ipv6: add (struct uncached_list)->quarantine list

This is an optimization to keep the per-cpu lists as short as possible:

Whenever rt6_uncached_list_flush_dev() changes one rt6_info
matching the disappearing device, it can can transfer the object
to a quarantine list, waiting for a final rt6_uncached_list_del().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index b04aaf13e41eb962975c025c78aac77e950ae796..46c7a1b360753ca1c61e5a4be174d582353848ab 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -130,6 +130,7 @@ static struct fib6_info *rt6_get_route_info(struct net *net,
 struct uncached_list {
        spinlock_t              lock;
        struct list_head        head;
+       struct list_head        quarantine;
 };
 
 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt6_uncached_list);
@@ -151,7 +152,7 @@ void rt6_uncached_list_del(struct rt6_info *rt)
                struct uncached_list *ul = rt->rt6i_uncached_list;
 
                spin_lock_bh(&ul->lock);
-               list_del(&rt->rt6i_uncached);
+               list_del_init(&rt->rt6i_uncached);
                spin_unlock_bh(&ul->lock);
        }
 }
@@ -162,16 +163,21 @@ static void rt6_uncached_list_flush_dev(struct net_device *dev)
 
        for_each_possible_cpu(cpu) {
                struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
-               struct rt6_info *rt;
+               struct rt6_info *rt, *safe;
+
+               if (list_empty(&ul->head))
+                       continue;
 
                spin_lock_bh(&ul->lock);
-               list_for_each_entry(rt, &ul->head, rt6i_uncached) {
+               list_for_each_entry_safe(rt, safe, &ul->head, rt6i_uncached) {
                        struct inet6_dev *rt_idev = rt->rt6i_idev;
                        struct net_device *rt_dev = rt->dst.dev;
+                       bool handled = false;
 
                        if (rt_idev->dev == dev) {
                                rt->rt6i_idev = in6_dev_get(blackhole_netdev);
                                in6_dev_put(rt_idev);
+                               handled = true;
                        }
 
                        if (rt_dev == dev) {
@@ -179,7 +185,11 @@ static void rt6_uncached_list_flush_dev(struct net_device *dev)
                                dev_replace_track(rt_dev, blackhole_netdev,
                                                  &rt->dst.dev_tracker,
                                                  GFP_ATOMIC);
+                               handled = true;
                        }
+                       if (handled)
+                               list_move(&rt->rt6i_uncached,
+                                         &ul->quarantine);
                }
                spin_unlock_bh(&ul->lock);
        }
@@ -6727,6 +6737,7 @@ int __init ip6_route_init(void)
                struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
 
                INIT_LIST_HEAD(&ul->head);
+               INIT_LIST_HEAD(&ul->quarantine);
                spin_lock_init(&ul->lock);
        }