netfilter: nf_nat: don't check if the tuple is unique when there isn't any other choice

The tuple got from unique_tuple() doesn't need to be really unique, so the
check for the unique tuple isn't necessary, when there isn't any other
choice. Eliminating the unnecessary nf_nat_used_tuple() can save some CPU
cycles too.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

3 files changed, 6 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/nf_nat_proto_common.c b/net/ipv4/netfilter/nf_nat_proto_common.c
index 2844a0383a11..3e61faf23a9a 100644
--- a/net/ipv4/netfilter/nf_nat_proto_common.c
+++ b/net/ipv4/netfilter/nf_nat_proto_common.c
@@ -81,9 +81,9 @@ void nf_nat_proto_unique_tuple(struct nf_conntrack_tuple *tuple,
         else
                 off = *rover;
 
-        for (i = 0; i < range_size; i++, off++) {
+        for (i = 0; ; ++off) {
                 *portptr = htons(min + off % range_size);
-                if (nf_nat_used_tuple(tuple, ct))
+                if (++i != range_size && nf_nat_used_tuple(tuple, ct))
                         continue;
                 if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
                         *rover = off;
diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c
index 89933ab6f63e..bc8d83a31c73 100644
--- a/net/ipv4/netfilter/nf_nat_proto_gre.c
+++ b/net/ipv4/netfilter/nf_nat_proto_gre.c
@@ -68,9 +68,9 @@ gre_unique_tuple(struct nf_conntrack_tuple *tuple,
 
         pr_debug("min = %u, range_size = %u\n", min, range_size);
 
-        for (i = 0; i < range_size; i++, key++) {
+        for (i = 0; ; ++key) {
                 *keyptr = htons(min + key % range_size);
-                if (!nf_nat_used_tuple(tuple, ct))
+                if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
                         return;
         }
 
diff --git a/net/ipv4/netfilter/nf_nat_proto_icmp.c b/net/ipv4/netfilter/nf_nat_proto_icmp.c
index 97003fe312e3..5744c3ec847c 100644
--- a/net/ipv4/netfilter/nf_nat_proto_icmp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_icmp.c
@@ -42,10 +42,10 @@ icmp_unique_tuple(struct nf_conntrack_tuple *tuple,
         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
                 range_size = 0xFFFF;
 
-        for (i = 0; i < range_size; i++, id++) {
+        for (i = 0; ; ++id) {
                 tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) +
                                              (id % range_size));
-                if (!nf_nat_used_tuple(tuple, ct))
+                if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
                         return;
         }
         return;