inetpeer: Invalidate the inetpeer tree along with the routing cache

We initialize the routing metrics with the values cached on the
inetpeer in rt_init_metrics(). So if we have the metrics cached on the
inetpeer, we ignore the user configured fib_metrics.

To fix this issue, we replace the old tree with a fresh initialized
inet_peer_base. The old tree is removed later with a delayed work queue.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 83 insertions, 1 deletions

diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index 06b795dd5906..ff04a33acf00 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -41,6 +41,7 @@ struct inet_peer {
         u32                     pmtu_orig;
         u32                     pmtu_learned;
         struct inetpeer_addr_base redirect_learned;
+        struct list_head        gc_list;
         /*
          * Once inet_peer is queued for deletion (refcnt == -1), following fields
          * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
@@ -96,6 +97,8 @@ static inline struct inet_peer *inet_getpeer_v6(const struct in6_addr *v6daddr,
 extern void inet_putpeer(struct inet_peer *p);
 extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
 
+extern void inetpeer_invalidate_tree(int family);
+
 /*
  * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
  * tcp_ts_stamp if no refcount is taken on inet_peer
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index bf4a9c4808e1..deea2e96b7f2 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/net.h>
+#include <linux/workqueue.h>
 #include <net/ip.h>
 #include <net/inetpeer.h>
 #include <net/secure_seq.h>
@@ -66,6 +67,11 @@
 
 static struct kmem_cache *peer_cachep __read_mostly;
 
+static LIST_HEAD(gc_list);
+static const int gc_delay = 60 * HZ;
+static struct delayed_work gc_work;
+static DEFINE_SPINLOCK(gc_lock);
+
 #define node_height(x) x->avl_height
 
 #define peer_avl_empty ((struct inet_peer *)&peer_fake_node)
@@ -102,6 +108,50 @@ int inet_peer_threshold __read_mostly = 65536 + 128;	/* start to throw entries m
 int inet_peer_minttl __read_mostly = 120 * HZ;  /* TTL under high load: 120 sec */
 int inet_peer_maxttl __read_mostly = 10 * 60 * HZ;      /* usual time to live: 10 min */
 
+static void inetpeer_gc_worker(struct work_struct *work)
+{
+        struct inet_peer *p, *n;
+        LIST_HEAD(list);
+
+        spin_lock_bh(&gc_lock);
+        list_replace_init(&gc_list, &list);
+        spin_unlock_bh(&gc_lock);
+
+        if (list_empty(&list))
+                return;
+
+        list_for_each_entry_safe(p, n, &list, gc_list) {
+
+                if(need_resched())
+                        cond_resched();
+
+                if (p->avl_left != peer_avl_empty) {
+                        list_add_tail(&p->avl_left->gc_list, &list);
+                        p->avl_left = peer_avl_empty;
+                }
+
+                if (p->avl_right != peer_avl_empty) {
+                        list_add_tail(&p->avl_right->gc_list, &list);
+                        p->avl_right = peer_avl_empty;
+                }
+
+                n = list_entry(p->gc_list.next, struct inet_peer, gc_list);
+
+                if (!atomic_read(&p->refcnt)) {
+                        list_del(&p->gc_list);
+                        kmem_cache_free(peer_cachep, p);
+                }
+        }
+
+        if (list_empty(&list))
+                return;
+
+        spin_lock_bh(&gc_lock);
+        list_splice(&list, &gc_list);
+        spin_unlock_bh(&gc_lock);
+
+        schedule_delayed_work(&gc_work, gc_delay);
+}
 
 /* Called from ip_output.c:ip_init  */
 void __init inet_initpeers(void)
@@ -126,6 +176,7 @@ void __init inet_initpeers(void)
                         0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
                         NULL);
 
+        INIT_DELAYED_WORK_DEFERRABLE(&gc_work, inetpeer_gc_worker);
 }
 
 static int addr_compare(const struct inetpeer_addr *a,
@@ -449,7 +500,7 @@ relookup:
                 p->pmtu_orig = 0;
                 p->redirect_genid = 0;
                 memset(&p->redirect_learned, 0, sizeof(p->redirect_learned));
-
+                INIT_LIST_HEAD(&p->gc_list);
 
                 /* Link the node. */
                 link_to_pool(p, base);
@@ -509,3 +560,30 @@ bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
         return rc;
 }
 EXPORT_SYMBOL(inet_peer_xrlim_allow);
+
+void inetpeer_invalidate_tree(int family)
+{
+        struct inet_peer *old, *new, *prev;
+        struct inet_peer_base *base = family_to_base(family);
+
+        write_seqlock_bh(&base->lock);
+
+        old = base->root;
+        if (old == peer_avl_empty_rcu)
+                goto out;
+
+        new = peer_avl_empty_rcu;
+
+        prev = cmpxchg(&base->root, old, new);
+        if (prev == old) {
+                base->total = 0;
+                spin_lock(&gc_lock);
+                list_add_tail(&prev->gc_list, &gc_list);
+                spin_unlock(&gc_lock);
+                schedule_delayed_work(&gc_work, gc_delay);
+        }
+
+out:
+        write_sequnlock_bh(&base->lock);
+}
+EXPORT_SYMBOL(inetpeer_invalidate_tree);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index bcacf54e5418..23ce0c1287ab 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -938,6 +938,7 @@ static void rt_cache_invalidate(struct net *net)
         get_random_bytes(&shuffle, sizeof(shuffle));
         atomic_add(shuffle + 1U, &net->ipv4.rt_genid);
         redirect_genid++;
+        inetpeer_invalidate_tree(AF_INET);
 }
 
 /*