[PATCH net-next 3/3] ipv6: per netns FIB garbage collection

From: Michal Kubecek
Date: Fri Mar 04 2016 - 05:59:44 EST


One of our customers observed issues with FIB6 garbage collectors
running in different network namespaces blocking each other, resulting
in soft lockups (fib6_run_gc() initiated from timer runs always in
forced mode).

Now that FIB6 walkers are separated per namespace, there is no more need
for instances of fib6_run_gc() in different namespaces blocking each
other. There is still a call to icmp6_dst_gc() which operates on shared
data but this function is protected by its own shared lock.

Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
---
include/net/netns/ipv6.h | 1 +
net/ipv6/ip6_fib.c | 9 ++++-----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index f0109b973648..10d0848f5b8a 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -61,6 +61,7 @@ struct netns_ipv6 {
struct list_head fib6_walkers;
struct dst_ops ip6_dst_ops;
rwlock_t fib6_walker_lock;
+ spinlock_t fib6_gc_lock;
unsigned int ip6_rt_gc_expire;
unsigned long ip6_rt_last_gc;
#ifdef CONFIG_IPV6_MULTIPLE_TABLES
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index af8a0fb39eda..5145841612b3 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1776,16 +1776,14 @@ static int fib6_age(struct rt6_info *rt, void *arg)
return 0;
}

-static DEFINE_SPINLOCK(fib6_gc_lock);
-
void fib6_run_gc(unsigned long expires, struct net *net, bool force)
{
struct fib6_gc_args gc_args;
unsigned long now;

if (force) {
- spin_lock_bh(&fib6_gc_lock);
- } else if (!spin_trylock_bh(&fib6_gc_lock)) {
+ spin_lock_bh(&net->ipv6.fib6_gc_lock);
+ } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
return;
}
@@ -1804,7 +1802,7 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
+ net->ipv6.sysctl.ip6_rt_gc_interval));
else
del_timer(&net->ipv6.ip6_fib_timer);
- spin_unlock_bh(&fib6_gc_lock);
+ spin_unlock_bh(&net->ipv6.fib6_gc_lock);
}

static void fib6_gc_timer_cb(unsigned long arg)
@@ -1816,6 +1814,7 @@ static int __net_init fib6_net_init(struct net *net)
{
size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;

+ spin_lock_init(&net->ipv6.fib6_gc_lock);
rwlock_init(&net->ipv6.fib6_walker_lock);
INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
--
2.7.2