On Thu, Aug 31, 2017 at 6:27 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Aug 31, 2017 at 6:01 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>>
>> Ugh, nommu defeats the MAP_SHARED_VALIDATE proposal from Linus.
>>
>> if ((flags & MAP_TYPE) != MAP_PRIVATE &&
>> (flags & MAP_TYPE) != MAP_SHARED)
>> return -EINVAL;
>>
>> ...parisc strikes again.
>
> Why? That's no different from the case statement for the mmu case,
> just written differently.
>
> You *want* existing kernels to fail, since they don't test the bits
> you want to test.
>
> So you just want to rewrite these all as
>
> switch (flags & MAP_TYPE) {
> case MAP_SHARED_VALIDATE:
> .. validate the other bits...
> /* fallhtough */
> case MAP_SHARED:
> .. do the shared case ..
> case MAP_PRIVATE:
> .. do the private case ..
> default:
> return -EINVAL;
> }
>
> and you're all good.
>
> I'm not seeing the problem.
Right, I went cross-eyed for a second. There is no problem.
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