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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.02.16 at 11:08, <quan.xu@xxxxxxxxx> wrote:
>>  On February 26, 2016 4:15pm,  <JBeulich@xxxxxxxx> wrote:
>> >>> On 26.02.16 at 08:37, <quan.xu@xxxxxxxxx> wrote:
>> > On February 25, 2016 8:24pm, <JBeulich@xxxxxxxx> wrote:
>> >> >>> On 25.02.16 at 13:14, <quan.xu@xxxxxxxxx> wrote:
>> >> > On February 25, 2016 4:59pm, <JBeulich@xxxxxxxx> wrote:
>> Nevertheless I'd recommend not mixing things for the pcidevs one, as its uses
>> are scattered around too much for it to be reasonably possible to prove
>> correctness if done that way.
> 
> 
>> Instead please make the lock a static variable in e.g.
>> xen/drivers/pci/pci.c or xen/drivers/passthrough/pci.c, and force
>> acquire/release to go through helper functions. That way we can ensure
>> instance gets left. The only safe alternative to this would be to rename the 
>> lock
>> at once, or to make it read/write one (but then recursion would be allowed 
>> only
>> for the read cases, and aiui you'd need the write variant for your use).
> 
> Jan, sorry, I don't follow this comment. Is it necessary for v6 patch set?

See my other reply just sent.

Jan


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