realtime-preempt for MIPS - compile problem with rwsem

["Ryan McAvoy" <ryan.sed@gmail.com>]

Hello,

I have been trying to get the realtime-preempt patches working on a
MIPs processor with the 2.6.15 (and subsequently the 2.6.16) kernel.

One problem I am having is as follows:

- The mips configuration specifically disables
CONFIG_RWSEM_GENERIC_SPINLOCK when CONFIG_PREEMPT_RT is on
- This causes the include/asm-mips/rwsem.h to be included by
include/linux/rwsem.h.
- include/asm-mips/rwsem.h calls rwsem_down_read_failed which is
implemented in lib/rwsem.c
- rwsem.c is only compiled if CONFIG_RWSEM_XCHGADD_ALGORITHM is on.
This option is also disabled if CONFIG_PREEMPT_RT is on.

To summarise, if CONFIG_PREEMPT_RT is on, then the mips specific
rwsem.h is included, but at the same time, it prevents inclusion of
lib/rwsem.c which is needed by the mips rwsem.h.

Does anyone have a solution to this.
Thanks,
Ryan McAvoy