RDMA/mlx4: Ensure that maximal send/receive SGE less than supported by HW

In calculating the global maximum number of the Scatter/Gather elements
supported, the following four maximum parameters must be taken into
consideration: max_sg_rq, max_sg_sq, max_desc_sz_rq and max_desc_sz_sq.

However instead of bringing this complexity to query_device, which still
won't be sufficient anyway (the calculations are dependent on QP type),
the safer approach will be to restore old code, which will give us 32
SGEs.

Fixes: 33023fb85a42 ("IB/core: add max_send_sge and max_recv_sge attributes")
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index ca0f1ee..0bbeaaa 100644 (file)
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -517,9 +517,11 @@ static int mlx4_ib_query_device(struct ib_device *ibdev,
        props->page_size_cap       = dev->dev->caps.page_size_cap;
        props->max_qp              = dev->dev->quotas.qp;
        props->max_qp_wr           = dev->dev->caps.max_wqes - MLX4_IB_SQ_MAX_SPARE;
-       props->max_send_sge        = dev->dev->caps.max_sq_sg;
-       props->max_recv_sge        = dev->dev->caps.max_rq_sg;
-       props->max_sge_rd          = MLX4_MAX_SGE_RD;
+       props->max_send_sge =
+               min(dev->dev->caps.max_sq_sg, dev->dev->caps.max_rq_sg);
+       props->max_recv_sge =
+               min(dev->dev->caps.max_sq_sg, dev->dev->caps.max_rq_sg);
+       props->max_sge_rd = MLX4_MAX_SGE_RD;
        props->max_cq              = dev->dev->quotas.cq;
        props->max_cqe             = dev->dev->caps.max_cqes;
        props->max_mr              = dev->dev->quotas.mpt;