@@ -27,6 +27,12 @@ min_adv_mss - INTEGER
The advertised MSS depends on the first hop route MTU, but will
never be lower than this setting.
+rt_cache_rebuild_count - INTEGER
+ The per net-namespace route cache emergency rebuild threshold.
+ Any net-namespace having its route cache rebuilt due to
+ a hash bucket chain being too long more than this many times
+ will have its route caching disabled
+
IP Fragmentation:
ipfrag_high_thresh - INTEGER
@@ -49,6 +49,8 @@ struct netns_ipv4 {
int sysctl_icmp_ratelimit;
int sysctl_icmp_ratemask;
int sysctl_icmp_errors_use_inbound_ifaddr;
+ int sysctl_rt_cache_rebuild_count;
+ int current_rt_cache_rebuild_count;
struct timer_list rt_secret_timer;
atomic_t rt_genid;
@@ -129,6 +129,7 @@ static int ip_rt_mtu_expires __read_mostly = 10 * 60 * HZ;
static int ip_rt_min_pmtu __read_mostly = 512 + 20 + 20;
static int ip_rt_min_advmss __read_mostly = 256;
static int ip_rt_secret_interval __read_mostly = 10 * 60 * HZ;
+static int rt_chain_length_max __read_mostly = 20;
static void rt_worker_func(struct work_struct *work);
static DECLARE_DELAYED_WORK(expires_work, rt_worker_func);
@@ -145,6 +146,7 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
static void ipv4_link_failure(struct sk_buff *skb);
static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu);
static int rt_garbage_collect(struct dst_ops *ops);
+static void rt_emergency_hash_rebuild(struct net *net);
static struct dst_ops ipv4_dst_ops = {
@@ -201,6 +203,7 @@ const __u8 ip_tos2prio[16] = {
struct rt_hash_bucket {
struct rtable *chain;
};
+
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
defined(CONFIG_PROVE_LOCKING)
/*
@@ -674,6 +677,20 @@ static inline u32 rt_score(struct rtable *rt)
return score;
}
+static inline bool rt_caching(const struct net *net)
+{
+ return net->ipv4.current_rt_cache_rebuild_count <=
+ net->ipv4.sysctl_rt_cache_rebuild_count;
+}
+
+static inline bool compare_hash_inputs(const struct flowi *fl1,
+ const struct flowi *fl2)
+{
+ return (__force u32)(((fl1->nl_u.ip4_u.daddr ^ fl2->nl_u.ip4_u.daddr) |
+ (fl1->nl_u.ip4_u.saddr ^ fl2->nl_u.ip4_u.saddr) |
+ (fl1->iif ^ fl2->iif)) == 0);
+}
+
static inline int compare_keys(struct flowi *fl1, struct flowi *fl2)
{
return ((__force u32)((fl1->nl_u.ip4_u.daddr ^ fl2->nl_u.ip4_u.daddr) |
@@ -753,11 +770,24 @@ static void rt_do_flush(int process_context)
}
}
+/*
+ * While freeing expired entries, we compute average chain length
+ * and standard deviation, using fixed-point arithmetic.
+ * This to have an estimation of rt_chain_length_max
+ * rt_chain_length_max = max(elasticity, AVG + 4*SD)
+ * We use 3 bits for frational part, and 29 (or 61) for magnitude.
