From 0dbaee3b37e118a96bb7b8eb0d9bbaeeb46264be Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 13 Dec 2010 12:52:14 -0800 Subject: [PATCH] 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 --- drivers/scsi/cxgbi/libcxgbi.c | 2 +- include/net/dst.h | 14 +++++++++++++- include/net/dst_ops.h | 1 + net/decnet/af_decnet.c | 4 ++-- net/decnet/dn_route.c | 22 ++++++++++++++++------ net/ipv4/route.c | 24 +++++++++++++++++------- net/ipv4/tcp_ipv4.c | 2 +- net/ipv4/tcp_output.c | 14 +++++++++----- net/ipv6/route.c | 16 +++++++--------- net/ipv6/tcp_ipv6.c | 2 +- net/xfrm/xfrm_policy.c | 7 +++++++ 11 files changed, 75 insertions(+), 33 deletions(-) diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c index be5661707dfa..d2ad3d676724 100644 --- a/drivers/scsi/cxgbi/libcxgbi.c +++ b/drivers/scsi/cxgbi/libcxgbi.c @@ -825,7 +825,7 @@ unsigned int cxgbi_sock_select_mss(struct cxgbi_sock *csk, unsigned int pmtu) unsigned int idx; struct dst_entry *dst = csk->dst; - csk->advmss = dst_metric(dst, RTAX_ADVMSS); + csk->advmss = dst_metric_advmss(dst); if (csk->advmss > pmtu - 40) csk->advmss = pmtu - 40; diff --git a/include/net/dst.h b/include/net/dst.h index 755ac6c1aa03..03a1c3d52d80 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -112,10 +112,22 @@ dst_metric_raw(const struct dst_entry *dst, const int metric) static inline u32 dst_metric(const struct dst_entry *dst, const int metric) { - WARN_ON_ONCE(metric == RTAX_HOPLIMIT); + WARN_ON_ONCE(metric == RTAX_HOPLIMIT || + metric == RTAX_ADVMSS); return dst_metric_raw(dst, metric); } +static inline u32 +dst_metric_advmss(const struct dst_entry *dst) +{ + u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); + + if (!advmss) + advmss = dst->ops->default_advmss(dst); + + return advmss; +} + static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) { dst->_metrics[metric-1] = val; diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h index 51665b3461b8..15fb7af08c42 100644 --- a/include/net/dst_ops.h +++ b/include/net/dst_ops.h @@ -16,6 +16,7 @@ struct dst_ops { int (*gc)(struct dst_ops *ops); struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); + unsigned int (*default_advmss)(const struct dst_entry *); void (*destroy)(struct dst_entry *); void (*ifdown)(struct dst_entry *, struct net_device *dev, int how); diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c index 0065e7e14af4..2af15b15d1fa 100644 --- a/net/decnet/af_decnet.c +++ b/net/decnet/af_decnet.c @@ -829,7 +829,7 @@ static int dn_confirm_accept(struct sock *sk, long *timeo, gfp_t allocation) return -EINVAL; scp->state = DN_CC; - scp->segsize_loc = dst_metric(__sk_dst_get(sk), RTAX_ADVMSS); + scp->segsize_loc = dst_metric_advmss(__sk_dst_get(sk)); dn_send_conn_conf(sk, allocation); prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); @@ -958,7 +958,7 @@ static int __dn_connect(struct sock *sk, struct sockaddr_dn *addr, int addrlen, sk->sk_route_caps = sk->sk_dst_cache->dev->features; sock->state = SS_CONNECTING; scp->state = DN_CI; - scp->segsize_loc = dst_metric(sk->sk_dst_cache, RTAX_ADVMSS); + scp->segsize_loc = dst_metric_advmss(sk->sk_dst_cache); dn_nsp_send_conninit(sk, NSP_CI); err = -EINPROGRESS; diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c index e2e926841fe6..b8a5c0515be8 100644 --- a/net/decnet/dn_route.c +++ b/net/decnet/dn_route.c @@ -110,6 +110,7 @@ static unsigned long dn_rt_deadline; static int dn_dst_gc(struct dst_ops *ops); static struct dst_entry *dn_dst_check(struct dst_entry *, __u32); +static unsigned int dn_dst_default_advmss(const struct dst_entry *dst); static struct dst_entry *dn_dst_negative_advice(struct dst_entry *); static void dn_dst_link_failure(struct sk_buff *); static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu); @@ -129,6 +130,7 @@ static struct dst_ops dn_dst_ops = { .gc_thresh = 128, .gc = dn_dst_gc, .check = dn_dst_check, + .default_advmss = dn_dst_default_advmss, .negative_advice = dn_dst_negative_advice, .link_failure = dn_dst_link_failure, .update_pmtu = dn_dst_update_pmtu, @@ -245,7 +247,8 @@ static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu) } if (!(dst_metric_locked(dst, RTAX_ADVMSS))) { u32 mss = mtu - DN_MAX_NSP_DATA_HEADER; - if (dst_metric(dst, RTAX_ADVMSS) > mss) + u32 existing_mss = dst_metric_raw(dst, RTAX_ADVMSS); + if (!existing_mss || existing_mss > mss) dst_metric_set(dst, RTAX_ADVMSS, mss); } } @@ -795,12 +798,17 @@ static int dn_rt_bug(struct sk_buff *skb) return NET_RX_DROP; } +static unsigned int dn_dst_default_advmss(const struct dst_entry *dst) +{ + return dn_mss_from_pmtu(dst->dev, dst_mtu(dst)); +} + static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res) { struct dn_fib_info *fi = res->fi; struct net_device *dev = rt->dst.dev; struct neighbour *n; - unsigned mss; + unsigned int metric; if (fi) { if (DN_FIB_RES_GW(*res) && @@ -820,10 +828,12 @@ static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res) if (dst_metric(&rt->dst, RTAX_MTU) == 0 || dst_metric(&rt->dst, RTAX_MTU) > rt->dst.dev->mtu) dst_metric_set(&rt->dst, RTAX_MTU, rt->dst.dev->mtu); - mss = dn_mss_from_pmtu(dev, dst_mtu(&rt->dst)); - if (dst_metric(&rt->dst, RTAX_ADVMSS) == 0 || - dst_metric(&rt->dst, RTAX_ADVMSS) > mss) - dst_metric_set(&rt->dst, RTAX_ADVMSS, mss); + metric = dst_metric_raw(&rt->dst, RTAX_ADVMSS); + if (metric) { + unsigned int mss = dn_mss_from_pmtu(dev, dst_mtu(&rt->dst)); + if (metric > mss) + dst_metric_set(&rt->dst, RTAX_ADVMSS, mss); + } return 0; } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 770f70427f0b..80997333db0c 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 4fc3387aa994..f4011027543d 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 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; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 98796b0dc2b7..d9cb832be529 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -76,6 +76,7 @@ static struct rt6_info * ip6_rt_copy(struct rt6_info *ort); static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie); +static unsigned int ip6_default_advmss(const struct dst_entry *dst); static struct dst_entry *ip6_negative_advice(struct dst_entry *); static void ip6_dst_destroy(struct dst_entry *); static void ip6_dst_ifdown(struct dst_entry *, @@ -103,6 +104,7 @@ static struct dst_ops ip6_dst_ops_template = { .gc = ip6_dst_gc, .gc_thresh = 1024, .check = ip6_dst_check, + .default_advmss = ip6_default_advmss, .destroy = ip6_dst_destroy, .ifdown = ip6_dst_ifdown, .negative_advice = ip6_negative_advice, @@ -937,8 +939,12 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, u32 mtu) static int ipv6_get_mtu(struct net_device *dev); -static inline unsigned int ipv6_advmss(struct net *net, unsigned int mtu) +static unsigned int ip6_default_advmss(const struct dst_entry *dst) { + struct net_device *dev = dst->dev; + unsigned int mtu = dst_mtu(dst); + struct net *net = dev_net(dev); + mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr); if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss) @@ -990,7 +996,6 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev, atomic_set(&rt->dst.__refcnt, 1); dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 255); dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev)); - dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst))); rt->dst.output = ip6_output; #if 0 /* there's no chance to use these for ndisc */ @@ -1312,8 +1317,6 @@ int ip6_route_add(struct fib6_config *cfg) if (!dst_mtu(&rt->dst)) dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(dev)); - if (!dst_metric(&rt->dst, RTAX_ADVMSS)) - dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst))); rt->dst.dev = dev; rt->rt6i_idev = idev; rt->rt6i_table = table; @@ -1540,8 +1543,6 @@ void rt6_redirect(struct in6_addr *dest, struct in6_addr *src, nrt->rt6i_nexthop = neigh_clone(neigh); /* Reset pmtu, it may be better */ dst_metric_set(&nrt->dst, RTAX_MTU, ipv6_get_mtu(neigh->dev)); - dst_metric_set(&nrt->dst, RTAX_ADVMSS, ipv6_advmss(dev_net(neigh->dev), - dst_mtu(&nrt->dst))); if (ip6_ins_rt(nrt)) goto out; @@ -1971,7 +1972,6 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev, rt->rt6i_dev = net->loopback_dev; rt->rt6i_idev = idev; dst_metric_set(&rt->dst, RTAX_MTU, ipv6_get_mtu(rt->rt6i_dev)); - dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, dst_mtu(&rt->dst))); dst_metric_set(&rt->dst, RTAX_HOPLIMIT, -1); rt->dst.obsolete = -1; @@ -2041,7 +2041,6 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg) { struct rt6_mtu_change_arg *arg = (struct rt6_mtu_change_arg *) p_arg; struct inet6_dev *idev; - struct net *net = dev_net(arg->dev); /* In IPv6 pmtu discovery is not optional, so that RTAX_MTU lock cannot disable it. @@ -2073,7 +2072,6 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg) (dst_mtu(&rt->dst) < arg->mtu && dst_mtu(&rt->dst) == idev->cnf.mtu6))) { dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu); - dst_metric_set(&rt->dst, RTAX_ADVMSS, ipv6_advmss(net, arg->mtu)); } return 0; } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index fee076891646..20aa95e37359 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1521,7 +1521,7 @@ static struct sock * tcp_v6_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); tcp_initialize_rcv_mss(newsk); newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6; diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 6e50ccd8c532..36936c8ae961 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -2361,6 +2361,11 @@ static int xfrm_bundle_ok(struct xfrm_policy *pol, struct xfrm_dst *first, return 1; } +static unsigned int xfrm_default_advmss(const struct dst_entry *dst) +{ + return dst_metric_advmss(dst->path); +} + int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo) { struct net *net; @@ -2378,6 +2383,8 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo) dst_ops->kmem_cachep = xfrm_dst_cache; if (likely(dst_ops->check == NULL)) dst_ops->check = xfrm_dst_check; + if (likely(dst_ops->default_advmss == NULL)) + dst_ops->default_advmss = xfrm_default_advmss; if (likely(dst_ops->negative_advice == NULL)) dst_ops->negative_advice = xfrm_negative_advice; if (likely(dst_ops->link_failure == NULL))