[patch 0/4] Allow inlined spinlocks again V2

[Heiko Carstens <heiko.carstens@de.ibm.com>]

This patch set allows to have inlined spinlocks again.

V2: rewritten from scratch - now with readable code

The rationale behind this is that function calls on at least s390 are
expensive.

If one considers that server kernels are usually compiled with
!CONFIG_PREEMPT a simple spin_lock is just a compare and swap loop.
The extra overhead for a function call is significant.
With inlined spinlocks overall cpu usage gets reduced by 1%-5% on s390.
These numbers were taken with some network benchmarks. However I expect
any workload that calls frequently into the kernel and which grabs a few
locks to perform better.

The implementation is straight forward: move the function bodies of the
locking functions to static inline functions and place them in a header
file.
Dependent on CONFIG_SPINLOCK_INLINE generate out-of-line or inlined
locking functions.

The patches should be self explaining.