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authorDavid S. Miller <davem@davemloft.net>2010-12-13 12:52:14 -0800
committerDavid S. Miller <davem@davemloft.net>2010-12-13 12:52:14 -0800
commit0dbaee3b37e118a96bb7b8eb0d9bbaeeb46264be (patch)
tree37000c5d7e663e4ae9800a7bcde9934984b8bae9 /net/ipv4/tcp_output.c
parentcc6f02dd490dac4ad821d5077b934c9b37037cd0 (diff)
net: Abstract default ADVMSS behind an accessor.
Make all RTAX_ADVMSS metric accesses go through a new helper function, dst_metric_advmss(). Leave the actual default metric as "zero" in the real metric slot, and compute the actual default value dynamically via a new dst_ops AF specific callback. For stacked IPSEC routes, we use the advmss of the path which preserves existing behavior. Unlike ipv4/ipv6, DecNET ties the advmss to the mtu and thus updates advmss on pmtu updates. This inconsistency in advmss handling results in more raw metric accesses than I wish we ended up with. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 97041f24cd27..2d390669d406 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -119,9 +119,13 @@ static __u16 tcp_advertise_mss(struct sock *sk)
struct dst_entry *dst = __sk_dst_get(sk);
int mss = tp->advmss;
- if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) {
- mss = dst_metric(dst, RTAX_ADVMSS);
- tp->advmss = mss;
+ if (dst) {
+ unsigned int metric = dst_metric_advmss(dst);
+
+ if (metric < mss) {
+ mss = metric;
+ tp->advmss = mss;
+ }
}
return (__u16)mss;
@@ -2422,7 +2426,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
skb_dst_set(skb, dst_clone(dst));
- mss = dst_metric(dst, RTAX_ADVMSS);
+ mss = dst_metric_advmss(dst);
if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss)
mss = tp->rx_opt.user_mss;
@@ -2556,7 +2560,7 @@ static void tcp_connect_init(struct sock *sk)
if (!tp->window_clamp)
tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
- tp->advmss = dst_metric(dst, RTAX_ADVMSS);
+ tp->advmss = dst_metric_advmss(dst);
if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss)
tp->advmss = tp->rx_opt.user_mss;