Re: [PATCH rdma-next v1 13/13] RDMA/restrack: Drop valid restrack field as source of ambiguity

[Leon Romanovsky <leon@kernel.org>]

On Sun, Sep 06, 2020 at 11:28:15AM -0300, Jason Gunthorpe wrote:
> On Sun, Sep 06, 2020 at 05:24:00PM +0300, Leon Romanovsky wrote:
> > On Thu, Sep 03, 2020 at 01:21:48PM -0300, Jason Gunthorpe wrote:
> > > On Sun, Aug 30, 2020 at 01:14:36PM +0300, Leon Romanovsky wrote:
> > > > From: Leon Romanovsky <leonro@mellanox.com>
> > > >
> > > > The valid field was needed to distinguish between supported/not
> > > > supported QPs, after the create_qp was changed to support all types,
> > > > that field can be dropped and the code simplified a little bit.
> > > >
> > > > Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
> > > >  drivers/infiniband/core/restrack.c | 29 ++++++++---------------------
> > > >  include/rdma/restrack.h            |  9 ---------
> > > >  2 files changed, 8 insertions(+), 30 deletions(-)
> > > >
> > > > diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
> > > > index 4caaa6312105..fb5345c8bd89 100644
> > > > +++ b/drivers/infiniband/core/restrack.c
> > > > @@ -143,7 +143,7 @@ static struct ib_device *res_to_dev(struct rdma_restrack_entry *res)
> > > >  		return container_of(res, struct rdma_counter, res)->device;
> > > >  	default:
> > > >  		WARN_ONCE(true, "Wrong resource tracking type %u\n", res->type);
> > > > -		return NULL;
> > > > +		return ERR_PTR(-EINVAL);
> > > >  	}
> > > >  }
> > > >
> > > > @@ -223,7 +223,7 @@ int __must_check rdma_restrack_add(struct rdma_restrack_entry *res)
> > > >  	struct rdma_restrack_root *rt;
> > > >  	int ret = 0;
> > > >
> > > > -	if (!dev)
> > > > +	if (IS_ERR_OR_NULL(dev))
> > > >  		return -ENODEV;
> > > >
> > > >  	if (res->no_track)
> > > > @@ -261,10 +261,7 @@ int __must_check rdma_restrack_add(struct rdma_restrack_entry *res)
> > > >  	}
> > > >
> > > >  out:
> > > > -	if (ret)
> > > > -		return ret;
> > > > -	res->valid = true;
> > > > -	return 0;
> > > > +	return ret;
> > > >  }
> > > >  EXPORT_SYMBOL(rdma_restrack_add);
> > > >
> > > > @@ -323,25 +320,16 @@ EXPORT_SYMBOL(rdma_restrack_put);
> > > >   */
> > > >  void rdma_restrack_del(struct rdma_restrack_entry *res)
> > > >  {
> > > > +	struct ib_device *dev = res_to_dev(res);
> > > >  	struct rdma_restrack_entry *old;
> > > >  	struct rdma_restrack_root *rt;
> > > > -	struct ib_device *dev;
> > > >
> > > > -	if (!res->valid) {
> > > > -		if (res->task) {
> > > > -			put_task_struct(res->task);
> > > > -			res->task = NULL;
> > > > -		}
> > > > -		return;
> > > > -	}
> > > > -
> > > > -	if (res->no_track)
> > > > +	WARN_ONCE(!dev && res->type != RDMA_RESTRACK_CM_ID,
> > > > +		  "IB device should be set for restrack type %s",
> > > > +		  type2str(res->type));
> > > > +	if (res->no_track || IS_ERR_OR_NULL(dev))
> > > >  		goto out;
> > > >
> > > > -	dev = res_to_dev(res);
> > > > -	if (WARN_ON(!dev))
> > > > -		return;
> > > > -
> > > >  	rt = &dev->res[res->type];
> > > >  	old = xa_erase(&rt->xa, res->id);
> > >
> > > How does this work without valid?
> > >
> > > xa_alloc is called in rdma_restrack_add() and previously it was safe
> > > to call res_track_del() on unadded things.
> > >
> > > Now there are problems, like __ib_alloc_cq_user() does calls
> > > restrack_del without doing restrack_ad()
> >
> > Maybe I missed it, but I don't see it in the code.
>
> Look at the error unwinding

After this series I will call to rdma_restrack_put() and not to rdma_restrack_del().
in error unwind.

Thanks

>
> Jason