tty: fix "IRQ45: nobody cared"

Unthrottling the TTY during close ends up enabling interrupts
on a device not on the active list, which will never have the
interrupts cleared.  Doctor, it hurts when I do this.

>>> On 6/2/2011 at 01:56 AM, in message <20110601145608.3e586e16@bob.linux.org.uk>, Alan Cox <alan@linux.intel.com> wrote:
> On Wed, 01 Jun 2011 10:34:07 +1200
> "andrew mcgregor" <andrew.mcgregor@alliedtelesis.co.nz> wrote:
> > The LKML message
> > http://kerneltrap.org/mailarchive/linux-kernel/2010/2/25/4541847 from
> > February doesn't seem to have been resolved since.  We struck the
> > issue, and the patch below (against 2.6.32) fixes it.  Should I
> > supply a patch against 3.0.0rc?
>
> I think that would be sensible. I don't actually see how you hit it as
> the IRQ ought to be masked by then but it's certainly wrong for n_tty
> to be calling into check_unthrottle at that point.
>
> So yes please send a patch with a suitable Signed-off-by: line to
> linux-serial and cc GregKH <greg@kroah.com> as well.
>
> Alan

Signed-off-by: Andrew McGregor <andrew.mcgregor@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ad32888091c16c1c27de4c032517df583ea4c9f..1ddc5d7c9592c9ccdd58bc6954e7a1e431c7379a 100644 (file)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -185,7 +185,6 @@ static void reset_buffer_flags(struct tty_struct *tty)
        tty->canon_head = tty->canon_data = tty->erasing = 0;
        memset(&tty->read_flags, 0, sizeof tty->read_flags);
        n_tty_set_room(tty);
-       check_unthrottle(tty);
 }
 
 /**
@@ -1587,6 +1586,7 @@ static int n_tty_open(struct tty_struct *tty)
                        return -ENOMEM;
        }
        reset_buffer_flags(tty);
+       tty_unthrottle(tty);
        tty->column = 0;
        n_tty_set_termios(tty, NULL);
        tty->minimum_to_wake = 1;