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https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-30 07:34:12 +08:00
ipv4: Cache learned PMTU information in inetpeer.
The general idea is that if we learn new PMTU information, we bump the peer genid. This triggers the dst_ops->check() code to validate and if necessary propagate the new PMTU value into the metrics. Learned PMTU information self-expires. This means that it is not necessary to kill a cached route entry just because the PMTU information is too old. As a consequence: 1) When the path appears unreachable (dst_ops->link_failure or dst_ops->negative_advice) we unwind the PMTU state if it is out of date, instead of killing the cached route. A redirected route will still be invalidated in these situations. 2) rt_check_expire(), rt_worker_func(), et al. are no longer necessary at all. Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
parent
d606ef3fe0
commit
2c8cec5c10
264
net/ipv4/route.c
264
net/ipv4/route.c
@ -131,9 +131,6 @@ static int ip_rt_min_pmtu __read_mostly = 512 + 20 + 20;
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static int ip_rt_min_advmss __read_mostly = 256;
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static int rt_chain_length_max __read_mostly = 20;
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static struct delayed_work expires_work;
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static unsigned long expires_ljiffies;
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/*
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* Interface to generic destination cache.
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*/
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@ -668,7 +665,7 @@ static inline int rt_fast_clean(struct rtable *rth)
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static inline int rt_valuable(struct rtable *rth)
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{
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return (rth->rt_flags & (RTCF_REDIRECTED | RTCF_NOTIFY)) ||
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rth->dst.expires;
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(rth->peer && rth->peer->pmtu_expires);
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}
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static int rt_may_expire(struct rtable *rth, unsigned long tmo1, unsigned long tmo2)
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@ -679,13 +676,7 @@ static int rt_may_expire(struct rtable *rth, unsigned long tmo1, unsigned long t
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if (atomic_read(&rth->dst.__refcnt))
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goto out;
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ret = 1;
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if (rth->dst.expires &&
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time_after_eq(jiffies, rth->dst.expires))
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goto out;
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age = jiffies - rth->dst.lastuse;
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ret = 0;
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if ((age <= tmo1 && !rt_fast_clean(rth)) ||
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(age <= tmo2 && rt_valuable(rth)))
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goto out;
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@ -829,97 +820,6 @@ static int has_noalias(const struct rtable *head, const struct rtable *rth)
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return ONE;
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}
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static void rt_check_expire(void)
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{
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static unsigned int rover;
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unsigned int i = rover, goal;
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struct rtable *rth;
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struct rtable __rcu **rthp;
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unsigned long samples = 0;
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unsigned long sum = 0, sum2 = 0;
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unsigned long delta;
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u64 mult;
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delta = jiffies - expires_ljiffies;
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expires_ljiffies = jiffies;
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mult = ((u64)delta) << rt_hash_log;
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if (ip_rt_gc_timeout > 1)
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do_div(mult, ip_rt_gc_timeout);
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goal = (unsigned int)mult;
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if (goal > rt_hash_mask)
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goal = rt_hash_mask + 1;
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for (; goal > 0; goal--) {
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unsigned long tmo = ip_rt_gc_timeout;
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unsigned long length;
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i = (i + 1) & rt_hash_mask;
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rthp = &rt_hash_table[i].chain;
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if (need_resched())
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cond_resched();
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samples++;
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if (rcu_dereference_raw(*rthp) == NULL)
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continue;
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length = 0;
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spin_lock_bh(rt_hash_lock_addr(i));
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while ((rth = rcu_dereference_protected(*rthp,
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lockdep_is_held(rt_hash_lock_addr(i)))) != NULL) {
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prefetch(rth->dst.rt_next);
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if (rt_is_expired(rth)) {
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*rthp = rth->dst.rt_next;
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rt_free(rth);
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continue;
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}
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if (rth->dst.expires) {
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/* Entry is expired even if it is in use */
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if (time_before_eq(jiffies, rth->dst.expires)) {
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nofree:
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tmo >>= 1;
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rthp = &rth->dst.rt_next;
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/*
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* We only count entries on
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* a chain with equal hash inputs once
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* so that entries for different QOS
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* levels, and other non-hash input
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* attributes don't unfairly skew
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* the length computation
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*/
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length += has_noalias(rt_hash_table[i].chain, rth);
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continue;
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}
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} else if (!rt_may_expire(rth, tmo, ip_rt_gc_timeout))
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goto nofree;
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/* Cleanup aged off entries. */
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*rthp = rth->dst.rt_next;
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rt_free(rth);
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}
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spin_unlock_bh(rt_hash_lock_addr(i));
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sum += length;
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sum2 += length*length;
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}
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if (samples) {
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unsigned long avg = sum / samples;
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unsigned long sd = int_sqrt(sum2 / samples - avg*avg);
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rt_chain_length_max = max_t(unsigned long,
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ip_rt_gc_elasticity,
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(avg + 4*sd) >> FRACT_BITS);
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}
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rover = i;
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}
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/*
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* rt_worker_func() is run in process context.
