Re: [PATCH] drm: Use idr_init_base(1) when using id==0 for invalid

Daniel Vetter
2018-02-19T14:50:00Z

On Mon, Feb 19, 2018 at 02:35:38PM +0000, Chris Wilson wrote:
> Quoting Christian König (2018-02-13 13:48:24)
> > Am 12.02.2018 um 18:14 schrieb Ville Syrjälä:
> > > On Mon, Feb 12, 2018 at 02:55:33PM +0000, Chris Wilson wrote:
> > >> Use the new idr_init_base() function to create an IDR that knows id==0
> > >> is never allocated as it maps to an invalid identifier. By knowing that
> > >> id==0 is invalid, the IDR can start from id=1 instead avoiding the issue
> > >> of having to start each lookup from the zeroth leaf as id==0 is always
> > >> unused (and thus the tree-of-bitmaps indicate that is the first
> > >> available).
> > >>
> > >> References: 6ce711f27500 ("idr: Make 1-based IDRs more efficient")
> > >> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > >> Cc: Christian Konig <christian.koenig@amd.com>
> > >> Cc: Dave Airlie <airlied@redhat.com>
> > > Yep, looks like all of these pass start==1 to idr_alloc().
> > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Acked-by: Christian König <christian.koenig@amd.com> as well.
> >
> > Probably going to do this for the command submission context handles in
> > amdgpu as well.
>
> Thanks for the review, pushed to drm-misc-next.
>
> As noted, there are probably quite a few more idr's that we can move
> over to idr_init_base(1), e.g. the KMS objects. If someone feels like a
> small task?

I'll type a todo.rst patch.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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