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net: Abstract default ADVMSS behind an accessor.

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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
Download Patch File Download Diff File Expand all files Collapse all files

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;
}