>  >     It sounds nice to make them inline, but why not <arm/atomic.h>?  
> 
> Well, sure, and each arm platform would provide <machine/atomic.h> that
> simply included it.

Let's be careful not to loose the out-of-line copies though.  I might want 
to start experimenting with a kernel that is substantially Thumb code at 
some point, and in that case atomic operations will probably have to be in 
a function call ('cos instructions like SWP don't exist in Thumb code).

R.