Re: [PATCH for-rc] RDMA/cma: Revert INIT-INIT patch

[Haakon Bugge <haakon.bugge@oracle.com>]

> On 29 Jul 2021, at 20:26, mike.marciniszyn@cornelisnetworks.com wrote:
> 
> From: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
> 
> The net/sunrpc/xprtrdma module creates its QP using rdma_create_qp() and
> immediately post receives, implicitly assuming the QP is in the INIT
> state and thus valid for ib_post_recv().
> 
> The patch noted in Fixes: removed the RESET->INIT modifiy from
> rdma_create_qp(), breaking NFS rdma for verbs providers that fail the
> ib_post_recv() for a bad state.
> 
> This situation was proven using kprobes in rvt_post_recv() and
> rvt_modify_qp(). The traces showed that the rvt_post_recv() failed before
> ANY modify QP and that the current state was RESET.
> 
> Fix by reverting the patch below.
> 
> Fixes: dc70f7c3ed34 ("RDMA/cma: Remove unnecessary INIT->INIT transition")
> Cc: Haakon Bugge <haakon.bugge@oracle.com>
> Cc: Chuck Lever III <chuck.lever@oracle.com>
> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>

Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>


Thxs, Håkon

> ---
> drivers/infiniband/core/cma.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 515a7e9..5d3b8b8 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -926,12 +926,25 @@ static int cma_init_ud_qp(struct rdma_id_private *id_priv, struct ib_qp *qp)
> 	return ret;
> }
> 
> +static int cma_init_conn_qp(struct rdma_id_private *id_priv, struct ib_qp *qp)
> +{
> +	struct ib_qp_attr qp_attr;
> +	int qp_attr_mask, ret;
> +
> +	qp_attr.qp_state = IB_QPS_INIT;
> +	ret = rdma_init_qp_attr(&id_priv->id, &qp_attr, &qp_attr_mask);
> +	if (ret)
> +		return ret;
> +
> +	return ib_modify_qp(qp, &qp_attr, qp_attr_mask);
> +}
> +
> int rdma_create_qp(struct rdma_cm_id *id, struct ib_pd *pd,
> 		   struct ib_qp_init_attr *qp_init_attr)
> {
> 	struct rdma_id_private *id_priv;
> 	struct ib_qp *qp;
> -	int ret = 0;
> +	int ret;
> 
> 	id_priv = container_of(id, struct rdma_id_private, id);
> 	if (id->device != pd->device) {
> @@ -948,6 +961,8 @@ int rdma_create_qp(struct rdma_cm_id *id, struct ib_pd *pd,
> 
> 	if (id->qp_type == IB_QPT_UD)
> 		ret = cma_init_ud_qp(id_priv, qp);
> +	else
> +		ret = cma_init_conn_qp(id_priv, qp);
> 	if (ret)
> 		goto out_destroy;
> 
> -- 
> 1.8.3.1
>