inet: remove (struct uncached_list)->quarantine

This list is used to tranfert dst that are handled by
rt_flush_dev() and rt6_uncached_list_flush_dev() out
of the per-cpu lists.

But quarantine list is not used later.

If we simply use list_del_init(&rt->dst.rt_uncached),
this also removes the dst from per-cpu list.

This patch also makes the future calls to rt_del_uncached_list()
and rt6_uncached_list_del() faster, because no spinlock
acquisition is needed anymore.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240604165150.726382-1-edumazet@google.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv4/route.c

@@ -1481,7 +1481,6 @@ static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
 struct uncached_list {
 	spinlock_t		lock;
 	struct list_head	head;
-	struct list_head	quarantine;
 };
 
 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
@@ -1532,7 +1531,7 @@ void rt_flush_dev(struct net_device *dev)
 			rt->dst.dev = blackhole_netdev;
 			netdev_ref_replace(dev, blackhole_netdev,
 					   &rt->dst.dev_tracker, GFP_ATOMIC);
-			list_move(&rt->dst.rt_uncached, &ul->quarantine);
+			list_del_init(&rt->dst.rt_uncached);
 		}
 		spin_unlock_bh(&ul->lock);
 	}
@@ -3661,7 +3660,6 @@ int __init ip_rt_init(void)
 		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
 
 		INIT_LIST_HEAD(&ul->head);
-		INIT_LIST_HEAD(&ul->quarantine);
 		spin_lock_init(&ul->lock);
 	}
 #ifdef CONFIG_IP_ROUTE_CLASSID

net/ipv6/route.c

@@ -131,7 +131,6 @@ 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);
@@ -189,8 +188,7 @@ static void rt6_uncached_list_flush_dev(struct net_device *dev)
 				handled = true;
 			}
 			if (handled)
-				list_move(&rt->dst.rt_uncached,
-					  &ul->quarantine);
+				list_del_init(&rt->dst.rt_uncached);
 		}
 		spin_unlock_bh(&ul->lock);
 	}
@@ -6755,7 +6753,6 @@ 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);
 	}