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, 8 insertions, 5 deletions

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 5ed141ebd1c8..13efd4170349 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -642,7 +642,8 @@ static void snoop_recv(struct ib_mad_qp_info *qp_info,
 	spin_unlock_irqrestore(&qp_info->snoop_lock, flags);
 }
 
-static void build_smp_wc(u64 wr_id, u16 slid, u16 pkey_index, u8 port_num,
+static void build_smp_wc(struct ib_qp *qp,
+			 u64 wr_id, u16 slid, u16 pkey_index, u8 port_num,
 			 struct ib_wc *wc)
 {
 	memset(wc, 0, sizeof *wc);
@@ -652,7 +653,7 @@ static void build_smp_wc(u64 wr_id, u16 slid, u16 pkey_index, u8 port_num,
 	wc->pkey_index = pkey_index;
 	wc->byte_len = sizeof(struct ib_mad) + sizeof(struct ib_grh);
 	wc->src_qp = IB_QP0;
-	wc->qp_num = IB_QP0;
+	wc->qp = qp;
 	wc->slid = slid;
 	wc->sl = 0;
 	wc->dlid_path_bits = 0;
@@ -713,7 +714,8 @@ static int handle_outgoing_dr_smp(struct ib_mad_agent_private *mad_agent_priv,
 		goto out;
 	}
 
-	build_smp_wc(send_wr->wr_id, be16_to_cpu(smp->dr_slid),
+	build_smp_wc(mad_agent_priv->agent.qp,
+		     send_wr->wr_id, be16_to_cpu(smp->dr_slid),
 		     send_wr->wr.ud.pkey_index,
 		     send_wr->wr.ud.port_num, &mad_wc);
 
@@ -2355,7 +2357,8 @@ static void local_completions(struct work_struct *work)
 			 * Defined behavior is to complete response
 			 * before request
 			 */
-			build_smp_wc((unsigned long) local->mad_send_wr,
+			build_smp_wc(recv_mad_agent->agent.qp,
+				     (unsigned long) local->mad_send_wr,
 				     be16_to_cpu(IB_LID_PERMISSIVE),
 				     0, recv_mad_agent->agent.port_num, &wc);
 
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 743247ec065e..df1efbc10882 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -933,7 +933,7 @@ ssize_t ib_uverbs_poll_cq(struct ib_uverbs_file *file,
 		resp->wc[i].vendor_err 	   = wc[i].vendor_err;
 		resp->wc[i].byte_len 	   = wc[i].byte_len;
 		resp->wc[i].imm_data 	   = (__u32 __force) wc[i].imm_data;
-		resp->wc[i].qp_num 	   = wc[i].qp_num;
+		resp->wc[i].qp_num 	   = wc[i].qp->qp_num;
 		resp->wc[i].src_qp 	   = wc[i].src_qp;
 		resp->wc[i].wc_flags 	   = wc[i].wc_flags;
 		resp->wc[i].pkey_index 	   = wc[i].pkey_index;