* Peter Zijlstra [off-list ref] wrote:

quoted

It might even be that this is the defined semantics of spin_unlock_wait().

As is, spin_unlock_wait() is somewhat ill defined. IIRC it grew from an 
optimization by Oleg and subsequently got used elsewhere. And it being the 
subtle bugger it is, there were bugs.

I believe the historical, original spin_unlock_wait() came from early SMP 
optimizations of the networking code - and then spread elsewhere, step by step. 
All but one of the networking uses went away since then - so I don't think there's 
any original usecase left.

Thanks,

	Ingo