Re: [PATCH 1/4] RDMA/core: Fix ib_dma_max_seg_size()

[Jason Gunthorpe <jgg@ziepe.ca>]

On Mon, Oct 21, 2019 at 08:03:32AM -0700, Bart Van Assche wrote:
> On 10/21/19 7:09 AM, Jason Gunthorpe wrote:
> > On Sun, Oct 20, 2019 at 07:10:27PM -0700, Bart Van Assche wrote:
> > > diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> > > index 6a47ba85c54c..e6c167d03aae 100644
> > > +++ b/include/rdma/ib_verbs.h
> > > @@ -4043,9 +4043,7 @@ static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
> > >    */
> > >   static inline unsigned int ib_dma_max_seg_size(struct ib_device *dev)
> > >   {
> > > -	struct device_dma_parameters *p = dev->dma_device->dma_parms;
> > > -
> > > -	return p ? p->max_segment_size : UINT_MAX;
> > > +	return dma_get_max_seg_size(dev->dma_device);
> > >   }
> > 
> > Should we get rid of this wrapper?
> 
> Hi Jason,
> 
> In general I agree that getting rid of single line inline functions is good.
> In this case however I'd like to keep the wrapper such that RDMA ULP code
> does not have to deal with the choice between dev->dma_device and &dev->dev.
> From struct ib_device:
>  /* Do not access @dma_device directly from ULP nor from HW drivers. */
> struct device                *dma_device;

Do you think it is a mistake we have dma_device at all?

Can the modern dma framework let us make the 'struct ib_device' into a
full dma_device that is still connected to some PCI device?

Jason