ofproto-dpif: Maintain tun_id across action lists.

[sliver-openvswitch.git] / ofproto / ofproto-dpif.c

diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index bc54122..55b4e48 100644 (file)
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -6094,11 +6094,35 @@ action_xlate_ctx_init(struct action_xlate_ctx *ctx,
                       ovs_be16 initial_tci, struct rule_dpif *rule,
                       uint8_t tcp_flags, const struct ofpbuf *packet)
 {
+    ovs_be64 initial_tun_id = flow->tunnel.tun_id;
+
+    /* Flow initialization rules:
+     * - 'base_flow' must match the kernel's view of the packet at the
+     *   time that action processing starts.  'flow' represents any
+     *   transformations we wish to make through actions.
+     * - By default 'base_flow' and 'flow' are the same since the input
+     *   packet matches the output before any actions are applied.
+     * - When using VLAN splinters, 'base_flow''s VLAN is set to the value
+     *   of the received packet as seen by the kernel.  If we later output
+     *   to another device without any modifications this will cause us to
+     *   insert a new tag since the original one was stripped off by the
+     *   VLAN device.
+     * - Tunnel 'flow' is largely cleared when transitioning between
+     *   the input and output stages since it does not make sense to output
+     *   a packet with the exact headers that it was received with (i.e.
+     *   the destination IP is us).  The one exception is the tun_id, which
+     *   is preserved to allow use in later resubmit lookups and loads into
+     *   registers.
+     * - Tunnel 'base_flow' is completely cleared since that is what the
+     *   kernel does.  If we wish to maintain the original values an action
+     *   needs to be generated. */
+
     ctx->ofproto = ofproto;
     ctx->flow = *flow;
     memset(&ctx->flow.tunnel, 0, sizeof ctx->flow.tunnel);
     ctx->base_flow = ctx->flow;
     ctx->base_flow.vlan_tci = initial_tci;
+    ctx->flow.tunnel.tun_id = initial_tun_id;
     ctx->rule = rule;
     ctx->packet = packet;
     ctx->may_learn = packet != NULL;