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>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 6c81739..be49d07 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2481,6 +2481,24 @@
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 @@
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
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index f78f5b0..e3c6416 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -444,6 +444,50 @@
}
/**
+ * 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
* @ldisc: the line discipline
@@ -636,6 +680,21 @@
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 @@
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);
}
}