[Xen-devel] question about atomic get_page

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

Now get_page on x86 is implemented to atomic exchange both _domain and
count_info simultaneously. Cmpxchg8b is used to cover two fields because
they are all 32bit width.

However on ia64 where _domain is 64bit, hard to use single instruction
to cover two fields. Yes, there's workaround to solve that, like adding
spinlock with some overhead. But I'd like to know the reason why _domain
and count_info should be operated together. Is there any case that
ownership changes just after checking ownership and before modifying
count_info?

Thanks,
Kevin 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel