Re: [PATCH 2/6] dma-resv: Define guards for context-less dma_resv locks

[Boris Brezillon]

On Mon, 18 May 2026 14:18:41 +0200
Christian König <christian.koenig@xxxxxxx> wrote:

> On 5/18/26 11:14, Boris Brezillon wrote:
> > Hi Christian,
> > 
> > On Mon, 18 May 2026 09:10:23 +0200
> > Christian König <christian.koenig@xxxxxxx> wrote:
> >   
> >> On 5/13/26 18:58, Boris Brezillon wrote:  
> >>> When used without a context, dma_resv are no different from regular
> >>> locks. Define guards so we can use the guard-syntactic sugars for
> >>> explicit/implicit scoped locks.
> >>>
> >>> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>    
> >>
> >> Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> >>
> >> How do you want to upstream it? My preference would be drm-misc-next, but I think I can live with a panthor specific branch as well.  
> > 
> > Everything Panthor related goes through drm-misc-next, so drm-misc-next
> > also has my preference ;-). But I'd like to wait for more feedback on
> > the other drm patches, and there are a few things I need to address in
> > the panthor patches anyway, so it's likely to take a couple more weeks
> > for this series to hit the drm-misc tree, unless you have a good reason
> > to fast-track this specific patch.  
> 
> Well the DMA-buf code itself uses dma_resv_lock/unlock

There's no use in dma-resv.c that can be converted to guards. I gave
dma-buf.c a try, but just like for panthor, I don't really like the fact
it's halfway through (other locks still use manual locking), so I'd be
tempted to convert everything at once for consistency. If you're fine
with that, I can give this a try.

> and obviously has test cases for all the different variants.

Looks like the test cases all validate that dma_resv_lock(x, NULL)
returns 0. If I were to convert those to guard(dma_resv)(), these checks
would be gone. Is that okay with you?