64-bit ppc rwsem

[Benjamin Herrenschmidt]

On Mon, 2010-08-23 at 15:18 -0700, David Miller wrote:
> > I've seen drivers in the past do trylocks at interrupt time ... tho
> I
> > agree it sucks.
> 
> Recently there was a thread where this was declared absolutely
> illegal.
> 
> Maybe it was allowed, or sort-of worked before, and that's why it's
> accounted for with IRQ disables in some implementations.  I don't
> know. 

Ok, I'm happy to say it's a big no-no then.

Arnd, do you want to take over the moving to asm-generic and take care
of the spinlock case as well ? I can send Linus the first patch that
changes powerpc to use atomic_long now along with a few other things I
have pending, then you can pickup from there. Or do you want me to
continue pushing my patch as-is and we can look at cleaning up the
spinlock case separately ?

Cheers,
Ben.