classifier: Make classifier_lookup() 'flow' parameter non-const.

An upcoming commit will make classifier_lookup() sometimes modify its
'flow' argument temporarily during the lookup.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
---
v2: New patch.
v2.1: Rebase.
v3: Rebase.

lib/classifier.c

@@ -816,9 +816,12 @@ trie_ctx_init(struct trie_ctx *ctx, const struct cls_trie *trie)
  * If a rule is found and 'wc' is non-null, bitwise-OR's 'wc' with the
  * set of bits that were significant in the lookup.  At some point
  * earlier, 'wc' should have been initialized (e.g., by
- * flow_wildcards_init_catchall()). */
+ * flow_wildcards_init_catchall()).
+ *
+ * 'flow' is non-const to allow for temporary modifications during the lookup.
+ * Any changes are restored before returning. */
 const struct cls_rule *
-classifier_lookup(const struct classifier *cls, const struct flow *flow,
+classifier_lookup(const struct classifier *cls, struct flow *flow,
                   struct flow_wildcards *wc)
 {
     const struct cls_partition *partition;

lib/classifier.h

@@ -295,7 +295,7 @@ static inline void classifier_publish(struct classifier *);
 /* Lookups.  These are RCU protected and may run concurrently with modifiers
  * and each other. */
 const struct cls_rule *classifier_lookup(const struct classifier *,
-                                         const struct flow *,
+                                         struct flow *,
                                          struct flow_wildcards *);
 bool classifier_rule_overlaps(const struct classifier *,
                               const struct cls_rule *);

lib/tnl-ports.c

@@ -134,8 +134,10 @@ tnl_port_map_delete(ovs_be32 ip_dst, ovs_be16 udp_port)
     tnl_port_unref(cr);
 }
 
+/* 'flow' is non-const to allow for temporary modifications during the lookup.
+ * Any changes are restored before returning. */
 odp_port_t
-tnl_port_map_lookup(const struct flow *flow, struct flow_wildcards *wc)
+tnl_port_map_lookup(struct flow *flow, struct flow_wildcards *wc)
 {
     const struct cls_rule *cr = classifier_lookup(&cls, flow, wc);
 

lib/tnl-ports.h

@@ -24,8 +24,7 @@
 #include "packets.h"
 #include "util.h"
 
-odp_port_t tnl_port_map_lookup(const struct flow *flow,
-                           struct flow_wildcards *wc);
+odp_port_t tnl_port_map_lookup(struct flow *flow, struct flow_wildcards *wc);
 
 void tnl_port_map_insert(odp_port_t port, ovs_be32 ip_dst, ovs_be16 udp_port,
                          const char dev_name[]);

ofproto/ofproto-dpif.c

@@ -3735,10 +3735,13 @@ rule_dpif_lookup(struct ofproto_dpif *ofproto, struct flow *flow,
 
 /* The returned rule (if any) is valid at least until the next RCU quiescent
  * period.  If the rule needs to stay around longer, a non-zero 'take_ref'
- * must be passed in to cause a reference to be taken on it. */
+ * must be passed in to cause a reference to be taken on it.
+ *
+ * 'flow' is non-const to allow for temporary modifications during the lookup.
+ * Any changes are restored before returning. */
 static struct rule_dpif *
 rule_dpif_lookup_in_table(struct ofproto_dpif *ofproto, uint8_t table_id,
-                          const struct flow *flow, struct flow_wildcards *wc,
+                          struct flow *flow, struct flow_wildcards *wc,
                           bool take_ref)
 {
     struct classifier *cls = &ofproto->up.tables[table_id].cls;
@@ -3778,7 +3781,10 @@ rule_dpif_lookup_in_table(struct ofproto_dpif *ofproto, uint8_t table_id,
  * on it before this returns.
  *
  * 'in_port' allows the lookup to take place as if the in port had the value
- * 'in_port'.  This is needed for resubmit action support. */
+ * 'in_port'.  This is needed for resubmit action support.
+ *
+ * 'flow' is non-const to allow for temporary modifications during the lookup.
+ * Any changes are restored before returning. */
 struct rule_dpif *
 rule_dpif_lookup_from_table(struct ofproto_dpif *ofproto, struct flow *flow,
                             struct flow_wildcards *wc, bool take_ref,