[3.8.y.z extended stable] Patch "tty: Set correct tty name in 'active' sysfs attribute" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    tty: Set correct tty name in 'active' sysfs attribute

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.22.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 1ff72ce333d75802cc614e60d5bf03d2d670090b Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare at suse.de>
Date: Thu, 27 Feb 2014 12:30:51 +0100
Subject: tty: Set correct tty name in 'active' sysfs attribute

commit 723abd87f6e536f1353c8f64f621520bc29523a3 upstream.

The 'active' sysfs attribute should refer to the currently active tty
devices the console is running on, not the currently active console. The
console structure doesn't refer to any device in sysfs, only the tty the
console is running on has. So we need to print out the tty names in
'active', not the console names.

There is one special-case, which is tty0. If the console is directed to
it, we want 'tty0' to show up in the file, so user-space knows that the
messages get forwarded to the active VT. The ->device() callback would
resolve tty0, though. Hence, treat it special and don't call into the VT
layer to resolve it (plymouth is known to depend on it).

Cc: Lennart Poettering <lennart at poettering.net>
Cc: Kay Sievers <kay at vrfy.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Jiri Slaby <jslaby at suse.cz>
Signed-off-by: Werner Fink <werner at suse.de>
Signed-off-by: Hannes Reinecke <hare at suse.de>
Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/tty/tty_io.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index f34f98d..70f8c19 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1221,12 +1221,13 @@ static void pty_line_name(struct tty_driver *driver, int index, char *p)
  *
  *	Locking: None
  */
-static void tty_line_name(struct tty_driver *driver, int index, char *p)
+static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
 {
 	if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
-		strcpy(p, driver->name);
+		return sprintf(p, "%s", driver->name);
 	else
-		sprintf(p, "%s%d", driver->name, index + driver->name_base);
+		return sprintf(p, "%s%d", driver->name,
+			       index + driver->name_base);
 }

 /**
@@ -3472,9 +3473,19 @@ static ssize_t show_cons_active(struct device *dev,
 		if (i >= ARRAY_SIZE(cs))
 			break;
 	}
-	while (i--)
-		count += sprintf(buf + count, "%s%d%c",
-				 cs[i]->name, cs[i]->index, i ? ' ':'\n');
+	while (i--) {
+		int index = cs[i]->index;
+		struct tty_driver *drv = cs[i]->device(cs[i], &index);
+
+		/* don't resolve tty0 as some programs depend on it */
+		if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
+			count += tty_line_name(drv, index, buf + count);
+		else
+			count += sprintf(buf + count, "%s%d",
+					 cs[i]->name, cs[i]->index);
+
+		count += sprintf(buf + count, "%c", i ? ' ':'\n');
+	}
 	console_unlock();

 	return count;
--
1.9.1