[PATCH] drm/gem-cma-helper: Change the level of the allocation failure message

[Boris Brezillon]

On Thu, 5 Oct 2017 09:48:24 +0100
Eric Engestrom <eric.engestrom at imgtec.com> wrote:

> On Wednesday, 2017-10-04 22:28:54 +0000, Eric Anholt wrote:
> > Boris Brezillon <boris.brezillon at free-electrons.com> writes:
> >   
> > > drm_gem_cma_create() prints an error message when dma_alloc_wc() fails to
> > > allocate the amount of memory we requested. This can lead to annoying
> > > error messages when CMA is only one possible source of memory for the BO
> > > allocation.
> > >
> > > Turn this error message into a debug one and add a __must_check specifier
> > > to make sure all callers are checking the return value.
> > >
> > > Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>  
> > 
> > The __must_check seems unnecessary to me -- you're definitely going to
> > be doing something with the return value, because otherwise why did you
> > call the object allocate function?  
> 
> Indeed, `__must_check` (aka `warn_unused_result`) only makes sure the
> return value is not discarded, which will probably always be true here.

I agree, this __must_check is not really useful here.

> 
> > The `warn_unused_result` attribute causes a warning to be emitted if
> > a caller of the function with this attribute does not use its return
> > value.  
> 
> I think we need a sparse attribute to check that the return value is
> IS_ERR()-checked?

Can we just turn the dev_err() into dev_dbg() for now? The 'force
callers to check IS_ERR()' is kind of orthogonal to the change I'm
doing here.

> (not volunteering, I have no idea how to add a sparse attribute :)