request for review: backport of sx and rwlocks from 7.0 to 6-stable

[Alfred Perlstein]

* Kris Kennaway <kris at FreeBSD.org> [070831 01:51] wrote:
> Alfred Perlstein wrote:
> >Hi guys,
> >
> >Some work here at work was approved for sharing with community so
> >I'm posting it here in hope of a review.
> >
> >We run some pretty good stress testing on our code, so I think it's
> >pretty solid.
> >
> >My only concern is that I've tried my best to preserve kernel source
> >API, but not binary compat though a few simple #defines.
> >
> >I can make binary compat, in albeit a somewhat confusing manner, but
> >that will require some rototilling and weird renaming of calls to
> >the sleepq and turnstile code.  In short, I'd rather not, but I will
> >if you think it's something that should be done.
> >
> >There's also a few placeholders for lock profiling which I will
> >very likely be backporting shortly as well.
> >
> >Patch is attached.
> >
> >Comments/questions?
> 
> Hmm, I would be happy to see this but I think binary compatibility is 
> actually important here since this is -stable and low-level primitives 
> like sx are probably used all over the place in existing third party 
> modules.

Ah, yes, sorry, the API stuff is the sleep_queue and turnstile apis, not
the sx api itself.

-Alfred