+ */
+
+#define FRACT_BITS 3
+#define ONE (1UL << FRACT_BITS)
+
static void rt_check_expire(void)
{
static unsigned int rover;
unsigned int i = rover, goal;
struct rtable *rth, **rthp;
+ unsigned long length = 0, samples = 0;
+ unsigned long sum = 0, sum2 = 0;
u64 mult;
mult = ((u64)ip_rt_gc_interval) << rt_hash_log;
@@ -766,6 +796,7 @@ static void rt_check_expire(void)
goal = (unsigned int)mult;
if (goal > rt_hash_mask)
goal = rt_hash_mask + 1;
+ length = 0;
for (; goal > 0; goal--) {
unsigned long tmo = ip_rt_gc_timeout;
@@ -775,6 +806,8 @@ static void rt_check_expire(void)
if (need_resched())
cond_resched();
+ samples++;
+
if (*rthp == NULL)
continue;
spin_lock_bh(rt_hash_lock_addr(i));
@@ -789,11 +822,29 @@ static void rt_check_expire(void)
if (time_before_eq(jiffies, rth->u.dst.expires)) {
tmo >>= 1;
rthp = &rth->u.dst.rt_next;
+ /*
+ * Only bump our length if the hash
+ * inputs on entries n and n+1 are not
+ * the same, we only count entries on
+ * a chain with equal hash inputs once
+ * so that entries for different QOS
+ * levels, and other non-hash input
+ * attributes don't unfairly skew
+ * the length computation
+ */
+ if ((*rthp == NULL) ||
+ !compare_hash_inputs(&(*rthp)->fl,
+ &rth->fl))
+ length += ONE;
continue;
}
} else if (!rt_may_expire(rth, tmo, ip_rt_gc_timeout)) {
tmo >>= 1;
rthp = &rth->u.dst.rt_next;
+ if ((*rthp == NULL) ||
+ !compare_hash_inputs(&(*rthp)->fl,
+ &rth->fl))
+ length += ONE;
continue;
}
@@ -802,6 +853,15 @@ static void rt_check_expire(void)
rt_free(rth);
}
spin_unlock_bh(rt_hash_lock_addr(i));
+ sum += length;
+ sum2 += length*length;
+ }
+ if (samples) {
+ unsigned long avg = sum / samples;
+ unsigned long sd = int_sqrt(sum2 / samples - avg*avg);
+ rt_chain_length_max = max_t(unsigned long,
+ ip_rt_gc_elasticity,
+ (avg + 4*sd) >> FRACT_BITS);
}
rover = i;
}
@@ -851,6 +911,26 @@ static void rt_secret_rebuild(unsigned long __net)
mod_timer(&net->ipv4.rt_secret_timer, jiffies + ip_rt_secret_interval);
}
+static void rt_secret_rebuild_oneshot(struct net *net)
+{
+ del_timer_sync(&net->ipv4.rt_secret_timer);
+ rt_cache_invalidate(net);
+ if (ip_rt_secret_interval) {
+ net->ipv4.rt_secret_timer.expires += ip_rt_secret_interval;
+ add_timer(&net->ipv4.rt_secret_timer);
+ }
+}
+
+static void rt_emergency_hash_rebuild(struct net *net)
+{
+ if (net_ratelimit()) {
+ printk(KERN_WARNING "Route hash chain too long!\n");
+ printk(KERN_WARNING "Adjust your secret_interval!\n");
+ }
+
+ rt_secret_rebuild_oneshot(net);
+}
+
/*
Short description of GC goals.
