On Thu, Jan 30, 2014 at 06:05:33PM +0000, Peter Zijlstra wrote: > On Thu, Jan 30, 2014 at 05:52:12PM +0000, Will Deacon wrote: > > It would be nice if these were default implementations of the unlock, then > > architectures just implement atomic_sub_release how they like. > > Yes, I suppose that makes sense. Last time I proposed the primitive > nobody yelled at me, so I suppose that means people agree :-) If it's useful for these qrwlocks, that's good enough for me! > > One thing worth mentioning: I have a fairly invasive set of changes pending > > for arch/arm64/include/asm/atomic.h, so if you do decide to go with this, > > I'm more than happy to take the sub_release part via the arm64 tree. I guess > > it depends on when this is likely to get merged. > > I suppose it depends on when I get enough courage to do: vim > arch/*/include/asm/atomic*.h :-) Hehe. > There's a few other cleanups I want to do, like today I found > atomic_{set,clear}_mask() instead of the more natural atomic_{or,and}() > functions. Have you looked at the OpenCL atomic intrinsics at all? http://www.khronos.org/registry/cl/sdk/1.2/docs/man/xhtml/atomicFunctions.html There's a good chance that they can be implemented efficiently on any architectures that care about OpenCL. As you've noticed, composing them together can be more efficient on LL/SC-based architectures too. > I also think we can get rid of the {inc,dec} variants of > smp_mb__{before,after}_atomic() since these barriers should be the same > for _all_ atomic ops that do not already imply full mb semantics, and > they're certainly the same for all current inc/dec. Makes sense. > If tomorrow is another slow day and I get through enough of the review > backlog I might just give it a go. > > Anyway, I'll base them on your arm64 changes, I know where to find > those. Okey doke. If you need a stable (non-rebasing) branch, just holler. Cheers, Will -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html