[PATCH] vt: Fix replacement console check when unbinding

From: Daniel Vetter
Date: Fri Jun 06 2014 - 05:43:16 EST

I don't fully understand the magic of the vt register/unregister
logic, but apparently everything but the inital console (as set
in the conswitchp pointer) is marked with FLAG_MODULE. Which means
if something unregistered the boot vt driver (e.g. i915.ko kicking
out vga_con) there's nothing left when trying to unbind e.g. fbcon
through sysfs.

But in most cases have the dummy console hanging around besides the
boot console, so this test is fairly dubious. What we actually want is
simply a different console than the one we want to unbind.

v2: Correct the commit message to clarify that the dummy console isn't
always around, but only in most cases (David).

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: David Herrmann <dh.herrmann@xxxxxxxxx>
Reviewed-by: David Herrmann <dh.herrmann@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
drivers/tty/vt/vt.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 3ad0b61e35b4..ea600f482eeb 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3155,8 +3155,7 @@ int do_unbind_con_driver(const struct consw *csw, int first, int last, int deflt
for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
con_back = &registered_con_driver[i];

- if (con_back->con &&
- !(con_back->flag & CON_DRIVER_FLAG_MODULE)) {
+ if (con_back->con && con_back->con != csw) {
defcsw = con_back->con;
retval = 0;

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