Re: [RFC][PATCH] x86: make text_poke() atomic

Masami Hiramatsu
2009-03-02T23:38:38Z

Ingo Molnar wrote:
>>> So perhaps another approach to (re-)consider would be to go back
>>> to atomic fixmaps here. It spends 3 slots but that's no big
>>> deal.
>> Oh, it's a good idea! fixmaps must make it simpler.
>>
>>> In exchange it will be conceptually simpler, and will also scale
>>> much better than a global spinlock. What do you think?
>> I think even if I use fixmaps, we have to use a spinlock to protect
>> the fixmap area from other threads...
>
> that's why i suggested to use an atomic-kmap, not a fixmap.

Even if the mapping is atomic, text_poke() has to protect pte
from other text_poke()s while changing code.
AFAIK, atomic-kmap itself doesn't ensure that, does it?

Thank you,

>
> Ingo
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--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com