Messages in this thread | | | Date | Wed, 6 Dec 2006 11:25:35 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it |
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On Wed, 6 Dec 2006, Al Viro wrote: > > No. sparc32 doesn't have one, for instance.
Ok. For SMP-safety, it's important that any architecture that can't do this needs to _share_ the same spinlock (on SMP only, of course) that it uses for the bitops.
It would be good (but perhaps not as strict a requirement) if the atomic counters also use the same lock. But that is probably impossible on sparc32 (since it has a per-counter "lock"-like thing, iirc). So doing a cmpxchg() on an atomic_t would be a bug.
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