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* we call rt_check_expire() to scan part of the hash table
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*/
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static void rt_worker_func(struct work_struct *work)
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{
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rt_check_expire();
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schedule_delayed_work(&expires_work, ip_rt_gc_interval);
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}
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/*
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* Pertubation of rt_genid by a small quantity [1..256]
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* Using 8 bits of shuffling ensure we can call rt_cache_invalidate()
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@ -1535,9 +1435,7 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
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if (dst->obsolete > 0) {
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ip_rt_put(rt);
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ret = NULL;
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} else if ((rt->rt_flags & RTCF_REDIRECTED) ||
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(rt->dst.expires &&
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time_after_eq(jiffies, rt->dst.expires))) {
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} else if (rt->rt_flags & RTCF_REDIRECTED) {
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unsigned hash = rt_hash(rt->fl.fl4_dst, rt->fl.fl4_src,
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rt->fl.oif,
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rt_genid(dev_net(dst->dev)));
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@ -1547,6 +1445,14 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
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#endif
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rt_del(hash, rt);
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ret = NULL;
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} else if (rt->peer &&
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rt->peer->pmtu_expires &&
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time_after_eq(jiffies, rt->peer->pmtu_expires)) {
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unsigned long orig = rt->peer->pmtu_expires;
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if (cmpxchg(&rt->peer->pmtu_expires, orig, 0) == orig)
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dst_metric_set(dst, RTAX_MTU,
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rt->peer->pmtu_orig);
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}
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}
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return ret;
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@ -1697,80 +1603,78 @@ unsigned short ip_rt_frag_needed(struct net *net, struct iphdr *iph,
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unsigned short new_mtu,
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struct net_device *dev)
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{
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int i, k;
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unsigned short old_mtu = ntohs(iph->tot_len);
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struct rtable *rth;
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int ikeys[2] = { dev->ifindex, 0 };
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__be32 skeys[2] = { iph->saddr, 0, };
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__be32 daddr = iph->daddr;
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unsigned short est_mtu = 0;
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struct inet_peer *peer;
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for (k = 0; k < 2; k++) {
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for (i = 0; i < 2; i++) {
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unsigned hash = rt_hash(daddr, skeys[i], ikeys[k],
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rt_genid(net));
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peer = inet_getpeer_v4(iph->daddr, 1);
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if (peer) {
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unsigned short mtu = new_mtu;
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rcu_read_lock();
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for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
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rth = rcu_dereference(rth->dst.rt_next)) {
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unsigned short mtu = new_mtu;
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if (rth->fl.fl4_dst != daddr ||
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rth->fl.fl4_src != skeys[i] ||
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rth->rt_dst != daddr ||
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rth->rt_src != iph->saddr ||
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rth->fl.oif != ikeys[k] ||
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rt_is_input_route(rth) ||
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dst_metric_locked(&rth->dst, RTAX_MTU) ||
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!net_eq(dev_net(rth->dst.dev), net) ||
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rt_is_expired(rth))
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continue;
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if (new_mtu < 68 || new_mtu >= old_mtu) {
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/* BSD 4.2 compatibility hack :-( */
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if (mtu == 0 &&
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old_mtu >= dst_mtu(&rth->dst) &&
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old_mtu >= 68 + (iph->ihl << 2))
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old_mtu -= iph->ihl << 2;
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mtu = guess_mtu(old_mtu);
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}
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if (mtu <= dst_mtu(&rth->dst)) {
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if (mtu < dst_mtu(&rth->dst)) {
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dst_confirm(&rth->dst);
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if (mtu < ip_rt_min_pmtu) {
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u32 lock = dst_metric(&rth->dst,
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RTAX_LOCK);
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mtu = ip_rt_min_pmtu;
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lock |= (1 << RTAX_MTU);
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dst_metric_set(&rth->dst, RTAX_LOCK,
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lock);
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}
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dst_metric_set(&rth->dst, RTAX_MTU, mtu);
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dst_set_expires(&rth->dst,
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ip_rt_mtu_expires);
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}
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est_mtu = mtu;
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}
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}
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rcu_read_unlock();
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if (new_mtu < 68 || new_mtu >= old_mtu) {
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/* BSD 4.2 derived systems incorrectly adjust
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* tot_len by the IP header length, and report
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* a zero MTU in the ICMP message.
