IB/mthca: Safer max_send_sge/max_recv_sge calculation

Calculation of QP capabilities still isn't exactly right in mthca:
max_send_sge/max_recv_sge fields returned in create_qp can exceed the
handware supported limits.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index 5899f0c765be..dd4e13303e96 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -918,10 +918,12 @@ static void mthca_adjust_qp_caps(struct mthca_dev *dev,
         else
                 qp->max_inline_data = max_data_size - MTHCA_INLINE_HEADER_SIZE;
 
-        qp->sq.max_gs = max_data_size / sizeof (struct mthca_data_seg);
-        qp->rq.max_gs = (min(dev->limits.max_desc_sz, 1 << qp->rq.wqe_shift) -
-                        sizeof (struct mthca_next_seg)) /
-                        sizeof (struct mthca_data_seg);
+        qp->sq.max_gs = min_t(int, dev->limits.max_sg,
+                              max_data_size / sizeof (struct mthca_data_seg));
+        qp->rq.max_gs = min_t(int, dev->limits.max_sg,
+                               (min(dev->limits.max_desc_sz, 1 << qp->rq.wqe_shift) -
+                                sizeof (struct mthca_next_seg)) /
+                               sizeof (struct mthca_data_seg));
 }
 
 /*