ipv4: remove ip_rt_secret timer (v4)

A while back there was a discussion regarding the rt_secret_interval timer.
Given that we've had the ability to do emergency route cache rebuilds for awhile
now, based on a statistical analysis of the various hash chain lengths in the
cache, the use of the flush timer is somewhat redundant.  This patch removes the
rt_secret_interval sysctl, allowing us to rely solely on the statistical
analysis mechanism to determine the need for route cache flushes.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index ae07fee..d68c3f1 100644 (file)
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -55,7 +55,6 @@ struct netns_ipv4 {
        int sysctl_rt_cache_rebuild_count;
        int current_rt_cache_rebuild_count;
 
-       struct timer_list rt_secret_timer;
        atomic_t rt_genid;
 
 #ifdef CONFIG_IP_MROUTE

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 5903057..937d31d 100644 (file)
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -224,7 +224,6 @@ static const struct bin_table bin_net_ipv4_route_table[] = {
        { CTL_INT,      NET_IPV4_ROUTE_MTU_EXPIRES,             "mtu_expires" },
        { CTL_INT,      NET_IPV4_ROUTE_MIN_PMTU,                "min_pmtu" },
        { CTL_INT,      NET_IPV4_ROUTE_MIN_ADVMSS,              "min_adv_mss" },
-       { CTL_INT,      NET_IPV4_ROUTE_SECRET_INTERVAL,         "secret_interval" },
        {}
 };
 

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a947428..dea3f92 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -129,7 +129,6 @@ static int ip_rt_gc_elasticity __read_mostly        = 8;
 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 struct delayed_work expires_work;
@@ -918,32 +917,11 @@ void rt_cache_flush_batch(void)
        rt_do_flush(!in_softirq());
 }
 
-/*
- * We change rt_genid and let gc do the cleanup
- */
-static void rt_secret_rebuild(unsigned long __net)
-{
-       struct net *net = (struct net *)__net;
-       rt_cache_invalidate(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)
-               mod_timer(&net->ipv4.rt_secret_timer, jiffies + ip_rt_secret_interval);
-}
-
 static void rt_emergency_hash_rebuild(struct net *net)
 {
-       if (net_ratelimit()) {
+       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);
+       rt_cache_invalidate(net);
 }
 
 /*
@@ -3101,48 +3079,6 @@ static int ipv4_sysctl_rtcache_flush(ctl_table *__ctl, int write,
        return -EINVAL;
 }
 
-static void rt_secret_reschedule(int old)
-{
-       struct net *net;
-       int new = ip_rt_secret_interval;
-       int diff = new - old;
-
-       if (!diff)
-               return;
-
-       rtnl_lock();
-       for_each_net(net) {
-               int deleted = del_timer_sync(&net->ipv4.rt_secret_timer);
-               long time;
-
-               if (!new)
-                       continue;
-
-               if (deleted) {
-                       time = net->ipv4.rt_secret_timer.expires - jiffies;
-
-                       if (time <= 0 || (time += diff) <= 0)
-                               time = 0;
-               } else
-                       time = new;
-
-               mod_timer(&net->ipv4.rt_secret_timer, jiffies + time);
-       }
-       rtnl_unlock();
-}
-
-static int ipv4_sysctl_rt_secret_interval(ctl_table *ctl, int write,
-                                         void __user *buffer, size_t *lenp,
-                                         loff_t *ppos)
-{
-       int old = ip_rt_secret_interval;
-       int ret = proc_dointvec_jiffies(ctl, write, buffer, lenp, ppos);
-
-       rt_secret_reschedule(old);
-
-       return ret;
-}
-
 static ctl_table ipv4_route_table[] = {
        {
                .procname       = "gc_thresh",
@@ -3251,13 +3187,6 @@ static ctl_table ipv4_route_table[] = {
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
-       {
-               .procname       = "secret_interval",
-               .data           = &ip_rt_secret_interval,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = ipv4_sysctl_rt_secret_interval,
-       },
        { }
 };
 
@@ -3336,34 +3265,15 @@ static __net_initdata struct pernet_operations sysctl_route_ops = {
 };
 #endif
 
-
-static __net_init int rt_secret_timer_init(struct net *net)
+static __net_init int rt_genid_init(struct net *net)
 {
-       atomic_set(&net->ipv4.rt_genid,
-                       (int) ((num_physpages ^ (num_physpages>>8)) ^
-                       (jiffies ^ (jiffies >> 7))));
-
-       net->ipv4.rt_secret_timer.function = rt_secret_rebuild;
-       net->ipv4.rt_secret_timer.data = (unsigned long)net;
-       init_timer_deferrable(&net->ipv4.rt_secret_timer);
-
-       if (ip_rt_secret_interval) {
-               net->ipv4.rt_secret_timer.expires =
-                       jiffies + net_random() % ip_rt_secret_interval +
-                       ip_rt_secret_interval;
-               add_timer(&net->ipv4.rt_secret_timer);
-       }
+       get_random_bytes(&net->ipv4.rt_genid,
+                        sizeof(net->ipv4.rt_genid));
        return 0;
 }
 
-static __net_exit void rt_secret_timer_exit(struct net *net)
-{
-       del_timer_sync(&net->ipv4.rt_secret_timer);
-}
-
-static __net_initdata struct pernet_operations rt_secret_timer_ops = {
-       .init = rt_secret_timer_init,
-       .exit = rt_secret_timer_exit,
+static __net_initdata struct pernet_operations rt_genid_ops = {
+       .init = rt_genid_init,
 };
 
 
@@ -3424,9 +3334,6 @@ int __init ip_rt_init(void)
        schedule_delayed_work(&expires_work,
                net_random() % ip_rt_gc_interval + ip_rt_gc_interval);
 
-       if (register_pernet_subsys(&rt_secret_timer_ops))
-               printk(KERN_ERR "Unable to setup rt_secret_timer\n");
-
        if (ip_rt_proc_init())
                printk(KERN_ERR "Unable to create route proc files\n");
 #ifdef CONFIG_XFRM
@@ -3438,6 +3345,7 @@ int __init ip_rt_init(void)
 #ifdef CONFIG_SYSCTL
        register_pernet_subsys(&sysctl_route_ops);
 #endif
+       register_pernet_subsys(&rt_genid_ops);
        return rc;
 }