IB/mad: Add support for dual-sided RMPP transfers.

The implementation assumes that any RMPP request that requires a
response uses DS RMPP.  Based on the RMPP start-up scenarios defined
by the spec, this should be a valid assumption.  That is, there is no
start-up scenario defined where an RMPP request is followed by a
non-RMPP response.  By having this assumption we avoid any API
changes.

In order for a node that supports DS RMPP to communicate with one that
does not, RMPP responses assume a new window size of 1 if a DS ACK has
not been received.  (By DS ACK, I'm referring to the turn-around ACK
after the final ACK of the request.)  This is a slight spec deviation,
but is necessary to allow communication with nodes that do not
generate the DS ACK.  It also handles the case when a response is sent
after the request state has been discarded.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 87 insertions, 3 deletions

diff --git a/drivers/infiniband/core/mad_rmpp.c b/drivers/infiniband/core/mad_rmpp.c
index ebcd5b181770..74fe1af9b18a 100644
--- a/drivers/infiniband/core/mad_rmpp.c
+++ b/drivers/infiniband/core/mad_rmpp.c
@@ -60,6 +60,7 @@ struct mad_rmpp_recv {
         int last_ack;
         int seg_num;
         int newwin;
+        int repwin;
 
         __be64 tid;
         u32 src_qp;
@@ -170,6 +171,32 @@ static struct ib_mad_send_buf *alloc_response_msg(struct ib_mad_agent *agent,
         return msg;
 }
 
+static void ack_ds_ack(struct ib_mad_agent_private *agent,
+                       struct ib_mad_recv_wc *recv_wc)
+{
+        struct ib_mad_send_buf *msg;
+        struct ib_rmpp_mad *rmpp_mad;
+        int ret;
+
+        msg = alloc_response_msg(&agent->agent, recv_wc);
+        if (IS_ERR(msg))
+                return;
+
+        rmpp_mad = msg->mad;
+        memcpy(rmpp_mad, recv_wc->recv_buf.mad, msg->hdr_len);
+
+        rmpp_mad->mad_hdr.method ^= IB_MGMT_METHOD_RESP;
+        ib_set_rmpp_flags(&rmpp_mad->rmpp_hdr, IB_MGMT_RMPP_FLAG_ACTIVE);
+        rmpp_mad->rmpp_hdr.seg_num = 0;
+        rmpp_mad->rmpp_hdr.paylen_newwin = cpu_to_be32(1);
+
+        ret = ib_post_send_mad(msg, NULL);
+        if (ret) {
+                ib_destroy_ah(msg->ah);
+                ib_free_send_mad(msg);
+        }
+}
+
 void ib_rmpp_send_handler(struct ib_mad_send_wc *mad_send_wc)
 {
         struct ib_rmpp_mad *rmpp_mad = mad_send_wc->send_buf->mad;
@@ -271,6 +298,7 @@ create_rmpp_recv(struct ib_mad_agent_private *agent,
         rmpp_recv->newwin = 1;
         rmpp_recv->seg_num = 1;
         rmpp_recv->last_ack = 0;
+        rmpp_recv->repwin = 1;
 
         mad_hdr = &mad_recv_wc->recv_buf.mad->mad_hdr;
         rmpp_recv->tid = mad_hdr->tid;
@@ -591,6 +619,16 @@ static inline void adjust_last_ack(struct ib_mad_send_wr_private *wr,
                         break;
 }
 
