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path: root/drivers/tty/tty_ldisc.c
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Diffstat (limited to 'drivers/tty/tty_ldisc.c')
-rw-r--r--drivers/tty/tty_ldisc.c49
1 files changed, 42 insertions, 7 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 412f9775d19..d8e96b00502 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -47,6 +47,7 @@
static DEFINE_SPINLOCK(tty_ldisc_lock);
static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
+static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle);
/* Line disc dispatch table */
static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
@@ -83,6 +84,7 @@ static void put_ldisc(struct tty_ldisc *ld)
return;
}
local_irq_restore(flags);
+ wake_up(&tty_ldisc_idle);
}
/**
@@ -531,6 +533,23 @@ static int tty_ldisc_halt(struct tty_struct *tty)
}
/**
+ * 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 int tty_ldisc_wait_idle(struct tty_struct *tty)
+{
+ int ret;
+ ret = wait_event_interruptible_timeout(tty_ldisc_idle,
+ atomic_read(&tty->ldisc->users) == 1, 5 * HZ);
+ if (ret < 0)
+ return ret;
+ return ret > 0 ? 0 : -EBUSY;
+}
+
+/**
* tty_set_ldisc - set line discipline
* @tty: the terminal to set
* @ldisc: the line discipline
@@ -634,8 +653,17 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
flush_scheduled_work();
+ retval = tty_ldisc_wait_idle(tty);
+
tty_lock();
mutex_lock(&tty->ldisc_mutex);
+
+ /* handle wait idle failure locked */
+ if (retval) {
+ tty_ldisc_put(new_ldisc);
+ goto enable;
+ }
+
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 */
@@ -669,6 +697,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_ldisc_put(o_ldisc);
+enable:
/*
* Allow ldisc referencing to occur again
*/
@@ -714,9 +743,12 @@ static void tty_reset_termios(struct tty_struct *tty)
* state closed
*/
-static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
+static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
{
- struct tty_ldisc *ld;
+ struct tty_ldisc *ld = tty_ldisc_get(ldisc);
+
+ if (IS_ERR(ld))
+ return -1;
tty_ldisc_close(tty, tty->ldisc);
tty_ldisc_put(tty->ldisc);
@@ -724,10 +756,10 @@ static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
/*
* Switch the line discipline back
*/
- ld = tty_ldisc_get(ldisc);
- BUG_ON(IS_ERR(ld));
tty_ldisc_assign(tty, ld);
tty_set_termios_ldisc(tty, ldisc);
+
+ return 0;
}
/**
@@ -802,13 +834,16 @@ void tty_ldisc_hangup(struct tty_struct *tty)
a FIXME */
if (tty->ldisc) { /* Not yet closed */
if (reset == 0) {
- tty_ldisc_reinit(tty, tty->termios->c_line);
- err = tty_ldisc_open(tty, tty->ldisc);
+
+ if (!tty_ldisc_reinit(tty, tty->termios->c_line))
+ err = tty_ldisc_open(tty, tty->ldisc);
+ else
+ err = 1;
}
/* If the re-open fails or we reset then go to N_TTY. The
N_TTY open cannot fail */
if (reset || err) {
- tty_ldisc_reinit(tty, N_TTY);
+ BUG_ON(tty_ldisc_reinit(tty, N_TTY));
WARN_ON(tty_ldisc_open(tty, tty->ldisc));
}
tty_ldisc_enable(tty);