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>

1 files changed, 8 insertions, 100 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a947428ef0ae..dea3f9264250 100644
--- 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;
 }