infra: add gr_mbuf deepcopy

For packet duplication or fragmentation, traces must be duplicated
as the packet may go through different paths.

Add:
- a helper to copy traces
- a helper to copy the mbuf, its payload, specific mbuf_data and traces.

Signed-off-by: Christophe Fontaine <cfontain@redhat.com>

Author: christophefontaine

modules/infra/datapath/gr_mbuf.h

@@ -64,5 +64,22 @@ static inline bool gr_mbuf_is_traced(struct rte_mbuf *m) {
 // Returns a pointer to a gr_trace_item.data buffer.
 void *gr_mbuf_trace_add(struct rte_mbuf *m, struct rte_node *node, size_t data_len);
 
+// Copy all trace items from source mbuf to destination mbuf.
+//
+// This creates a deep copy of the entire trace chain, preserving timestamps,
+// node IDs, and trace data. Used when cloning packets to maintain trace history.
+void gr_mbuf_trace_copy(struct rte_mbuf *dst, struct rte_mbuf *src);
+
 // Detach the trace items from an mbuf and store them in the trace buffer.
 void gr_mbuf_trace_finish(struct rte_mbuf *m);
+
+// Deep copy of an mbuf: duplicates mbuf, copies mbuf priv data and traces
+static inline struct rte_mbuf *gr_mbuf_copy(struct rte_mbuf *m, size_t data_len, size_t priv_len) {
+	struct rte_mbuf *copy = rte_pktmbuf_copy(m, m->pool, 0, data_len);
+	if (copy) {
+		memcpy(mbuf_data(copy), mbuf_data(m), priv_len);
+		if (gr_mbuf_is_traced(m))
+			gr_mbuf_trace_copy(copy, m);
+	}
+	return copy;
+}

modules/infra/datapath/trace.c

@@ -618,6 +618,38 @@ void *gr_mbuf_trace_add(struct rte_mbuf *m, struct rte_node *node, size_t data_l
 	return trace->data;
 }
 
+void gr_mbuf_trace_copy(struct rte_mbuf *dst, struct rte_mbuf *src) {
+	struct gr_trace_head *src_traces = gr_mbuf_traces(src);
+	struct gr_trace_head *dst_traces = gr_mbuf_traces(dst);
+	struct gr_trace_item *src_trace, *dst_trace;
+	void *data;
+
+	// Reset trace head
+	STAILQ_INIT(dst_traces);
+
+	// Copy each trace item from source to destination
+	STAILQ_FOREACH (src_trace, src_traces, next) {
+		// Allocate new trace item for destination
+		while (rte_mempool_get(trace_pool, &data) < 0) {
+			void *oldest = NULL;
+			rte_ring_dequeue(traced_packets, &oldest);
+			free_trace(oldest);
+		}
+
+		dst_trace = data;
+
+		// Copy all trace item data
+		dst_trace->ts = src_trace->ts;
+		dst_trace->cpu_id = src_trace->cpu_id;
+		dst_trace->node_id = src_trace->node_id;
+		dst_trace->len = src_trace->len;
+		memcpy(dst_trace->data, src_trace->data, src_trace->len);
+
+		// Add to destination trace chain
+		STAILQ_INSERT_TAIL(dst_traces, dst_trace, next);
+	}
+}
+
 void gr_mbuf_trace_finish(struct rte_mbuf *m) {
 	struct gr_trace_head *traces = gr_mbuf_traces(m);
 	struct gr_trace_item *trace = STAILQ_FIRST(traces);

modules/ip/datapath/ip_fragment.c

@@ -96,7 +96,9 @@ ip_fragment_process(struct rte_graph *graph, struct rte_node *node, void **objs,
 		// Create and enqueue remaining fragments
 		for (i = 1; i < num_frags; i++) {
 			// Create new fragment, copying the original IPv4 header.
-			frag_mbuf = rte_pktmbuf_copy(mbuf, mbuf->pool, 0, ip_hdr_len);
+			frag_mbuf = gr_mbuf_copy(
+				mbuf, ip_hdr_len, sizeof(struct ip_output_mbuf_data)
+			);
 			if (unlikely(frag_mbuf == NULL)) {
 				break;
 			}
@@ -122,7 +124,6 @@ ip_fragment_process(struct rte_graph *graph, struct rte_node *node, void **objs,
 			frag_ip->hdr_checksum = 0;
 			frag_ip->hdr_checksum = rte_ipv4_cksum(frag_ip);
 
-			*ip_output_mbuf_data(frag_mbuf) = *ip_output_mbuf_data(mbuf);
 			frag_mbuf->packet_type = mbuf->packet_type;
 			if (gr_mbuf_is_traced(mbuf)) {
 				struct ip_fragment_trace_data *t;