RDMA/iw_cxgb4: Low resource fixes for connection manager

Pre-allocate buffers for sending various control messages to close
connection, abort connection, etc so that we gracefully handle
connections when system is running out of memory.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -789,10 +789,29 @@ enum c4iw_ep_history {
 	CM_ID_DEREFED		= 28,
 };
 
+enum conn_pre_alloc_buffers {
+	CN_ABORT_REQ_BUF,
+	CN_ABORT_RPL_BUF,
+	CN_CLOSE_CON_REQ_BUF,
+	CN_DESTROY_BUF,
+	CN_FLOWC_BUF,
+	CN_MAX_CON_BUF
+};
+
+#define FLOWC_LEN 80
+union cpl_wr_size {
+	struct cpl_abort_req abrt_req;
+	struct cpl_abort_rpl abrt_rpl;
+	struct fw_ri_wr ri_req;
+	struct cpl_close_con_req close_req;
+	char flowc_buf[FLOWC_LEN];
+};
+
 struct c4iw_ep_common {
 	struct iw_cm_id *cm_id;
 	struct c4iw_qp *qp;
 	struct c4iw_dev *dev;
+	struct sk_buff_head ep_skb_list;
 	enum c4iw_ep_state state;
 	struct kref kref;
 	struct mutex mutex;

drivers/infiniband/hw/cxgb4/qp.c

@@ -1081,9 +1081,10 @@ static void post_terminate(struct c4iw_qp *qhp, struct t4_cqe *err_cqe,
 	PDBG("%s qhp %p qid 0x%x tid %u\n", __func__, qhp, qhp->wq.sq.qid,
 	     qhp->ep->hwtid);
 
-	skb = alloc_skb(sizeof *wqe, gfp);
-	if (!skb)
+	skb = skb_dequeue(&qhp->ep->com.ep_skb_list);
+	if (WARN_ON(!skb))
 		return;
+
 	set_wr_txq(skb, CPL_PRIORITY_DATA, qhp->ep->txq_idx);
 
 	wqe = (struct fw_ri_wr *)__skb_put(skb, sizeof(*wqe));
@@ -1202,9 +1203,10 @@ static int rdma_fini(struct c4iw_dev *rhp, struct c4iw_qp *qhp,
 	PDBG("%s qhp %p qid 0x%x tid %u\n", __func__, qhp, qhp->wq.sq.qid,
 	     ep->hwtid);
 
-	skb = alloc_skb(sizeof *wqe, GFP_KERNEL);
-	if (!skb)
+	skb = skb_dequeue(&ep->com.ep_skb_list);
+	if (WARN_ON(!skb))
 		return -ENOMEM;
+
 	set_wr_txq(skb, CPL_PRIORITY_DATA, ep->txq_idx);
 
 	wqe = (struct fw_ri_wr *)__skb_put(skb, sizeof(*wqe));