[PATCH] vt: Don't check KD_GRAPHICS when binding/unbinding

From: Daniel Vetter
Date: Mon Apr 13 2015 - 05:16:40 EST


This was introduced in

commit 6db4063c5b72b46e9793b0f141a7a3984ac6facf
Author: Antonino A. Daplas <adaplas@xxxxxxxxx>
Date: Mon Jun 26 00:27:12 2006 -0700

[PATCH] VT binding: Add sysfs control to the VT layer

with the justification

"In addition, if any of the consoles are in KD_GRAPHICS mode, binding and
unbinding will not succeed. KD_GRAPHICS mode usually indicates that the
underlying console hardware is used for other purposes other than displaying
text (ie X). This feature should prevent binding/unbinding from interfering
with a graphics application using the VT."

I think we should lift this artificial restriction though:
- KD_GRAPHICS doesn't get cleaned up automatically, which means it's
easy to have terminals stuck in KD_GRAPHICS when hacking around on
X.
- X doesn't really care, especially with drm where kms already blocks
fbdev (and hence fbcon) when there's an active compositor.
- This is a root-only interface with a separate .config option and
it's possible to hang your machine already anyway if you
unload/reload drivers and don't know what you're doing.

With this patch i915.ko module reloading works again reliably,
something in the recent fedora upgrades broke things.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Antonino A. Daplas <adaplas@xxxxxxxxx>
Cc: David Herrmann <dh.herrmann@xxxxxxxxx>
Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/tty/vt/vt.c | 22 ++--------------------
1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 6e00572cbeb9..b84f7d80c8b4 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3185,22 +3185,6 @@ err:


#ifdef CONFIG_VT_HW_CONSOLE_BINDING
-static int con_is_graphics(const struct consw *csw, int first, int last)
-{
- int i, retval = 0;
-
- for (i = first; i <= last; i++) {
- struct vc_data *vc = vc_cons[i].d;
-
- if (vc && vc->vc_mode == KD_GRAPHICS) {
- retval = 1;
- break;
- }
- }
-
- return retval;
-}
-
/* unlocked version of unbind_con_driver() */
int do_unbind_con_driver(const struct consw *csw, int first, int last, int deflt)
{
@@ -3286,8 +3270,7 @@ static int vt_bind(struct con_driver *con)
const struct consw *defcsw = NULL, *csw = NULL;
int i, more = 1, first = -1, last = -1, deflt = 0;

- if (!con->con || !(con->flag & CON_DRIVER_FLAG_MODULE) ||
- con_is_graphics(con->con, con->first, con->last))
+ if (!con->con || !(con->flag & CON_DRIVER_FLAG_MODULE))
goto err;

csw = con->con;
@@ -3338,8 +3321,7 @@ static int vt_unbind(struct con_driver *con)
int i, more = 1, first = -1, last = -1, deflt = 0;
int ret;

- if (!con->con || !(con->flag & CON_DRIVER_FLAG_MODULE) ||
- con_is_graphics(con->con, con->first, con->last))
+ if (!con->con || !(con->flag & CON_DRIVER_FLAG_MODULE))
goto err;

csw = con->con;
--
2.1.0

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