tty); |
| retval = tty_ldisc_lock(tty, 5 * HZ); |
| if (retval) |
| goto err; |
| |
| if (!tty->ldisc) { |
| retval = -EIO; |
| goto out; |
| } |
| |
| /* Check the no-op case */ |
| if (tty->ldisc->ops->num == disc) |
| goto out; |
| |
| if (test_bit(TTY_HUPPED, &tty->flags)) { |
| /* We were raced by hangup */ |
| retval = -EIO; |
| goto out; |
| } |
| |
| old_ldisc = tty->ldisc; |
| |
| /* Shutdown the old discipline. */ |
| tty_ldisc_close(tty, old_ldisc); |
| |
| /* Now set up the new line discipline. */ |
| tty->ldisc = new_ldisc; |
| tty_set_termios_ldisc(tty, disc); |
| |
| retval = tty_ldisc_open(tty, new_ldisc); |
| if (retval < 0) { |
| /* Back to the old one or N_TTY if we can't */ |
| tty_ldisc_put(new_ldisc); |
| tty_ldisc_restore(tty, old_ldisc); |
| } |
| |
| if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) { |
| down_read(&tty->termios_rwsem); |
| tty->ops->set_ldisc(tty); |
| up_read(&tty->termios_rwsem); |
| } |
| |
| /* At this point we hold a reference to the new ldisc and a |
| reference to the old ldisc, or we hold two references to |
| the old ldisc (if it was restored as part of error cleanup |
| above). In either case, releasing a single reference from |
| the old ldisc is correct. */ |
| new_ldisc = old_ldisc; |
| out: |
| tty_ldisc_unlock(tty); |
| |
| /* Restart the work queue in case no characters kick it off. Safe if |
| already running */ |
| tty_buffer_restart_work(tty->port); |
| err: |
| tty_ldisc_put(new_ldisc); /* drop the extra reference */ |
| tty_unlock(tty); |
| return retval; |
| } |
| EXPORT_SYMBOL_GPL(tty_set_ldisc); |
| |
| /** |
| * tty_ldisc_kill - teardown ldisc |
| * @tty: tty being released |
| * |
| * Perform final close of the ldisc and reset tty->ldisc |
| */ |
| static void tty_ldisc_kill(struct tty_struct *tty) |
| { |
| if (!tty->ldisc) |
| return; |
| /* |
| * Now kill off the ldisc |
| */ |
| tty_ldisc_close(tty, tty->ldisc); |
| tty_ldisc_put(tty->ldisc); |
| /* Force an oops if we mess this up */ |
| tty->ldisc = NULL; |
| } |
| |
| /** |
| * tty_reset_termios - reset terminal state |
| * @tty: tty to reset |
| * |
| * Restore a terminal to the driver default state. |
| */ |
| |
| static void tty_reset_termios(struct tty_struct *tty) |
| { |
| down_write(&tty->termios_rwsem); |
| tty->termios = tty->driver->init_termios; |
| tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios); |
| tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios); |
| up_write(&tty->termios_rwsem); |
| } |
| |
| |
| /** |
| * tty_ldisc_reinit - reinitialise the tty ldisc |
| * @tty: tty to reinit |
| * @disc: line discipline to reinitialize |
| * |
| * Completely reinitialize the line discipline state, by closing the |
| * current instance, if there is one, and opening a new instance. If |
| * an error occurs opening the new non-N_TTY instance, the instance |
| * is dropped and tty->ldisc reset to NULL. The caller can then retry |
| * with N_TTY instead. |
| * |
| * Returns 0 if successful, otherwise error code < 0 |
| */ |
| |
| int tty_ldisc_reinit(struct tty_struct *tty, int disc) |
| { |
| struct tty_ldisc *ld; |
| int retval; |
| |
| ld = tty_ldisc_get(tty, disc); |
| if (IS_ERR(ld)) { |
| BUG_ON(disc == N_TTY); |
| return PTR_ERR(ld); |
| } |
| |
| if (tty->ldisc) { |
| tty_ldisc_close(tty, tty->ldisc); |
| tty_ldisc_put(tty->ldisc); |
| } |
| |
| /* switch the line discipline */ |
| tty->ldisc = ld; |
| tty_set_termios_ldisc(tty, disc); |
| retval = tty_ldisc_open(tty, tty->ldisc); |
| if (retval) { |
| tty_ldisc_put(tty->ldisc); |
| tty->ldisc = NULL; |
| } |
| return retval; |
| } |
| |
| /** |
| * tty_ldisc_hangup - hangup ldisc reset |
| * @tty: tty being hung up |
| * |
| * Some tty devices reset their termios when they receive a hangup |
| * event. In that situation we must also switch back to N_TTY properly |
| * before we reset the termios data. |
| * |
| * Locking: We can take the ldisc mutex as the rest of the code is |
| * careful to allow for this. |
| * |
| * In the pty pair case this occurs in the close() path of the |
| * tty itself so we must be careful about locking rules. |
| */ |
| |
| void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) |
| { |
