![Linus Torvalds](/assets/img/avatar_default.png)
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
848 lines
20 KiB
C
848 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#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
|
|
*/
|
|
|
|
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)) {
|
|
request_module("tty-ldisc-%d", disc);
|
|
ldops = get_ldops(disc);
|
|
if (IS_ERR(ldops))
|
|
return ERR_CAST(ldops);
|
|
}
|
|
|
|
ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL);
|
|
if (ld == NULL) {
|
|
put_ldops(ldops);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
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 */
|
|
old = tty_ldisc_get(tty, old->ops->num);
|
|
WARN_ON(IS_ERR(old));
|
|
tty->ldisc = old;
|
|
tty_set_termios_ldisc(tty, old->ops->num);
|
|
if (tty_ldisc_open(tty, old) < 0) {
|
|
tty_ldisc_put(old);
|
|
/* 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.",
|
|
tty_name(tty));
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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, EPOLLOUT);
|
|
wake_up_interruptible_poll(&tty->read_wait, EPOLLIN);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
void tty_ldisc_init(struct tty_struct *tty)
|
|
{
|
|
struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY);
|
|
if (IS_ERR(ld))
|
|
panic("n_tty: init_tty");
|
|
tty->ldisc = ld;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
}
|