Eric Lee / linux-smarc-t335x-v3.2

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Commit 2ddce3fd0acbdc1be684fb5f919ae3d2e9518aac

Authored by Ian Armstrong
Committed by Linus Torvalds
1 parent a690606d1f
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

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>

Showing 1 changed file with 10 additions and 0 deletions Side-by-side Diff

drivers/video/console/fbcon.c
Diff comments   View file @ 2ddce3f
... ... @@ -114,6 +114,7 @@
114 114 static int fbcon_is_default = 1;
115 115 static int fbcon_has_exited;
116 116 static int primary_device = -1;
  117 +static int fbcon_has_console_bind;
117 118  
118 119 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY
119 120 static int map_override;
... ... @@ -544,6 +545,8 @@
544 545 con2fb_map[i] = -1;
545 546 }
546 547 info_idx = -1;
  548 + } else {
  549 + fbcon_has_console_bind = 1;
547 550 }
548 551  
549 552 return err;
... ... @@ -2949,6 +2952,10 @@
2949 2952  
2950 2953 ret = unbind_con_driver(&fb_con, first_fb_vc, last_fb_vc,
2951 2954 fbcon_is_default);
  2955 +
  2956 + if (!ret)
  2957 + fbcon_has_console_bind = 0;
  2958 +
2952 2959 return ret;
2953 2960 }
2954 2961 #else
... ... @@ -2961,6 +2968,9 @@
2961 2968 static int fbcon_fb_unbind(int idx)
2962 2969 {
2963 2970 int i, new_idx = -1, ret = 0;
  2971 +
  2972 + if (!fbcon_has_console_bind)
  2973 + return 0;
2964 2974  
2965 2975 for (i = first_fb_vc; i <= last_fb_vc; i++) {
2966 2976 if (con2fb_map[i] != idx &&