@@ -989,6 +1069,7 @@ out: return 0;
static int rt_intern_hash(unsigned hash, struct rtable *rt, struct rtable **rp)
{
struct rtable *rth, **rthp;
+ struct rtable *rthi;
unsigned long now;
struct rtable *cand, **candp;
u32 min_score;
@@ -1002,7 +1083,13 @@ restart:
candp = NULL;
now = jiffies;
+ if (!rt_caching(dev_net(rt->u.dst.dev))) {
+ rt_drop(rt);
+ return 0;
+ }
+
rthp = &rt_hash_table[hash].chain;
+ rthi = NULL;
spin_lock_bh(rt_hash_lock_addr(hash));
while ((rth = *rthp) != NULL) {
@@ -1048,6 +1135,17 @@ restart:
chain_length++;
rthp = &rth->u.dst.rt_next;
+
+ /*
+ * check to see if the next entry in the chain
+ * contains the same hash input values as rt. If it does
+ * This is where we will insert into the list, instead of
+ * at the head. This groups entries that differ by aspects not
+ * relvant to the hash function together, which we use to adjust
+ * our chain length
+ */
+ if (*rthp && compare_hash_inputs(&(*rthp)->fl, &rt->fl))
+ rthi = rth;
}
if (cand) {
@@ -1061,6 +1159,16 @@ restart:
*candp = cand->u.dst.rt_next;
rt_free(cand);
}
+ } else {
+ if (chain_length > rt_chain_length_max) {
+ struct net *net = dev_net(rt->u.dst.dev);
+ int num = ++net->ipv4.current_rt_cache_rebuild_count;
+ if (!rt_caching(dev_net(rt->u.dst.dev))) {
+ printk(KERN_WARNING "%s: %d rebuilds is over limit, route caching disabled\n",
+ rt->u.dst.dev->name, num);
+ }
+ rt_emergency_hash_rebuild(dev_net(rt->u.dst.dev));
+ }
}
/* Try to bind route to arp only if it is output
@@ -1098,7 +1206,11 @@ restart:
}
}
- rt->u.dst.rt_next = rt_hash_table[hash].chain;
+ if (rthi)
+ rt->u.dst.rt_next = rthi->u.dst.rt_next;
+ else
+ rt->u.dst.rt_next = rt_hash_table[hash].chain;
+
#if RT_CACHE_DEBUG >= 2
if (rt->u.dst.rt_next) {
struct rtable *trt;
@@ -1114,7 +1226,11 @@ restart:
* previous writes to rt are comitted to memory
* before making rt visible to other CPUS.
*/
- rcu_assign_pointer(rt_hash_table[hash].chain, rt);
+ if (rthi)
+ rcu_assign_pointer(rthi->u.dst.rt_next, rt);
+ else
+ rcu_assign_pointer(rt_hash_table[hash].chain, rt);
+
spin_unlock_bh(rt_hash_lock_addr(hash));
*rp = rt;
return 0;
@@ -1217,6 +1333,9 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
|| ipv4_is_zeronet(new_gw))
goto reject_redirect;
+ if (!rt_caching(net))
+ goto reject_redirect;
+
if (!IN_DEV_SHARED_MEDIA(in_dev)) {
if (!inet_addr_onlink(in_dev, new_gw, old_gw))
goto reject_redirect;
@@ -2130,6 +2249,10 @@ int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr,
struct net *net;
net = dev_net(dev);
+
+ if (!rt_caching(net))
+ goto skip_cache;
+
tos &= IPTOS_RT_MASK;
hash = rt_hash(daddr, saddr, iif, rt_genid(net));
@@ -2154,6 +2277,7 @@ int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr,
}
rcu_read_unlock();
+skip_cache:
/* Multicast recognition logic is moved from route cache to here.
The problem was that too many Ethernet cards have broken/missing
hardware multicast filters :-( As result the host on multicasting
@@ -2539,6 +2663,9 @@ int __ip_route_output_key(struct net *net, struct rtable **rp,
unsigned hash;
struct rtable *rth;
+ if (!rt_caching(net))
+ goto slow_output;
+
hash = rt_hash(flp->fl4_dst, flp->fl4_src, flp->oif, rt_genid(net));
rcu_read_lock_bh();
@@ -2563,6 +2690,7 @@ int __ip_route_output_key(struct net *net, struct rtable **rp,
}
rcu_read_unlock_bh();
+slow_output:
return ip_route_output_slow(net, rp, flp);
}
@@ -795,6 +795,14 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "rt_cache_rebuild_count",
+ .data = &init_net.ipv4.sysctl_rt_cache_rebuild_count,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec
+ },
{ }
};
@@ -827,8 +835,12 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
&net->ipv4.sysctl_icmp_ratelimit;
table[5].data =
&net->ipv4.sysctl_icmp_ratemask;
+ table[6].data =
+ &net->ipv4.sysctl_rt_cache_rebuild_count;
}
+ net->ipv4.sysctl_rt_cache_rebuild_count = 4;
+
net->ipv4.ipv4_hdr = register_net_sysctl_table(net,
net_ipv4_ctl_path, table);
if (net->ipv4.ipv4_hdr == NULL)