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*/
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if (mtu == 0 &&
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old_mtu >= 68 + (iph->ihl << 2))
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old_mtu -= iph->ihl << 2;
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mtu = guess_mtu(old_mtu);
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}
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if (mtu < ip_rt_min_pmtu)
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mtu = ip_rt_min_pmtu;
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if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {
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est_mtu = mtu;
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peer->pmtu_learned = mtu;
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peer->pmtu_expires = jiffies + ip_rt_mtu_expires;
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}
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inet_putpeer(peer);
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atomic_inc(&__rt_peer_genid);
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}
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return est_mtu ? : new_mtu;
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}
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static void check_peer_pmtu(struct dst_entry *dst, struct inet_peer *peer)
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{
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unsigned long expires = peer->pmtu_expires;
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if (time_before(expires, jiffies)) {
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u32 orig_dst_mtu = dst_mtu(dst);
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if (peer->pmtu_learned < orig_dst_mtu) {
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if (!peer->pmtu_orig)
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peer->pmtu_orig = dst_metric_raw(dst, RTAX_MTU);
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dst_metric_set(dst, RTAX_MTU, peer->pmtu_learned);
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}
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} else if (cmpxchg(&peer->pmtu_expires, expires, 0) == expires)
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dst_metric_set(dst, RTAX_MTU, peer->pmtu_orig);
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}
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static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
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{
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if (dst_mtu(dst) > mtu && mtu >= 68 &&
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!(dst_metric_locked(dst, RTAX_MTU))) {
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if (mtu < ip_rt_min_pmtu) {
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u32 lock = dst_metric(dst, RTAX_LOCK);
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struct rtable *rt = (struct rtable *) dst;
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struct inet_peer *peer;
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dst_confirm(dst);
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if (!rt->peer)
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rt_bind_peer(rt, 1);
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peer = rt->peer;
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if (peer) {
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if (mtu < ip_rt_min_pmtu)
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mtu = ip_rt_min_pmtu;
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dst_metric_set(dst, RTAX_LOCK, lock | (1 << RTAX_MTU));
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if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {
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peer->pmtu_learned = mtu;
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peer->pmtu_expires = jiffies + ip_rt_mtu_expires;
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atomic_inc(&__rt_peer_genid);
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rt->rt_peer_genid = rt_peer_genid();
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check_peer_pmtu(dst, peer);
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}
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dst_metric_set(dst, RTAX_MTU, mtu);
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dst_set_expires(dst, ip_rt_mtu_expires);
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inet_putpeer(peer);
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}
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}
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@ -1781,9 +1685,15 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
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if (rt_is_expired(rt))
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return NULL;
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if (rt->rt_peer_genid != rt_peer_genid()) {
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struct inet_peer *peer;
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if (!rt->peer)
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rt_bind_peer(rt, 0);
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peer = rt->peer;
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if (peer && peer->pmtu_expires)
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check_peer_pmtu(dst, peer);
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rt->rt_peer_genid = rt_peer_genid();
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}
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return dst;
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@ -1812,8 +1722,14 @@ static void ipv4_link_failure(struct sk_buff *skb)
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icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
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rt = skb_rtable(skb);
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if (rt)
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dst_set_expires(&rt->dst, 0);
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if (rt &&
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rt->peer &&
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rt->peer->pmtu_expires) {
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unsigned long orig = rt->peer->pmtu_expires;
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if (cmpxchg(&rt->peer->pmtu_expires, orig, 0) == orig)
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dst_metric_set(&rt->dst, RTAX_MTU, rt->peer->pmtu_orig);
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}
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}
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static int ip_rt_bug(struct sk_buff *skb)
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@ -1911,6 +1827,9 @@ static void rt_init_metrics(struct rtable *rt, struct fib_info *fi)
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memcpy(peer->metrics, fi->fib_metrics,
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sizeof(u32) * RTAX_MAX);
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dst_init_metrics(&rt->dst, peer->metrics, false);
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if (peer->pmtu_expires)
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check_peer_pmtu(&rt->dst, peer);
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} else {
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if (fi->fib_metrics != (u32 *) dst_default_metrics) {
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rt->fi = fi;
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@ -2961,7 +2880,8 @@ static int rt_fill_info(struct net *net,
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NLA_PUT_BE32(skb, RTA_MARK, rt->fl.mark);
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error = rt->dst.error;
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expires = rt->dst.expires ? rt->dst.expires - jiffies : 0;
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expires = (rt->peer && rt->peer->pmtu_expires) ?
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rt->peer->pmtu_expires - jiffies : 0;
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if (rt->peer) {
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inet_peer_refcheck(rt->peer);
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id = atomic_read(&rt->peer->ip_id_count) & 0xffff;
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@ -3418,14 +3338,6 @@ int __init ip_rt_init(void)
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devinet_init();
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ip_fib_init();
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/* All the timers, started at system startup tend
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to synchronize. Perturb it a bit.
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*/
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INIT_DELAYED_WORK_DEFERRABLE(&expires_work, rt_worker_func);
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expires_ljiffies = jiffies;
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schedule_delayed_work(&expires_work,
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net_random() % ip_rt_gc_interval + ip_rt_gc_interval);
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if (ip_rt_proc_init())
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printk(KERN_ERR "Unable to create route proc files\n");
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#ifdef CONFIG_XFRM
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