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| author | Antonino A. Daplas <adaplas@gmail.com> | 2006-06-26 00:27:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-26 09:58:32 -0700 |
| commit | 1c8ce271fe707d26b7bca4e490067fe65694b363 (patch) | |
| tree | 42fc5fa81161065874b9aa751773d15465a8de9b /drivers/char/vt.c | |
| parent | 50ec42edd9784fad6a37b05be03064ea24098db6 (diff) | |
| download | lwn-1c8ce271fe707d26b7bca4e490067fe65694b363.tar.gz lwn-1c8ce271fe707d26b7bca4e490067fe65694b363.zip | |
[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>
Diffstat (limited to 'drivers/char/vt.c')
| -rw-r--r-- | drivers/char/vt.c | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/drivers/char/vt.c b/drivers/char/vt.c index eb27eed48a86..d7ff7fdb6fe3 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 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt) 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 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt) continue; j = i; + if (CON_IS_VISIBLE(vc)) { k = i; save_screen(vc); @@ -2709,10 +2717,8 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt) 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 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt) 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 /* |