From 0dbaee3b37e118a96bb7b8eb0d9bbaeeb46264be Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 13 Dec 2010 12:52:14 -0800 Subject: 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 --- net/ipv4/route.c | 24 +++++++++++++++++------- net/ipv4/tcp_ipv4.c | 2 +- net/ipv4/tcp_output.c | 14 +++++++++----- 3 files changed, 27 insertions(+), 13 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 770f70427f0..80997333db0 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -139,6 +139,7 @@ static unsigned long expires_ljiffies; */ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie); +static unsigned int ipv4_default_advmss(const struct dst_entry *dst); static void ipv4_dst_destroy(struct dst_entry *dst); static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst); static void ipv4_link_failure(struct sk_buff *skb); @@ -155,6 +156,7 @@ static struct dst_ops ipv4_dst_ops = { .protocol = cpu_to_be16(ETH_P_IP), .gc = rt_garbage_collect, .check = ipv4_dst_check, + .default_advmss = ipv4_default_advmss, .destroy = ipv4_dst_destroy, .ifdown = ipv4_dst_ifdown, .negative_advice = ipv4_negative_advice, @@ -383,8 +385,7 @@ static int rt_cache_seq_show(struct seq_file *seq, void *v) (__force u32)r->rt_gateway, r->rt_flags, atomic_read(&r->dst.__refcnt), r->dst.__use, 0, (__force u32)r->rt_src, - (dst_metric(&r->dst, RTAX_ADVMSS) ? - (int)dst_metric(&r->dst, RTAX_ADVMSS) + 40 : 0), + dst_metric_advmss(&r->dst) + 40, dst_metric(&r->dst, RTAX_WINDOW), (int)((dst_metric(&r->dst, RTAX_RTT) >> 3) + dst_metric(&r->dst, RTAX_RTTVAR)), @@ -1798,6 +1799,19 @@ static void set_class_tag(struct rtable *rt, u32 tag) } #endif +static unsigned int ipv4_default_advmss(const struct dst_entry *dst) +{ + unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS); + + if (advmss == 0) { + advmss = max_t(unsigned int, dst->dev->mtu - 40, + ip_rt_min_advmss); + if (advmss > 65535 - 40) + advmss = 65535 - 40; + } + return advmss; +} + static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag) { struct dst_entry *dst = &rt->dst; @@ -1823,11 +1837,7 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag) if (dst_mtu(dst) > IP_MAX_MTU) dst_metric_set(dst, RTAX_MTU, IP_MAX_MTU); - if (dst_metric(dst, RTAX_ADVMSS) == 0) - dst_metric_set(dst, RTAX_ADVMSS, - max_t(unsigned int, dst->dev->mtu - 40, - ip_rt_min_advmss)); - if (dst_metric(dst, RTAX_ADVMSS) > 65535 - 40) + if (dst_metric_raw(dst, RTAX_ADVMSS) > 65535 - 40) dst_metric_set(dst, RTAX_ADVMSS, 65535 - 40); #ifdef CONFIG_NET_CLS_ROUTE diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 4fc3387aa99..f4011027543 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1436,7 +1436,7 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, tcp_mtup_init(newsk); tcp_sync_mss(newsk, dst_mtu(dst)); - newtp->advmss = dst_metric(dst, RTAX_ADVMSS); + newtp->advmss = dst_metric_advmss(dst); if (tcp_sk(sk)->rx_opt.user_mss && tcp_sk(sk)->rx_opt.user_mss < newtp->advmss) newtp->advmss = tcp_sk(sk)->rx_opt.user_mss; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 97041f24cd2..2d390669d40 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; -- cgit v1.2.3-18-g5258