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tty: Extract various bits of ldisc code 

Before trying to tackle the ldisc bugs the code needs to be a good deal
more readable, so do the simple extractions of routines first.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2009-06-11 12:48:02 +01:00 committed by Linus Torvalds
parent 5f0878acba
commit e8b70e7d3e
3 changed files with 88 additions and 36 deletions
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24
drivers/char/tty_io.c
View File

@ -2481,6 +2481,24 @@ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int
return tty->ops->tiocmset(tty, file, set, clear);
}
struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
tty = tty->link;
return tty;
}
EXPORT_SYMBOL(tty_pair_get_tty);
struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
return tty;
return tty->link;
}
EXPORT_SYMBOL(tty_pair_get_pty);
/*
* Split this up, as gcc can choke on it otherwise..
*/
@ -2496,11 +2514,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (tty_paranoia_check(tty, inode, "tty_ioctl"))
return -EINVAL;
real_tty = tty;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
real_tty = tty->link;
real_tty = tty_pair_get_tty(tty);
/*
* Factor out some common prep work

97
drivers/char/tty_ldisc.c
View File

@ -443,6 +443,50 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
}
}
/**
* tty_ldisc_halt - shutdown the line discipline
* @tty: tty device
*
* Shut down the line discipline and work queue for this tty device.
* The TTY_LDISC flag being cleared ensures no further references can
* be obtained while the delayed work queue halt ensures that no more
* data is fed to the ldisc.
*
* In order to wait for any existing references to complete see
* tty_ldisc_wait_idle.
*/
static void tty_ldisc_halt(struct tty_struct *tty)
{
clear_bit(TTY_LDISC, &tty->flags);
cancel_delayed_work(&tty->buf.work);
/*
* Wait for ->hangup_work and ->buf.work handlers to terminate
*/
flush_scheduled_work();
}
/**
* tty_ldisc_wait_idle - wait for the ldisc to become idle
* @tty: tty to wait for
*
* Wait for the line discipline to become idle. The discipline must
* have been halted for this to guarantee it remains idle.
*
*/
static void tty_ldisc_wait_idle(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty_ldisc_lock, flags);
while (tty->ldisc.refcount) {
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
spin_lock_irqsave(&tty_ldisc_lock, flags);
}
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
}
/**
* tty_set_ldisc - set line discipline
* @tty: the terminal to set
@ -636,6 +680,21 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
return 0;
}
static void tty_ldisc_reinit(struct tty_struct *tty)
{
struct tty_ldisc ld;
if (tty->ldisc.ops->close)
(tty->ldisc.ops->close)(tty);
tty_ldisc_put(tty->ldisc.ops);
/*
* Switch the line discipline back
*/
WARN_ON(tty_ldisc_get(N_TTY, &ld));
tty_ldisc_assign(tty, &ld);
tty_set_termios_ldisc(tty, N_TTY);
}
/**
* tty_ldisc_release - release line discipline
* @tty: tty being shut down
@ -647,58 +706,34 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
{
unsigned long flags;
struct tty_ldisc ld;
/*
* Prevent flush_to_ldisc() from rescheduling the work for later. Then
* kill any delayed work. As this is the final close it does not
* race with the set_ldisc code path.
*/
clear_bit(TTY_LDISC, &tty->flags);
cancel_delayed_work(&tty->buf.work);
/*
* Wait for ->hangup_work and ->buf.work handlers to terminate
*/
flush_scheduled_work();
tty_ldisc_halt(tty);
/*
* Wait for any short term users (we know they are just driver
* side waiters as the file is closing so user count on the file
* side is zero.
*/
spin_lock_irqsave(&tty_ldisc_lock, flags);
while (tty->ldisc.refcount) {
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
spin_lock_irqsave(&tty_ldisc_lock, flags);
}
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
tty_ldisc_wait_idle(tty);
/*
* Shutdown the current line discipline, and reset it to N_TTY.
*
* FIXME: this MUST get fixed for the new reflocking
*/
if (tty->ldisc.ops->close)
(tty->ldisc.ops->close)(tty);
tty_ldisc_put(tty->ldisc.ops);
/*
* Switch the line discipline back
*/
WARN_ON(tty_ldisc_get(N_TTY, &ld));
tty_ldisc_assign(tty, &ld);
tty_set_termios_ldisc(tty, N_TTY);
tty_ldisc_reinit(tty);
if (o_tty) {
/* FIXME: could o_tty be in setldisc here ? */
clear_bit(TTY_LDISC, &o_tty->flags);
if (o_tty->ldisc.ops->close)
(o_tty->ldisc.ops->close)(o_tty);
tty_ldisc_put(o_tty->ldisc.ops);
WARN_ON(tty_ldisc_get(N_TTY, &ld));
tty_ldisc_assign(o_tty, &ld);
tty_set_termios_ldisc(o_tty, N_TTY);
tty_ldisc_reinit(o_tty);
}
}

3
include/linux/tty.h
View File

@ -428,6 +428,9 @@ extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
extern void tty_release_dev(struct file *filp);
extern int tty_init_termios(struct tty_struct *tty);
extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);
extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty);
extern struct mutex tty_mutex;
extern void tty_write_unlock(struct tty_struct *tty);