ipv4: defer fib_compute_spec_dst() call
ip_options_compile() can avoid calling fib_compute_spec_dst()
by default, and perform the call only if needed.
David suggested to add a helper to make the call only once.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 1f02251..a19d647 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -242,6 +242,15 @@
opt->ts_needtime = 0;
}
+/* helper used by ip_options_compile() to call fib_compute_spec_dst()
+ * at most one time.
+ */
+static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
+{
+ if (*spec_dst == htonl(INADDR_ANY))
+ *spec_dst = fib_compute_spec_dst(skb);
+}
+
/*
* Verify options and fill pointers in struct options.
* Caller should clear *opt, and set opt->data.
@@ -251,7 +260,7 @@
int ip_options_compile(struct net *net,
struct ip_options *opt, struct sk_buff *skb)
{
- __be32 spec_dst = (__force __be32) 0;
+ __be32 spec_dst = htonl(INADDR_ANY);
unsigned char *pp_ptr = NULL;
struct rtable *rt = NULL;
unsigned char *optptr;
@@ -260,8 +269,6 @@
if (skb != NULL) {
rt = skb_rtable(skb);
- if (rt)
- spec_dst = fib_compute_spec_dst(skb);
optptr = (unsigned char *)&(ip_hdr(skb)[1]);
} else
optptr = opt->__data;
@@ -334,6 +341,7 @@
goto error;
}
if (rt) {
+ spec_dst_fill(&spec_dst, skb);
memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
opt->is_changed = 1;
}
@@ -376,6 +384,7 @@
}
opt->ts = optptr - iph;
if (rt) {
+ spec_dst_fill(&spec_dst, skb);
memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
timeptr = &optptr[optptr[2]+3];
}