Add a function named packet_new_nocopy for COLO.

Use the packet_new_nocopy instead of packet_new in the
filter-rewriter module. There will be one less memory
copy in the processing of each network packet.

Signed-off-by: Lei Rao <lei.rao@intel.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/colo.c

@@ -157,19 +157,28 @@ void connection_destroy(void *opaque)
 
 Packet *packet_new(const void *data, int size, int vnet_hdr_len)
 {
-    Packet *pkt = g_slice_new(Packet);
+    Packet *pkt = g_slice_new0(Packet);
 
     pkt->data = g_memdup(data, size);
     pkt->size = size;
     pkt->creation_ms = qemu_clock_get_ms(QEMU_CLOCK_HOST);
     pkt->vnet_hdr_len = vnet_hdr_len;
-    pkt->tcp_seq = 0;
+
-    pkt->tcp_ack = 0;
+    return pkt;
-    pkt->seq_end = 0;
+}
-    pkt->header_size = 0;
+
-    pkt->payload_size = 0;
+/*
-    pkt->offset = 0;
+ * packet_new_nocopy will not copy data, so the caller can't release
-    pkt->flags = 0;
+ * the data. And it will be released in packet_destroy.
+ */
+Packet *packet_new_nocopy(void *data, int size, int vnet_hdr_len)
+{
+    Packet *pkt = g_slice_new0(Packet);
+
+    pkt->data = data;
+    pkt->size = size;
+    pkt->creation_ms = qemu_clock_get_ms(QEMU_CLOCK_HOST);
+    pkt->vnet_hdr_len = vnet_hdr_len;
 
     return pkt;
 }

net/colo.h

@@ -101,6 +101,7 @@ bool connection_has_tracked(GHashTable *connection_track_table,
                             ConnectionKey *key);
 void connection_hashtable_reset(GHashTable *connection_track_table);
 Packet *packet_new(const void *data, int size, int vnet_hdr_len);
+Packet *packet_new_nocopy(void *data, int size, int vnet_hdr_len);
 void packet_destroy(void *opaque, void *user_data);
 void packet_destroy_partial(void *opaque, void *user_data);
 

net/filter-rewriter.c

@@ -270,8 +270,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
         vnet_hdr_len = nf->netdev->vnet_hdr_len;
     }
 
-    pkt = packet_new(buf, size, vnet_hdr_len);
+    pkt = packet_new_nocopy(buf, size, vnet_hdr_len);
-    g_free(buf);
 
     /*
      * if we get tcp packet