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path: root/drivers/char/tty_ldisc.c
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Diffstat (limited to 'drivers/char/tty_ldisc.c')
-rw-r--r--drivers/char/tty_ldisc.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index feb55075819b..3f653f7d849f 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -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>
@@ -443,8 +445,14 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
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)
- return ld->ops->open(tty);
+ if (ld->ops->open) {
+ int ret;
+ /* BKL here locks verus a hangup event */
+ lock_kernel();
+ ret = ld->ops->open(tty);
+ unlock_kernel();
+ return ret;
+ }
return 0;
}
@@ -545,6 +553,7 @@ 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.
@@ -558,10 +567,12 @@ 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;
}
+ unlock_kernel();
/*
* Problem: What do we do if this blocks ?
* We could deadlock here
@@ -582,6 +593,9 @@ 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 +606,8 @@ 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 +633,14 @@ 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 +682,7 @@ 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;
}