Re: linux-2.5.18: DRM + cmpxchg issues

[Keith Whitwell]

george anzinger wrote:
> Keith Whitwell wrote:
> 
>>Adam,
>>
>>I expect the answer is that we need to dig out the old one.
>>
>>Previously I don't think the full cmpxchg semantics werere required unless the
>>box is smp -- there's no case where atomic operations are required for
>>hardware interaction, for example.  ...
>>
>>Probably this changed with preempt, though, so we need one even on UP boxes...
>>
>>
> I can not think of any reason to need a lock or atomic
> operation because of preempt.  Even the management of the
> preempt on/off flags at most requires memory barriers, even
> in SMP boxen.  Do you have an example?

No, I was just pointing out grey areas in my own knowledge.

Keith