Removed redundant code.
---
The purpose of this patch is to cause the ib_mad driver to discard busy 
responses from the SA, effectively causing busy responses to become time outs.

This ensures that naïve IB applications cannot overwhelm the SA with queries, 
which could happen when a cluster is being rebooted, or when a large HPC 
application is started.

Signed-Off-By: Michael Heinz <[email protected]>

----
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 64e660c..10fead0 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -1828,14 +1828,21 @@ static void ib_mad_complete_recv(struct 
ib_mad_agent_private *mad_agent_priv,
 
        /* Complete corresponding request */
        if (ib_response_mad(mad_recv_wc->recv_buf.mad)) {
+               u16 busy = 
be16_to_cpu(mad_recv_wc->recv_buf.mad->mad_hdr.status) &
+                                                          
IB_MGMT_MAD_STATUS_BUSY;
+
                spin_lock_irqsave(&mad_agent_priv->lock, flags);
                mad_send_wr = ib_find_send_mad(mad_agent_priv, mad_recv_wc);
-               if (!mad_send_wr) {
+               if (!mad_send_wr ||
+                       (busy && mad_send_wr->retries_left &&
+                        (mad_recv_wc->recv_buf.mad->mad_hdr.method != 
+                         IB_MGMT_METHOD_TRAP_REPRESS))) {
                        spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
                        ib_free_recv_mad(mad_recv_wc);
                        deref_mad_agent(mad_agent_priv);
                        return;
                }
+
                ib_mark_mad_done(mad_send_wr);
                spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
 
diff --git a/include/rdma/ib_mad.h b/include/rdma/ib_mad.h
index d3b9401..b901968 100644
--- a/include/rdma/ib_mad.h
+++ b/include/rdma/ib_mad.h
@@ -77,6 +77,15 @@
 
 #define IB_MGMT_MAX_METHODS                    128
 
+/* MAD Status field bit masks */
+#define IB_MGMT_MAD_STATUS_SUCCESS                      0x0000
+#define IB_MGMT_MAD_STATUS_BUSY                         0x0001
+#define IB_MGMT_MAD_STATUS_REDIRECT_REQD                0x0002
+#define IB_MGMT_MAD_STATUS_BAD_VERSION                  0x0004
+#define IB_MGMT_MAD_STATUS_UNSUPPORTED_METHOD           0x0008
+#define IB_MGMT_MAD_STATUS_UNSUPPORTED_METHOD_ATTRIB    0x000c
+#define IB_MGMT_MAD_STATUS_INVALID_ATTRIB_VALUE         0x001c
+
 /* RMPP information */
 #define IB_MGMT_RMPP_VERSION                   1
 


Attachment: sa_busy_20101206.patch
Description: sa_busy_20101206.patch

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