IB: Return qp pointer as part of ib_wc

struct ib_wc currently only includes the local QP number: this matches
the IB spec, but seems mostly useless. The following patch replaces
this with the pointer to qp itself, and updates all low level drivers
and all users.

This has the following advantages:
- Ability to get a per-qp context through wc->qp->qp_context
- Existing drivers already have the qp pointer ready in poll cq, so
  this change actually saves a tiny bit (extra memory read) on data path
  (for ehca it would actually be expensive to find the QP pointer when
  polling a CQ, but ehca does not support SRQ so we can leave wc->qp as
  NULL for ehca)
- Users that need the QP number can still get it through wc->qp->qp_num

Use case:

In IPoIB connected mode code, I have a common CQ shared by multiple
QPs.  To track connection usage, I need a way to get at some per-QP
context upon the completion, and I would like to avoid allocating
context object per work request just to stick a QP pointer into it.
With this code, I can just use wc->qp->qp_context.

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

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_cmd.c b/drivers/infiniband/hw/mthca/mthca_cmd.c
index 768df7265b8..968d1519761 100644
--- a/drivers/infiniband/hw/mthca/mthca_cmd.c
+++ b/drivers/infiniband/hw/mthca/mthca_cmd.c
@@ -1854,7 +1854,7 @@ int mthca_MAD_IFC(struct mthca_dev *dev, int ignore_mkey, int ignore_bkey,
 
                 memset(inbox + 256, 0, 256);
 
-                MTHCA_PUT(inbox, in_wc->qp_num,     MAD_IFC_MY_QPN_OFFSET);
+                MTHCA_PUT(inbox, in_wc->qp->qp_num, MAD_IFC_MY_QPN_OFFSET);
                 MTHCA_PUT(inbox, in_wc->src_qp,     MAD_IFC_RQPN_OFFSET);
 
                 val = in_wc->sl << 4;
diff --git a/drivers/infiniband/hw/mthca/mthca_cq.c b/drivers/infiniband/hw/mthca/mthca_cq.c
index 1159c8a0f2c..efd79ef109a 100644
--- a/drivers/infiniband/hw/mthca/mthca_cq.c
+++ b/drivers/infiniband/hw/mthca/mthca_cq.c
@@ -534,7 +534,7 @@ static inline int mthca_poll_one(struct mthca_dev *dev,
                 }
         }
 
-        entry->qp_num = (*cur_qp)->qpn;
+        entry->qp = &(*cur_qp)->ibqp;
 
         if (is_send) {
                 wq = &(*cur_qp)->sq;