[PATCH] Detaching fbcon: fix give_up_console()
To allow for detaching fbcon, it must be able to give up the console.
However, the function give_up_console() is plain broken. It just sets the
entries in the console driver map to NULL, it leaves the vt layer without a
console driver, and does not decrement the module reference count. Calling
give_up_console() is guaranteed to hang the machine..
To fix this problem, ensure that the virtual consoles are not left dangling
without a driver. All systems have a default boot driver (either vgacon or
dummycon) which is never unloaded. For those vt's that lost their driver, the
default boot driver is reassigned back to them.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index eb27eed..d7ff7fd 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -100,6 +100,7 @@
const struct consw *conswitchp;
+static struct consw *defcsw; /* default console */
/* A bitmap for codes <32. A bit of 1 indicates that the code
* corresponding to that bit number invokes some special action
@@ -2673,17 +2674,23 @@
if (!try_module_get(owner))
return -ENODEV;
- acquire_console_sem();
+ /* save default console, for possible recovery later on */
+ if (!defcsw)
+ defcsw = (struct consw *) conswitchp;
+ acquire_console_sem();
desc = csw->con_startup();
+
if (!desc) {
release_console_sem();
module_put(owner);
return -ENODEV;
}
+
if (deflt) {
if (conswitchp)
module_put(conswitchp->owner);
+
__module_get(owner);
conswitchp = csw;
}
@@ -2701,6 +2708,7 @@
continue;
j = i;
+
if (CON_IS_VISIBLE(vc)) {
k = i;
save_screen(vc);
@@ -2709,10 +2717,8 @@
old_was_color = vc->vc_can_do_color;
vc->vc_sw->con_deinit(vc);
vc->vc_origin = (unsigned long)vc->vc_screenbuf;
- vc->vc_visible_origin = vc->vc_origin;
- vc->vc_scr_end = vc->vc_origin + vc->vc_screenbuf_size;
- vc->vc_pos = vc->vc_origin + vc->vc_size_row * vc->vc_y + 2 * vc->vc_x;
visual_init(vc, i, 0);
+ set_origin(vc);
update_attr(vc);
/* If the console changed between mono <-> color, then
@@ -2741,22 +2747,29 @@
printk("to %s\n", desc);
release_console_sem();
-
module_put(owner);
return 0;
}
void give_up_console(const struct consw *csw)
{
- int i;
+ int i, first = -1, last = -1, deflt = 0;
- for(i = 0; i < MAX_NR_CONSOLES; i++)
+ for (i = 0; i < MAX_NR_CONSOLES; i++)
if (con_driver_map[i] == csw) {
+ if (first == -1)
+ first = i;
+ last = i;
module_put(csw->owner);
con_driver_map[i] = NULL;
}
-}
+ if (first != -1 && defcsw) {
+ if (first == 0 && last == MAX_NR_CONSOLES - 1)
+ deflt = 1;
+ take_over_console(defcsw, first, last, deflt);
+ }
+}
#endif
/*