[Xenomai-core] [PATCH 0/4] Fixes and improvements around xnlock

[Jan Kiszka <jan.kiszka@domain.hid>]

Hi,

I'm happy to announce a patch series which actually started like "hey,
let's check if we can have this nice FIFO ticket spinlock algorithm also
for our recursive xnlock." The result is a critical bug fix and a
massive text size reduction of nucleus and skins, both concerning SMP
systems. Furthermore, there are now optional ticket locks available for
larger SMP boxes. :)

This series consists of

 1. Refactoring of asm-generic/system.h
    (+ some optimization of xnlock_get)

 2. SMP-critical memory barrier fix for xnlock_put
    (+ optimization for production code)

 3. Uninlining of xnlock_get_irqsave/xnlock_put_irqrestore on SMP
    (xeno_nucleus text, x86-64, non-debug: 112482 -> 79453 bytes!)

 4. Optional FIFO ticket spinlock for strict deterministic spin times
    on xnlocks (still highly experimental!)

The second patch is stable stuff, so we should merge 1+2 into 2.4.x as well.

Jan