[IB/mthca]: Fix error CQ entry handling on mem-free HCAs

Fix handling of error CQ entries on mem-free HCAs: the doorbell count
is never valid so we shouldn't look at it.  This fixes problems exposed
by new HCA firmware.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_cq.c b/drivers/infiniband/hw/mthca/mthca_cq.c
index b5aea7b869f6..5687c3014522 100644
--- a/drivers/infiniband/hw/mthca/mthca_cq.c
+++ b/drivers/infiniband/hw/mthca/mthca_cq.c
@@ -373,8 +373,12 @@ static int handle_error_cqe(struct mthca_dev *dev, struct mthca_cq *cq,
          * If we're at the end of the WQE chain, or we've used up our
          * doorbell count, free the CQE.  Otherwise just update it for
          * the next poll operation.
+         *
+         * This does not apply to mem-free HCAs: they don't use the
+         * doorbell count field, and so we should always free the CQE.
          */
-        if (!(new_wqe & cpu_to_be32(0x3f)) || (!cqe->db_cnt && dbd))
+        if (mthca_is_memfree(dev) ||
+            !(new_wqe & cpu_to_be32(0x3f)) || (!cqe->db_cnt && dbd))
                 return 0;
 
         cqe->db_cnt   = cpu_to_be16(be16_to_cpu(cqe->db_cnt) - dbd);