tty: BKL pushdown
- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock
BKL now primarily protects open/close/ldisc change in the tty layer
[jirislaby@gmail.com: a couple of fixes]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 706ff347..6288356 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -181,6 +181,7 @@
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
+ unsigned long flags;
if (!to)
return;
@@ -189,8 +190,10 @@
to->ldisc.flush_buffer(to);
if (to->packet) {
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
wake_up_interruptible(&to->read_wait);
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
}
}