mbuf: add a function to linearize a packet

[dpdk.git] / lib / librte_mbuf / rte_mbuf.h

diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index ffbb4b3..bfce9f4 100644 (file)
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1716,6 +1716,57 @@ rte_validate_tx_offload(const struct rte_mbuf *m)
        return 0;
 }
 
+/**
+ * Linearize data in mbuf.
+ *
+ * This function moves the mbuf data in the first segment if there is enough
+ * tailroom. The subsequent segments are unchained and freed.
+ *
+ * @param mbuf
+ *   mbuf to linearize
+ * @return
+ *   - 0, on success
+ *   - -1, on error
+ */
+static inline int
+rte_pktmbuf_linearize(struct rte_mbuf *mbuf)
+{
+       int seg_len, copy_len;
+       struct rte_mbuf *m;
+       struct rte_mbuf *m_next;
+       char *buffer;
+
+       if (rte_pktmbuf_is_contiguous(mbuf))
+               return 0;
+
+       /* Extend first segment to the total packet length */
+       copy_len = rte_pktmbuf_pkt_len(mbuf) - rte_pktmbuf_data_len(mbuf);
+
+       if (unlikely(copy_len > rte_pktmbuf_tailroom(mbuf)))
+               return -1;
+
+       buffer = rte_pktmbuf_mtod_offset(mbuf, char *, mbuf->data_len);
+       mbuf->data_len = (uint16_t)(mbuf->pkt_len);
+
+       /* Append data from next segments to the first one */
+       m = mbuf->next;
+       while (m != NULL) {
+               m_next = m->next;
+
+               seg_len = rte_pktmbuf_data_len(m);
+               rte_memcpy(buffer, rte_pktmbuf_mtod(m, char *), seg_len);
+               buffer += seg_len;
+
+               rte_pktmbuf_free_seg(m);
+               m = m_next;
+       }
+
+       mbuf->next = NULL;
+       mbuf->nb_segs = 1;
+
+       return 0;
+}
+
 /**
  * Dump an mbuf structure to a file.
  *