IB/mad: Fix ib_post_send_mad() returning 0 with no generate send comp

If ib_post_send_mad() returns 0, the API guarantees that there will be
a callback to send_buf->mad_agent->send_handler() so that the sender
can call ib_free_send_mad().  Otherwise, the ib_mad_send_buf will be
leaked and the mad_agent reference count will never go to zero and the
IB device module cannot be unloaded.  The above can happen without
this patch if process_mad() returns (IB_MAD_RESULT_SUCCESS |
IB_MAD_RESULT_CONSUMED).

If process_mad() returns IB_MAD_RESULT_SUCCESS and there is no agent
registered to receive the mad being sent, handle_outgoing_dr_smp()
returns zero which causes a MAD packet which is at the end of the
directed route to be incorrectly sent on the wire but doesn't cause a
hang since the HCA generates a send completion.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index dbcd285405ec1c9e30fe2571a7b4524d27e52e1f..de922a04ca2dbd5ca4f8696410750735bdaee681 100644 (file)
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -742,9 +742,7 @@ static int handle_outgoing_dr_smp(struct ib_mad_agent_private *mad_agent_priv,
                break;
        case IB_MAD_RESULT_SUCCESS | IB_MAD_RESULT_CONSUMED:
                kmem_cache_free(ib_mad_cache, mad_priv);
-               kfree(local);
-               ret = 1;
-               goto out;
+               break;
        case IB_MAD_RESULT_SUCCESS:
                /* Treat like an incoming receive MAD */
                port_priv = ib_get_mad_port(mad_agent_priv->agent.device,
@@ -755,10 +753,12 @@ static int handle_outgoing_dr_smp(struct ib_mad_agent_private *mad_agent_priv,
                                                        &mad_priv->mad.mad);
                }
                if (!port_priv || !recv_mad_agent) {
+                       /*
+                        * No receiving agent so drop packet and
+                        * generate send completion.
+                        */
                        kmem_cache_free(ib_mad_cache, mad_priv);
-                       kfree(local);
-                       ret = 0;
-                       goto out;
+                       break;
                }
                local->mad_priv = mad_priv;
                local->recv_mad_agent = recv_mad_agent;