Re: [PATCH for-rc] RDMA/core: Fix corrupted SL on passive side

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Mar 24, 2021 at 02:34:13PM +0000, Håkon Bugge wrote:
> 
> 
> > On 23 Mar 2021, at 20:46, Jason Gunthorpe <jgg@nvidia.com> wrote:
> > 
> > On Mon, Mar 22, 2021 at 02:35:32PM +0100, Håkon Bugge wrote:
> >> On RoCE systems, a CM REQ contains a Primary Hop Limit > 1 and Primary
> >> Subnet Local is zero.
> >> 
> >> In cm_req_handler(), the cm_process_routed_req() function is
> >> called. Since the Primary Subnet Local value is zero in the request,
> >> and since this is RoCE (Primary Local LID is permissive), the
> >> following statement will be executed:
> >> 
> >>      IBA_SET(CM_REQ_PRIMARY_SL, req_msg, wc->sl);
> >> 
> >> This corrupts SL in req_msg if it was different from zero. In other
> >> words, a request to setup a connection using an SL != zero, will not
> >> be honored, and a connection using SL zero will be created instead.
> >> 
> >> Fixed by not calling cm_process_routed_req() on RoCE systems.
> >> 
> >> Fixes: 3971c9f6dbf2 ("IB/cm: Add interim support for routed paths")
> >> Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
> >> drivers/infiniband/core/cm.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> >> index 3d194bb..6adbaea 100644
> >> +++ b/drivers/infiniband/core/cm.c
> >> @@ -2138,7 +2138,8 @@ static int cm_req_handler(struct cm_work *work)
> >> 		goto destroy;
> >> 	}
> >> 
> >> -	cm_process_routed_req(req_msg, work->mad_recv_wc->wc);
> >> +	if (cm_id_priv->av.ah_attr.type != RDMA_AH_ATTR_TYPE_ROCE)
> >> +		cm_process_routed_req(req_msg, work->mad_recv_wc->wc);
> > 
> > why use ah_attr.type when a few lines below we have:
> > 
> > 	if (gid_attr &&
> > 	    rdma_protocol_roce(work->port->cm_dev->ib_device,
> > 			       work->port->port_num)) {
> > 
> > ?
> > 
> > I suspect you can just move this into the else?
> 
> I can counter that by saying ah_attr.type is used ~10 lines further
> down in the conditional call to sa_path_set_dmac() ;-)

Hum, OK. Please send an additional patch to unify everything around
av.ah_attr.type

> > 	if (gid_attr &&
> > 	    rdma_protocol_roce(work->port->cm_dev->ib_device,
> > 			       work->port->port_num)) {
> 
> I cannot really see how gid_attr could be null. If
> ib_init_ah_attr_from_wc() succeeds, it is set after the call to
> cm_init_av_for_response() above. May be using ah_attr.type in this
> test instead, for uniformity and readability?

The GRH is optional, ib_init_ah_attr_from_wc() only sets it
conditionally.

Applied to for-next

Thanks,
Jason