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ipv4: remove ip_rt_secret timer (v4)
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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>
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Neil Horman authored and David S. Miller committed May 8, 2010
1 parent e0e3328 commit 3ee9437
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Showing 3 changed files with 8 additions and 102 deletions.
1 change: 0 additions & 1 deletion include/net/netns/ipv4.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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1 change: 0 additions & 1 deletion kernel/sysctl_binary.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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" },
{}
};

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108 changes: 8 additions & 100 deletions net/ipv4/route.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
}

/*
Expand Down Expand Up @@ -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",
Expand Down Expand Up @@ -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,
},
{ }
};

Expand Down Expand Up @@ -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,
};


Expand Down Expand Up @@ -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
Expand All @@ -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;
}

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