Re: [Xen-devel] [PATCH v5 5/7] VT-d: Refactor iommu_ops .map_page() and unmap_page()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.02.16 at 13:14, <quan.xu@xxxxxxxxx> wrote:
> On February 25, 2016 4:59pm, <JBeulich@xxxxxxxx> wrote:
>> I'd
>> really suggest investigating alternatives. One that comes to mind would be to
>> move acquiring/releasing pcidevs_lock into a helper function, and setting a
>> per-CPU flag indicating ownership. 
> 
> To me, this might be fine.
> Does Per-CPU flag refer to this_cpu(iommu_dont_flush_iotlb) or variant?

Yes. But I'd prefer ...

>> However, the same effect could be achieved
>> by making the lock a recursive one, which would then seem to more
>> conventional approach (but requiring as much code to be touched).
>> Both approached would eliminate the need to pass down "locked"
>> flags.

... this one (the more that the other won't mean less changes).

Jan


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