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tty: replace BKL with a new tty_lock

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As a preparation for replacing the big kernel lock
in the TTY layer, wrap all the callers in new
macros tty_lock, tty_lock_nested and tty_unlock.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Arnd Bergmann
2010-06-01 22:53:01 +02:00
committed by Greg Kroah-Hartman
parent 3f582b8c11
commit ec79d6056d
17 changed files with 161 additions and 115 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/char/tty_ldisc.c
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@@ -440,6 +440,8 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
*
* 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)
@@ -447,10 +449,10 @@ 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;
/* BKL here locks verus a hangup event */
lock_kernel();
/* BTM here locks versus a hangup event */
tty_lock_nested(); /* always held here already */
ret = ld->ops->open(tty);
unlock_kernel();
tty_unlock();
return ret;
}
return 0;
@@ -553,7 +555,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (IS_ERR(new_ldisc))
return PTR_ERR(new_ldisc);
lock_kernel();
tty_lock();
/*
* We need to look at the tty locking here for pty/tty pairs
* when both sides try to change in parallel.
@@ -567,12 +569,12 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
*/
if (tty->ldisc->ops->num == ldisc) {
unlock_kernel();
tty_unlock();
tty_ldisc_put(new_ldisc);
return 0;
}
unlock_kernel();
tty_unlock();
/*
* Problem: What do we do if this blocks ?
* We could deadlock here
@@ -594,7 +596,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
mutex_lock(&tty->ldisc_mutex);
}
lock_kernel();
tty_lock();
set_bit(TTY_LDISC_CHANGING, &tty->flags);
@@ -607,7 +609,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
o_ldisc = tty->ldisc;
unlock_kernel();
tty_unlock();
/*
* Make sure we don't change while someone holds a
* reference to the line discipline. The TTY_LDISC bit
@@ -633,14 +635,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
flush_scheduled_work();
mutex_lock(&tty->ldisc_mutex);
lock_kernel();
tty_lock();
if (test_bit(TTY_HUPPED, &tty->flags)) {
/* We were raced by the hangup method. It will have stomped
the ldisc data and closed the ldisc down */
clear_bit(TTY_LDISC_CHANGING, &tty->flags);
mutex_unlock(&tty->ldisc_mutex);
tty_ldisc_put(new_ldisc);
unlock_kernel();
tty_unlock();
return -EIO;
}
@@ -682,7 +684,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (o_work)
schedule_delayed_work(&o_tty->buf.work, 1);
mutex_unlock(&tty->ldisc_mutex);
unlock_kernel();
tty_unlock();
return retval;
}