Thread (28 messages) 28 messages, 4 authors, 2013-03-18

Re: [PATCH v3 3/6] TTY: fix DTR being raised on hang up

From: Peter Hurley <hidden>
Date: 2013-03-15 11:58:08
Also in: lkml

On Fri, 2013-03-15 at 12:30 +0100, Johan Hovold wrote:
On Fri, Mar 15, 2013 at 07:03:08AM -0400, Peter Hurley wrote:
quoted
On Fri, 2013-03-15 at 10:24 +0100, Johan Hovold wrote:
quoted
On Wed, Mar 13, 2013 at 03:43:43PM -0400, Peter Hurley wrote:
quoted
On Thu, 2013-03-07 at 15:55 +0100, Johan Hovold wrote:
quoted
Make sure to check ASYNC_INITIALISED before raising DTR when waking up
from blocked open in tty_port_block_til_ready.

Currently DTR could get raised at hang up as a blocked process would
raise DTR unconditionally before checking for hang up and returning.

Signed-off-by: Johan Hovold <redacted>
---
 drivers/tty/tty_port.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 3de5918..52f1066 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -355,7 +355,7 @@ int tty_port_block_til_ready(struct tty_port *port,
 
 	while (1) {
 		/* Indicate we are open */
-		if (tty->termios.c_cflag & CBAUD)
+		if (C_BAUD(tty) && test_bit(ASYNCB_INITIALIZED, &port->flags))
 			tty_port_raise_dtr_rts(port);
 
 		prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
This is ok, but there are 6 other *_block_til_ready() functions:
     ^^^^^^
Comment on patch
I saw that, but just wanted to stress that those comments shouldn't
block the series.
I completely agree. In fact, I should have said as much in the initial
review. Sorry.
quoted
quoted
Yes, but that's not really a comment on this patch, is it?

The purpose of this series is to fix the tty-port implementation, and
I've only touched individual drivers when I had to in order not to break
anything due to changed assumptions.

There's a ton of buggy and odd behaviour to be found once you start
turning the stones. Drivers like the ones below really ought to be
using tty ports and it's helpers.
Sure, I understand.

OTOH, tty_port and these drivers stem from the same ancestor and it's
partly because of localized bug fixes like these that the drivers have
buggy and odd behavior (because tty_port gets fixed and these do not).
Arguably, fixing the core isn't really a localised bug fix. Some of
those drivers you mentioned have custom open, close, hangup which are
quite different from the tty port implementation, and surely would have
a lot to gain from being ported to tty ports if someone could find the
time to do so.
I think the reluctance to do a full port is partly due to lack of
testable hardware.
quoted
As you can verify from the changelogs of these drivers, it's traditional
to continue to maintain the common aspects, despite the desire to
abandon them.
Most entries I see have to do with changed interfaces.
quoted
That said, I'm not the maintainer so feel free to disagree with my
point-of-view.
You do have a point, and I will try to find the time for a follow-up
series fixing at least a few of those five-or-so custom block_til_ready
you pointed to.
Thanks.

Regards,
Peter Hurley
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