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fbcon: only unbind from console if successfully registered 

Attempting to unload a framebuffer module calls unregister_framebuffer()
which in turn gets fbcon to release it.  If fbcon has no framebuffers
linked to a console, it will also unbind itself from the console driver.
However, if fbcon never registered itself as a console driver, the unbind
will fail causing the framebuffer device entry to persist.  In most cases
this failure will result in an oops when attempting to access the now
non-existent device.

This patch ensures that the fbcon unbind request will succeed even if a
bind was never done.  It tracks if a successful bind ever occurred & will
only attempt to unbind if needed.  If there never was a bind, it simply
returns with no error.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Ian Armstrong 2009-09-22 16:47:52 -07:00 committed by Linus Torvalds
parent a690606d1f
commit 2ddce3fd0a
1 changed files with 10 additions and 0 deletions
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10
drivers/video/console/fbcon.c
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@ -114,6 +114,7 @@ static int last_fb_vc = MAX_NR_CONSOLES - 1;
static int fbcon_is_default = 1;
static int fbcon_has_exited;
static int primary_device = -1;
static int fbcon_has_console_bind;
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY
static int map_override;
@ -544,6 +545,8 @@ static int fbcon_takeover(int show_logo)
con2fb_map[i] = -1;
}
info_idx = -1;
} else {
fbcon_has_console_bind = 1;
}
return err;
@ -2949,6 +2952,10 @@ static int fbcon_unbind(void)
ret = unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
fbcon_is_default);
if (!ret)
fbcon_has_console_bind = 0;
return ret;
}
#else
@ -2962,6 +2969,9 @@ static int fbcon_fb_unbind(int idx)
{
int i, new_idx = -1, ret = 0;
if (!fbcon_has_console_bind)
return 0;
for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map[i] != idx &&
con2fb_map[i] != -1) {