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tty: push the BKL down into the handlers a bit

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Start trying to untangle the remaining BKL mess

Updated to fix missing unlock_kernel noted by Dan Carpenter

Signed-off-by: Alan "I must be out of my tree" Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox
2009-11-30 13:18:29 +00:00
committed by Greg Kroah-Hartman
parent e8c62103fd
commit eeb89d918c
4 changed files with 95 additions and 63 deletions
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13
drivers/char/tty_ldisc.c
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@ -34,6 +34,8 @@
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/smp_lock.h> /* For the moment */
#include <linux/kmod.h>
#include <linux/nsproxy.h>
@ -545,6 +547,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (IS_ERR(new_ldisc))
return PTR_ERR(new_ldisc);
lock_kernel();
/*
* We need to look at the tty locking here for pty/tty pairs
* when both sides try to change in parallel.
@ -558,6 +561,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
*/
if (tty->ldisc->ops->num == ldisc) {
unlock_kernel();
tty_ldisc_put(new_ldisc);
return 0;
}
@ -569,6 +573,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_wait_until_sent(tty, 0);
unlock_kernel();
mutex_lock(&tty->ldisc_mutex);
/*
@ -582,6 +587,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
mutex_lock(&tty->ldisc_mutex);
}
lock_kernel();
set_bit(TTY_LDISC_CHANGING, &tty->flags);
/*
@ -592,6 +600,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty->receive_room = 0;
o_ldisc = tty->ldisc;
unlock_kernel();
/*
* Make sure we don't change while someone holds a
* reference to the line discipline. The TTY_LDISC bit
@ -617,12 +627,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
flush_scheduled_work();
mutex_lock(&tty->ldisc_mutex);
lock_kernel();
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();
return -EIO;
}
@ -664,6 +676,7 @@ 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();
return retval;
}