IB/mad: Convert allocations from kmem_cache to kzalloc

This patch implements allocating alternate receive MAD buffers within the MAD
stack.  Support for OPA to send/recv variable sized MADs is implemented later.

    1) Convert MAD allocations from kmem_cache to kzalloc

       kzalloc is more flexible to support devices with different sized MADs
       and research and testing showed that the current use of kmem_cache does
       not provide performance benefits over kzalloc.

    2) Change struct ib_mad_private to use a flex array for the mad data
    3) Allocate ib_mad_private based on the size specified by devices in
       rdma_max_mad_size.
    4) Carry the allocated size in ib_mad_private to be used when processing
       ib_mad_private objects.
    5) Alter DMA mappings based on the mad_size of ib_mad_private.
    6) Replace the use of sizeof and static defines as appropriate
    7) Add appropriate casts for the MAD data when calling processing
       functions.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/agent.c

@@ -78,9 +78,9 @@ ib_get_agent_port(const struct ib_device *device, int port_num)
 	return entry;
 }
 
-void agent_send_response(const struct ib_mad *mad, const struct ib_grh *grh,
+void agent_send_response(const struct ib_mad_hdr *mad_hdr, const struct ib_grh *grh,
 			 const struct ib_wc *wc, const struct ib_device *device,
-			 int port_num, int qpn)
+			 int port_num, int qpn, size_t resp_mad_len)
 {
 	struct ib_agent_port_private *port_priv;
 	struct ib_mad_agent *agent;
@@ -107,7 +107,8 @@ void agent_send_response(const struct ib_mad *mad, const struct ib_grh *grh,
 	}
 
 	send_buf = ib_create_send_mad(agent, wc->src_qp, wc->pkey_index, 0,
-				      IB_MGMT_MAD_HDR, IB_MGMT_MAD_DATA,
+				      IB_MGMT_MAD_HDR,
+				      resp_mad_len - IB_MGMT_MAD_HDR,
 				      GFP_KERNEL,
 				      IB_MGMT_BASE_VERSION);
 	if (IS_ERR(send_buf)) {
@@ -115,7 +116,7 @@ void agent_send_response(const struct ib_mad *mad, const struct ib_grh *grh,
 		goto err1;
 	}
 
-	memcpy(send_buf->mad, mad, sizeof *mad);
+	memcpy(send_buf->mad, mad_hdr, resp_mad_len);
 	send_buf->ah = ah;
 
 	if (device->node_type == RDMA_NODE_IB_SWITCH) {

drivers/infiniband/core/agent.h

@@ -44,8 +44,8 @@ extern int ib_agent_port_open(struct ib_device *device, int port_num);
 
 extern int ib_agent_port_close(struct ib_device *device, int port_num);
 
-extern void agent_send_response(const struct ib_mad *mad, const struct ib_grh *grh,
+extern void agent_send_response(const struct ib_mad_hdr *mad_hdr, const struct ib_grh *grh,
 				const struct ib_wc *wc, const struct ib_device *device,
-				int port_num, int qpn);
+				int port_num, int qpn, size_t resp_mad_len);
 
 #endif	/* __AGENT_H_ */

drivers/infiniband/core/mad_priv.h

@@ -75,12 +75,9 @@ struct ib_mad_private_header {
 
 struct ib_mad_private {
 	struct ib_mad_private_header header;
+	size_t mad_size;
 	struct ib_grh grh;
-	union {
-		struct ib_mad mad;
-		struct ib_rmpp_mad rmpp_mad;
-		struct ib_smp smp;
-	} mad;
+	u8 mad[0];
 } __attribute__ ((packed));
 
 struct ib_rmpp_segment {