syscons - Avoid potential blocking issue.
authorAntonio Huete Jimenez <tuxillo@quantumachine.net>
Tue, 18 Oct 2011 10:09:36 +0000 (12:09 +0200)
committerAntonio Huete Jimenez <tuxillo@quantumachine.net>
Tue, 18 Oct 2011 14:40:20 +0000 (16:40 +0200)
commit55409351f4b3d876298aaa350dcbd97a15123049
tree6d2989aeee4f43d0abe23ae8d787b5ac5a6418f9
parentdb39668bd529972dc154be070b57f398dfe94449
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
sys/dev/misc/syscons/syscons.c