+static void process_ds_ack(struct ib_mad_agent_private *agent,
+                           struct ib_mad_recv_wc *mad_recv_wc, int newwin)
+{
+        struct mad_rmpp_recv *rmpp_recv;
+
+        rmpp_recv = find_rmpp_recv(agent, mad_recv_wc);
+        if (rmpp_recv && rmpp_recv->state == RMPP_STATE_COMPLETE)
+                rmpp_recv->repwin = newwin;
+}
+
 static void process_rmpp_ack(struct ib_mad_agent_private *agent,
                              struct ib_mad_recv_wc *mad_recv_wc)
 {
@@ -616,8 +654,18 @@ static void process_rmpp_ack(struct ib_mad_agent_private *agent,
 
         spin_lock_irqsave(&agent->lock, flags);
         mad_send_wr = ib_find_send_mad(agent, mad_recv_wc);
-        if (!mad_send_wr)
-                goto out;       /* Unmatched ACK */
+        if (!mad_send_wr) {
+                if (!seg_num)
+                        process_ds_ack(agent, mad_recv_wc, newwin);
+                goto out;       /* Unmatched or DS RMPP ACK */
+        }
+
+        if ((mad_send_wr->last_ack == mad_send_wr->send_buf.seg_count) &&
+            (mad_send_wr->timeout)) {
+                spin_unlock_irqrestore(&agent->lock, flags);
+                ack_ds_ack(agent, mad_recv_wc);
+                return;         /* Repeated ACK for DS RMPP transaction */
+        }
 
         if ((mad_send_wr->last_ack == mad_send_wr->send_buf.seg_count) ||
             (!mad_send_wr->timeout) || (mad_send_wr->status != IB_WC_SUCCESS))
@@ -656,6 +704,9 @@ static void process_rmpp_ack(struct ib_mad_agent_private *agent,
                 if (mad_send_wr->refcount == 1)
                         ib_reset_mad_timeout(mad_send_wr,
                                              mad_send_wr->send_buf.timeout_ms);
+                spin_unlock_irqrestore(&agent->lock, flags);
+                ack_ds_ack(agent, mad_recv_wc);
+                return;
         } else if (mad_send_wr->refcount == 1 &&
                    mad_send_wr->seg_num < mad_send_wr->newwin &&
                    mad_send_wr->seg_num < mad_send_wr->send_buf.seg_count) {
@@ -772,6 +823,39 @@ out:
         return NULL;
 }
 
+static int init_newwin(struct ib_mad_send_wr_private *mad_send_wr)
+{
+        struct ib_mad_agent_private *agent = mad_send_wr->mad_agent_priv;
+        struct ib_mad_hdr *mad_hdr = mad_send_wr->send_buf.mad;
+        struct mad_rmpp_recv *rmpp_recv;
+        struct ib_ah_attr ah_attr;
+        unsigned long flags;
+        int newwin = 1;
+
+        if (!(mad_hdr->method & IB_MGMT_METHOD_RESP))
+                goto out;
+
+        spin_lock_irqsave(&agent->lock, flags);
+        list_for_each_entry(rmpp_recv, &agent->rmpp_list, list) {
+                if (rmpp_recv->tid != mad_hdr->tid ||
+                    rmpp_recv->mgmt_class != mad_hdr->mgmt_class ||
+                    rmpp_recv->class_version != mad_hdr->class_version ||
+                    (rmpp_recv->method & IB_MGMT_METHOD_RESP))
+                        continue;
+
+                if (ib_query_ah(mad_send_wr->send_buf.ah, &ah_attr))
+                        continue;
+
+                if (rmpp_recv->slid == ah_attr.dlid) {
+                        newwin = rmpp_recv->repwin;
+                        break;
+                }
+        }
+        spin_unlock_irqrestore(&agent->lock, flags);
+out:
+        return newwin;
+}
+
 int ib_send_rmpp_mad(struct ib_mad_send_wr_private *mad_send_wr)
 {
         struct ib_rmpp_mad *rmpp_mad;
@@ -787,7 +871,7 @@ int ib_send_rmpp_mad(struct ib_mad_send_wr_private *mad_send_wr)
                 return IB_RMPP_RESULT_INTERNAL;
         }
 
-        mad_send_wr->newwin = 1;
+        mad_send_wr->newwin = init_newwin(mad_send_wr);
 
         /* We need to wait for the final ACK even if there isn't a response */
         mad_send_wr->refcount += (mad_send_wr->timeout == 0);