From c65c9bc3efa5589f691276bb9db689119a711222 Mon Sep 17 00:00:00 2001 From: Alan Cox <alan@linux.intel.com> Date: Thu, 11 Jun 2009 12:50:12 +0100 Subject: tty: rewrite the ldisc locking There are several pretty much unfixable races in the old ldisc code, especially with respect to pty behaviour and also to hangup. It's easier to rewrite the code than simply try and patch it up. This patch - splits the ldisc from the tty (so we will be able to refcount it more cleanly later) - introduces a mutex lock for ldisc changing on an active device - fixes the complete mess that hangup caused - implements hopefully correct setldisc/close/hangup locking There are still some problems around pty pairs that have always been there but at least it is now possible to understand the code and fix further problems. This fixes the following known bugs - hang up can leak ldisc references - hang up may not call open/close on ldisc in a matched way - pty/tty pairs can deadlock during an ldisc change - reading the ldisc proc files can cause every ldisc to be loaded and probably a few other of the mysterious ldisc race reports. I'm sure it also adds the odd new one. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- drivers/bluetooth/hci_ldisc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/bluetooth/hci_ldisc.c') diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index af761dc434f..68801512859 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -277,8 +277,8 @@ static int hci_uart_tty_open(struct tty_struct *tty) /* FIXME: why is this needed. Note don't use ldisc_ref here as the open path is before the ldisc is referencable */ - if (tty->ldisc.ops->flush_buffer) - tty->ldisc.ops->flush_buffer(tty); + if (tty->ldisc->ops->flush_buffer) + tty->ldisc->ops->flush_buffer(tty); tty_driver_flush_buffer(tty); return 0; -- cgit v1.2.3-70-g09d2 From 7f8d09eae26a8108406583192996561665b36371 Mon Sep 17 00:00:00 2001 From: Alan Cox <alan@linux.intel.com> Date: Thu, 11 Jun 2009 13:56:16 +0100 Subject: tty: fix bluetooth scribbling on low latency flags Bluetooth shouldn't be doing this as most drivers don't support the flag, furthermore it shouldn't be needed with newer buffering. This becomes rather more visible as the locking fixes make the abuse of low_latency visible as spew on the users console/dmesg. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- drivers/bluetooth/hci_ldisc.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/bluetooth/hci_ldisc.c') diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index 68801512859..4895f0e0532 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -463,7 +463,6 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file * file, clear_bit(HCI_UART_PROTO_SET, &hu->flags); return err; } - tty->low_latency = 1; } else return -EBUSY; break; -- cgit v1.2.3-70-g09d2