Re: [PATCH rdma-next v1 2/4] RDMA: Clean MW allocation and free flows

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Jul 07, 2020 at 07:42:03AM +0300, Leon Romanovsky wrote:
> On Mon, Jul 06, 2020 at 08:04:16PM -0300, Jason Gunthorpe wrote:
> > On Tue, Jun 30, 2020 at 01:18:53PM +0300, Leon Romanovsky wrote:
> > > @@ -916,21 +916,24 @@ static int ib_uverbs_alloc_mw(struct uverbs_attr_bundle *attrs)
> > >  		goto err_put;
> > >  	}
> > >
> > > -	mw = pd->device->ops.alloc_mw(pd, cmd.mw_type, &attrs->driver_udata);
> > > -	if (IS_ERR(mw)) {
> > > -		ret = PTR_ERR(mw);
> > > +	mw = rdma_zalloc_drv_obj(ib_dev, ib_mw);
> > > +	if (!mw) {
> > > +		ret = -ENOMEM;
> > >  		goto err_put;
> > >  	}
> > >
> > > -	mw->device  = pd->device;
> > > -	mw->pd      = pd;
> > > +	mw->device = ib_dev;
> > > +	mw->pd = pd;
> > >  	mw->uobject = uobj;
> > > -	atomic_inc(&pd->usecnt);
> > > -
> > >  	uobj->object = mw;
> > > +	mw->type = cmd.mw_type;
> > >
> > > -	memset(&resp, 0, sizeof(resp));
> > > -	resp.rkey      = mw->rkey;
> > > +	ret = pd->device->ops.alloc_mw(mw, &mw->rkey, &attrs->driver_udata);
> >
> > Why the strange &mw->rkey ? Can't the drivers just do mw->rkey = foo ?
> 
> We can, if we want to allow drivers set fields in ib_* structures that
> there passed as part of alloc_* flows.

This is better than passing weird loose pointers around

Jason