Messages in this thread | | | Date | Thu, 24 Feb 2022 08:58:36 +0000 | Subject | Re: [PATCH v6 01/11] iommu: Add dma ownership management interfaces | From | Robin Murphy <> |
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On 2022-02-24 05:29, Lu Baolu wrote: > On 2/24/22 1:16 PM, Lu Baolu wrote: >> Hi Robin and Jason, >> >> On 2/24/22 2:02 AM, Jason Gunthorpe wrote: >>> On Wed, Feb 23, 2022 at 06:00:06PM +0000, Robin Murphy wrote: >>> >>>> ...and equivalently just set owner_cnt directly to 0 here. I don't >>>> see a >>>> realistic use-case for any driver to claim the same group more than >>>> once, >>>> and allowing it in the API just feels like opening up various potential >>>> corners for things to get out of sync. >>> I am Ok if we toss it out to get this merged, as there is no in-kernel >>> user right now. >> >> So we don't need the owner pointer in the API anymore, right? > > Oh, NO. > > The owner token represents that the group has been claimed for user > space access. And the default domain auto-attach policy will be changed > accordingly. > > So we still need this. Sorry for the noise.
Exactly. In fact we could almost go the other way, and rename owner_cnt to dma_api_users and make it mutually exclusive with owner being set, but that's really just cosmetic. It's understandable enough as-is that owner_cnt > 0 with owner == NULL represents implicit DMA API ownership.
Cheers, Robin.
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