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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>
This commit is contained in:
David S. Miller 2010-12-13 12:52:14 -08:00
parent cc6f02dd49
commit 0dbaee3b37
11 changed files with 75 additions and 33 deletions
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2
drivers/scsi/cxgbi/libcxgbi.c
View File

@ -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;

14
include/net/dst.h
View File

@ -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;

1
include/net/dst_ops.h
View File

@ -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);

4
net/decnet/af_decnet.c
View File

@ -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;

22
net/decnet/dn_route.c
View File

@ -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;
}

24
net/ipv4/route.c
View File

@ -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

2
net/ipv4/tcp_ipv4.c
View File

@ -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;

14
net/ipv4/tcp_output.c
View File

@ -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;

16
net/ipv6/route.c
View File

@ -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 @@ install_route:
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;
}

2
net/ipv6/tcp_ipv6.c
View File

@ -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;

7
net/xfrm/xfrm_policy.c
View File

@ -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))