Messages in this thread | | | Date | Thu, 21 Aug 2008 09:48:09 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4 released |
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On Thu, Aug 21, 2008 at 09:18:29AM -0700, Linus Torvalds wrote: > > > On Thu, 21 Aug 2008, Linus Torvalds wrote: > > > > No, I haven't seen the drafts > > Ok, I have looked at the draft now, and I don't think I was overly > pessimistic. > > If I read it right, all the memory ordering operations are defined for > _single_ objects. So if you want to do the kernel kind of memory ordering > where you specify ordering requirements independently of the actual > accesses (perhaps because the accesses are in some helper function that > doesn't care, but then you want to "finalize" the thing by stating a > sequence point), it seems to be impossible with current drafts.
You are looking for atomic_fence() on page 1168 (1154 virtual) of the most recent draft. The current semantics are not correct, but this is being worked. And yes, it does currently have a variable associated with it, but it acts as a bare fence nevertheless. There is a proposal to drop the variable. As you said in a previous email, design by committee.
> Oh, well. Nothing lost. I didn't expect the thing to work.
;-)
Thanx, Paul
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