inetpeer: fix a race in inetpeer_gc_worker()

[pandora-kernel.git] / net / ipv4 / inetpeer.c

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 86f13c6..552e4f8 100644 (file)
--- 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,
@@ -448,7 +499,7 @@ relookup:
                p->pmtu_expires = 0;
                p->pmtu_orig = 0;
                memset(&p->redirect_learned, 0, sizeof(p->redirect_learned));
-
+               INIT_LIST_HEAD(&p->gc_list);
 
                /* Link the node. */
                link_to_pool(p, base);
@@ -508,3 +559,38 @@ bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
        return rc;
 }
 EXPORT_SYMBOL(inet_peer_xrlim_allow);
+
+static void inetpeer_inval_rcu(struct rcu_head *head)
+{
+       struct inet_peer *p = container_of(head, struct inet_peer, gc_rcu);
+
+       spin_lock_bh(&gc_lock);
+       list_add_tail(&p->gc_list, &gc_list);
+       spin_unlock_bh(&gc_lock);
+
+       schedule_delayed_work(&gc_work, gc_delay);
+}
+
+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;
+               call_rcu(&prev->gc_rcu, inetpeer_inval_rcu);
+       }
+
+out:
+       write_sequnlock_bh(&base->lock);
+}
+EXPORT_SYMBOL(inetpeer_invalidate_tree);