IB: Change CQE "csum_ok" field to a bit flag

Use a bit in wc_flags rather then a whole integer to hold the
"checksum OK" flag.  By itself, this change doesn't reduce the size of
struct ib_wc on 64bit machines -- it stays on 56 bytes because of
padding.  However, it will allow to add more fields in the future
without enlarging the struct.  Also, it will let us have a unified
approach with future libibverbs checksum offload reporting, because a
bit flag doesn't break the library ABI.

This patch was suggested during conversation with Liran Liss
<liranl@mellanox.com>.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

6 files changed, 7 insertions, 6 deletions

diff --git a/drivers/infiniband/hw/mlx4/cq.c b/drivers/infiniband/hw/mlx4/cq.c
index 5ecf38d97269..09eb1d19e72d 100644
--- a/drivers/infiniband/hw/mlx4/cq.c
+++ b/drivers/infiniband/hw/mlx4/cq.c
@@ -720,7 +720,8 @@ repoll:
                 wc->dlid_path_bits = (g_mlpath_rqpn >> 24) & 0x7f;
                 wc->wc_flags      |= g_mlpath_rqpn & 0x80000000 ? IB_WC_GRH : 0;
                 wc->pkey_index     = be32_to_cpu(cqe->immed_rss_invalid) & 0x7f;
-                wc->csum_ok        = mlx4_ib_ipoib_csum_ok(cqe->status, cqe->checksum);
+                wc->wc_flags      |= mlx4_ib_ipoib_csum_ok(cqe->status,
+                                        cqe->checksum) ? IB_WC_IP_CSUM_OK : 0;
                 if (rdma_port_get_link_layer(wc->qp->device,
                                 (*cur_qp)->port) == IB_LINK_LAYER_ETHERNET)
                         wc->sl  = be16_to_cpu(cqe->sl_vid) >> 13;
diff --git a/drivers/infiniband/hw/mthca/mthca_cq.c b/drivers/infiniband/hw/mthca/mthca_cq.c
index 53157b86a1ba..40ba83338155 100644
--- a/drivers/infiniband/hw/mthca/mthca_cq.c
+++ b/drivers/infiniband/hw/mthca/mthca_cq.c
@@ -643,7 +643,8 @@ static inline int mthca_poll_one(struct mthca_dev *dev,
                 entry->wc_flags   |= cqe->g_mlpath & 0x80 ? IB_WC_GRH : 0;
                 checksum = (be32_to_cpu(cqe->rqpn) >> 24) |
                                 ((be32_to_cpu(cqe->my_ee) >> 16) & 0xff00);
-                entry->csum_ok = (cqe->sl_ipok & 1 && checksum == 0xffff);
+                entry->wc_flags   |=  (cqe->sl_ipok & 1 && checksum == 0xffff) ?
+                                                        IB_WC_IP_CSUM_OK : 0;
         }
 
         entry->status = IB_WC_SUCCESS;
diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 894afac26f3b..765b4cbaa020 100644
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -2048,7 +2048,6 @@ send_last:
                 wc.pkey_index = 0;
                 wc.dlid_path_bits = 0;
                 wc.port_num = 0;
-                wc.csum_ok = 0;
                 /* Signal completion event if the solicited bit is set. */
                 qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
                              (ohdr->bth[0] &
diff --git a/drivers/infiniband/hw/qib/qib_uc.c b/drivers/infiniband/hw/qib/qib_uc.c
index 847e7afdfd94..7ce2ac2ed219 100644
--- a/drivers/infiniband/hw/qib/qib_uc.c
+++ b/drivers/infiniband/hw/qib/qib_uc.c
@@ -422,7 +422,6 @@ last_imm:
                 wc.pkey_index = 0;
                 wc.dlid_path_bits = 0;
                 wc.port_num = 0;
-                wc.csum_ok = 0;
                 /* Signal completion event if the solicited bit is set. */
                 qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
                              (ohdr->bth[0] &
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index 4115be54ba3b..5c1bc995e560 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -296,7 +296,8 @@ static void ipoib_ib_handle_rx_wc(struct net_device *dev, struct ib_wc *wc)
         dev->stats.rx_bytes += skb->len;
 
         skb->dev = dev;
-        if ((dev->features & NETIF_F_RXCSUM) && likely(wc->csum_ok))
+        if ((dev->features & NETIF_F_RXCSUM) &&
+                        likely(wc->wc_flags & IB_WC_IP_CSUM_OK))
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 
         napi_gro_receive(&priv->napi, skb);
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index ff22a73e0937..c3cca5a4dacd 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -518,6 +518,7 @@ enum ib_wc_flags {
         IB_WC_GRH               = 1,
         IB_WC_WITH_IMM          = (1<<1),
         IB_WC_WITH_INVALIDATE   = (1<<2),
+        IB_WC_IP_CSUM_OK        = (1<<3),
 };
 
 struct ib_wc {
@@ -538,7 +539,6 @@ struct ib_wc {
         u8                      sl;
         u8                      dlid_path_bits;
         u8                      port_num;       /* valid only for DR SMPs on switches */
-        int                     csum_ok;
 };
 
 enum ib_cq_notify_flags {