| struct tty_ldisc *ld; |
| |
| tty_ldisc_debug(tty, "%p: hangup\n", tty->ldisc); |
| |
| ld = tty_ldisc_ref(tty); |
| if (ld != NULL) { |
| if (ld->ops->flush_buffer) |
| ld->ops->flush_buffer(tty); |
| tty_driver_flush_buffer(tty); |
| if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && |
| ld->ops->write_wakeup) |
| ld->ops->write_wakeup(tty); |
| if (ld->ops->hangup) |
| ld->ops->hangup(tty); |
| tty_ldisc_deref(ld); |
| } |
| |
| wake_up_interruptible_poll(&tty->write_wait, POLLOUT); |
| wake_up_interruptible_poll(&tty->read_wait, POLLIN); |
| |
| /* |
| * Shutdown the current line discipline, and reset it to |
| * N_TTY if need be. |
| * |
| * Avoid racing set_ldisc or tty_ldisc_release |
| */ |
| tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); |
| |
| if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) |
| tty_reset_termios(tty); |
| |
| if (tty->ldisc) { |
| if (reinit) { |
| if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0 && |
| tty_ldisc_reinit(tty, N_TTY) < 0) |
| WARN_ON(tty_ldisc_reinit(tty, N_NULL) < 0); |
| } else |
| tty_ldisc_kill(tty); |
| } |
| tty_ldisc_unlock(tty); |
| } |
| |
| /** |
| * tty_ldisc_setup - open line discipline |
| * @tty: tty being shut down |
| * @o_tty: pair tty for pty/tty pairs |
| * |
| * Called during the initial open of a tty/pty pair in order to set up the |
| * line disciplines and bind them to the tty. This has no locking issues |
| * as the device isn't yet active. |
| */ |
| |
| int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) |
| { |
| int retval = tty_ldisc_open(tty, tty->ldisc); |
| if (retval) |
| return retval; |
| |
| if (o_tty) { |
| retval = tty_ldisc_open(o_tty, o_tty->ldisc); |
| if (retval) { |
| tty_ldisc_close(tty, tty->ldisc); |
| return retval; |
| } |
| } |
| return 0; |
| } |
| |
| /** |
| * tty_ldisc_release - release line discipline |
| * @tty: tty being shut down (or one end of pty pair) |
| * |
| * Called during the final close of a tty or a pty pair in order to shut |
| * down the line discpline layer. On exit, each tty's ldisc is NULL. |
| */ |
| |
| void tty_ldisc_release(struct tty_struct *tty) |
| { |
| struct tty_struct *o_tty = tty->link; |
| |
| /* |
| * Shutdown this line discipline. As this is the final close, |
| * it does not race with the set_ldisc code path. |
| */ |
| |
| tty_ldisc_lock_pair(tty, o_tty); |
| tty_ldisc_kill(tty); |
| if (o_tty) |
| tty_ldisc_kill(o_tty); |
| tty_ldisc_unlock_pair(tty, o_tty); |
| |
| /* And the memory resources remaining (buffers, termios) will be |
| disposed of when the kref hits zero */ |
| |
| tty_ldisc_debug(tty, "released\n"); |
| } |
| EXPORT_SYMBOL_GPL(tty_ldisc_release); |
| |
| /** |
| * tty_ldisc_init - ldisc setup for new tty |
| * @tty: tty being allocated |
| * |
| * Set up the line discipline objects for a newly allocated tty. Note that |
| * the tty structure is not completely set up when this call is made. |
| */ |
| |
| int tty_ldisc_init(struct tty_struct *tty) |
| { |
| struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY); |
| if (IS_ERR(ld)) |
| return PTR_ERR(ld); |
| tty->ldisc = ld; |
| return 0; |
| } |
| |
| /** |
| * tty_ldisc_deinit - ldisc cleanup for new tty |
| * @tty: tty that was allocated recently |
| * |
| * The tty structure must not becompletely set up (tty_ldisc_setup) when |
| * this call is made. |
| */ |
| void tty_ldisc_deinit(struct tty_struct *tty) |
| { |
| if (tty->ldisc) |
| tty_ldisc_put(tty->ldisc); |
| tty->ldisc = NULL; |
| } |
| |
| static int zero; |
| static int one = 1; |
| static struct ctl_table tty_table[] = { |
| { |
| .procname = "ldisc_autoload", |
| .data = &tty_ldisc_autoload, |
| .maxlen = sizeof(tty_ldisc_autoload), |
| .mode = 0644, |
| .proc_handler = proc_dointvec, |
| .extra1 = &zero, |
| .extra2 = &one, |
| }, |
| { } |
| }; |
| |
| static struct ctl_table tty_dir_table[] = { |
| { |
| .procname = "tty", |
| .mode = 0555, |
| .child = tty_table, |
| }, |
| { } |
| }; |
| |
| static struct ctl_table tty_root_table[] = { |
| { |
| .procname = "dev", |
| .mode = 0555, |
| .child = tty_dir_table, |
| }, |
| { } |
| }; |
| |
| void tty_sysctl_init(void) |
| { |
| register_sysctl_table(tty_root_table); |
| } |