Re: [PATCH rdma-rc] RDMA/cma: Limit join multicast to UD QP type only

[Leon Romanovsky <leon@kernel.org>]

On Fri, Apr 08, 2022 at 03:24:40PM -0300, Jason Gunthorpe wrote:
> On Mon, Apr 04, 2022 at 05:52:18PM +0300, Leon Romanovsky wrote:
> > -static int cma_set_qkey(struct rdma_id_private *id_priv, u32 qkey)
> > +static int cma_set_default_qkey(struct rdma_id_private *id_priv)
> >  {
> >  	struct ib_sa_mcmember_rec rec;
> >  	int ret = 0;
> >  
> > -	if (id_priv->qkey) {
> > -		if (qkey && id_priv->qkey != qkey)
> > -			return -EINVAL;
> > -		return 0;
> > -	}
> > -
> > -	if (qkey) {
> > -		id_priv->qkey = qkey;
> > -		return 0;
> > -	}
> > -
> >  	switch (id_priv->id.ps) {
> >  	case RDMA_PS_UDP:
> >  	case RDMA_PS_IB:
> > @@ -528,9 +517,22 @@ static int cma_set_qkey(struct rdma_id_private *id_priv, u32 qkey)
> >  	default:
> >  		break;
> >  	}
> > +
> >  	return ret;
> >  }
> >  
> > +static int cma_set_qkey(struct rdma_id_private *id_priv, u32 qkey)
> > +{
> > +	if (!qkey)
> > +		return cma_set_default_qkey(id_priv);
> 
> This should be called in the couple of places that are actually
> allowed to set a default qkey. We have some confusion about when that
> is supposed to happen and when a 0 qkey can be presented.
> 
> But isn't this not the same? The original behavior was to make the
> set_default a NOP if the id_priv already had a qkey:
> 
>  -	if (id_priv->qkey) {
>  -		if (qkey && id_priv->qkey != qkey)
> 
> But that is gone now?

When I reviewed, I got an impression what once we create id_priv and set
qkey to default values, we won't hit this if (..).

> 
> I got this:
> 
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 3e315fc0ac16cb..ef980ea7153e51 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -1102,7 +1102,7 @@ static int cma_ib_init_qp_attr(struct rdma_id_private *id_priv,
>  	*qp_attr_mask = IB_QP_STATE | IB_QP_PKEY_INDEX | IB_QP_PORT;
>  
>  	if (id_priv->id.qp_type == IB_QPT_UD) {
> -		ret = cma_set_qkey(id_priv, 0);
> +		ret = cma_set_default_qkey(id_priv);

This is ok

>  		if (ret)
>  			return ret;
>  
> @@ -4430,14 +4430,10 @@ int rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param)
>  
>  	if (rdma_cap_ib_cm(id->device, id->port_num)) {
>  		if (id->qp_type == IB_QPT_UD) {
> -			if (conn_param)
> -				ret = cma_send_sidr_rep(id_priv, IB_SIDR_SUCCESS,
> -							conn_param->qkey,
> -							conn_param->private_data,
> -							conn_param->private_data_len);
> -			else
> -				ret = cma_send_sidr_rep(id_priv, IB_SIDR_SUCCESS,
> -							0, NULL, 0);
> +			ret = cma_send_sidr_rep(id_priv, IB_SIDR_SUCCESS,
> +						conn_param->qkey,
> +						conn_param->private_data,
> +						conn_param->private_data_len);

It is ok too and we have many other places with not-possible "if (conn_param)".

>  		} else {
>  			if (conn_param)
>  				ret = cma_accept_ib(id_priv, conn_param);
> @@ -4685,7 +4681,7 @@ static int cma_join_ib_multicast(struct rdma_id_private *id_priv,
>  	if (ret)
>  		return ret;
>  
> -	ret = cma_set_qkey(id_priv, 0);
> +	ret = cma_set_default_qkey(id_priv);
>  	if (ret)
>  		return ret;
>  
> 
> >  static void cma_translate_ib(struct sockaddr_ib *sib, struct rdma_dev_addr *dev_addr)
> >  {
> >  	dev_addr->dev_type = ARPHRD_INFINIBAND;
> > @@ -4762,8 +4764,7 @@ static int cma_iboe_join_multicast(struct rdma_id_private *id_priv,
> >  	cma_iboe_set_mgid(addr, &ib.rec.mgid, gid_type);
> >  
> >  	ib.rec.pkey = cpu_to_be16(0xffff);
> > -	if (id_priv->id.ps == RDMA_PS_UDP)
> > -		ib.rec.qkey = cpu_to_be32(RDMA_UDP_QKEY);
> > +	ib.rec.qkey = cpu_to_be32(RDMA_UDP_QKEY);
> 
> Why isn't this symetrical with the IB side:
> 
> 	ret = cma_set_default_qkey(id_priv);
> 	if (ret)
> 		return ret;
> 	rec.qkey = cpu_to_be32(id_priv->qkey);
> 
> 
> ??

The original code didn't touch id_priv.

> 
> It fells like set_default_qkey() is the right thing to do incase the
> qkey was already set by something, just as IB does it.
> 
> > @@ -4815,6 +4816,9 @@ int rdma_join_multicast(struct rdma_cm_id *id, struct sockaddr *addr,
> >  			    READ_ONCE(id_priv->state) != RDMA_CM_ADDR_RESOLVED))
> >  		return -EINVAL;
> >  
> > +	if (id_priv->id.qp_type != IB_QPT_UD)
> > +		return -EINVAL;
> > +
> 
> This makes sense
> 
> Jason