Re: [Intel-gfx] [PATCH 1/6] dma-buf: add dynamic DMA-buf handling v10

Daniel Vetter
2019-06-24T14:41:05Z

On Mon, Jun 24, 2019 at 03:58:00PM +0200, Christian König wrote:
> Am 24.06.19 um 13:23 schrieb Koenig, Christian:
> > Am 21.06.19 um 18:27 schrieb Daniel Vetter:
> >
> > > So I pondered a few ideas while working out:
> > >
> > > 1) We drop this filtering. Importer needs to keep track of all its
> > > mappings and filter out invalidates that aren't for that specific importer
> > > (either because already invalidated, or not yet mapped, or whatever).
> > > Feels fragile.
> > >
> > > [SNIP]
> > [SNIP]
> >
> > I will take a moment and look into #1 as well, but I still don't see the
> > need to change anything.
>
> That turned out much cleaner than I thought it would be. Essentially it is
> only a single extra line of code in amdgpu.
>
> Going to send that out as a patch set in a minute.

Yeah I mean kinda expected that because:
- everything's protected with ww_mutex anyway
- importer needs to keep track of mappings anways
So really all it needs to do is not be stupid and add the mapping it just
created to its tracking while still holding the ww_mutex. Similar on
invalidate/unmap.

With that all we need is a huge note in the docs that importers need to
keep track of their mappings and dtrt (with all the examples here spelled
out in the appropriate kerneldoc). And then I'm happy :-)

Cheers, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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