git: DragonFly_RELEASE_2_12 syscons - Avoid potential blocking issue.

[Antonio Huete Jimenez <tuxillo@xxxxxxxxxxxxxxxxxxxxxxx>]

commit 55409351f4b3d876298aaa350dcbd97a15123049
Author: Antonio Huete Jimenez <tuxillo@quantumachine.net>
Date:   Tue Oct 18 12:09:36 2011 +0200

    syscons - Avoid potential blocking issue.
    
    - kbd_ioctl() uses it's own locking via lockmgr() and the
      syscons softc is protected using a mutex, so we better
      avoid both locks at once due possible blocking issues.
      In fact, in my particular case the panic only occurs in
      real hardware, while on a VMWare VM I had a lockup.
    - Only found in 4-CPU SMP setups.
    - Discovered via DEBUG_LOCKS option.
    
    DragonFly-bug: <http://bugs.dragonflybsd.org/issue2148>
    Reviewed-by: @dillon, @sjg

Summary of changes:
 sys/dev/misc/syscons/syscons.c |   50 +++++++++++++++++++++++++++------------
 1 files changed, 34 insertions(+), 16 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/55409351f4b3d876298aaa350dcbd97a15123049


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