inetpeer: remove AVL implementation in favor of RB tree
authorEric Dumazet <edumazet@google.com>
Mon, 17 Jul 2017 09:56:10 +0000 (02:56 -0700)
committerDavid S. Miller <davem@davemloft.net>
Mon, 17 Jul 2017 15:59:01 +0000 (08:59 -0700)
As discussed in Faro during Netfilter Workshop 2017, RB trees can be
used with RCU, using a seqlock.

Note that net/rxrpc/conn_service.c is already using this.

This patch converts inetpeer from AVL tree to RB tree, since it allows
to remove private AVL implementation in favor of shared RB code.

$ size net/ipv4/inetpeer.before net/ipv4/inetpeer.after
   text    data     bss     dec     hex filename
   3195      40     128    3363     d23 net/ipv4/inetpeer.before
   1562      24       0    1586     632 net/ipv4/inetpeer.after

The same technique can be used to speed up
net/netfilter/nft_set_rbtree.c (removing rwlock contention in fast path)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/inetpeer.h
net/ipv4/inetpeer.c

index f2a215fc78e4686f597c4041796663a7a463e73f..950ed182f62f6f2e359b8ead28d903b4c6dc877f 100644 (file)
@@ -33,18 +33,12 @@ struct inetpeer_addr {
 };
 
 struct inet_peer {
-       /* group together avl_left,avl_right,v4daddr to speedup lookups */
-       struct inet_peer __rcu  *avl_left, *avl_right;
+       struct rb_node          rb_node;
        struct inetpeer_addr    daddr;
-       __u32                   avl_height;
 
        u32                     metrics[RTAX_MAX];
        u32                     rate_tokens;    /* rate limiting for ICMP */
        unsigned long           rate_last;
-       union {
-               struct list_head        gc_list;
-               struct rcu_head     gc_rcu;
-       };
        /*
         * Once inet_peer is queued for deletion (refcnt == 0), following field
         * is not available: rid
@@ -55,7 +49,6 @@ struct inet_peer {
                        atomic_t                        rid;            /* Frag reception counter */
                };
                struct rcu_head         rcu;
-               struct inet_peer        *gc_next;
        };
 
        /* following fields might be frequently dirtied */
@@ -64,7 +57,7 @@ struct inet_peer {
 };
 
 struct inet_peer_base {
-       struct inet_peer __rcu  *root;
+       struct rb_root          rb_root;
        seqlock_t               lock;
        int                     total;
 };
index c5a117cc66198ca0fe9d49e1c15f3c3110a0d634..337ad41bb80a5fcd3db7ac674292c5b5d462982e 100644 (file)
@@ -33,7 +33,7 @@
  *  also be removed if the pool is overloaded i.e. if the total amount of
  *  entries is greater-or-equal than the threshold.
  *
- *  Node pool is organised as an AVL tree.
+ *  Node pool is organised as an RB tree.
  *  Such an implementation has been chosen not just for fun.  It's a way to
  *  prevent easy and efficient DoS attacks by creating hash collisions.  A huge
  *  amount of long living nodes in a single hash slot would significantly delay
@@ -45,7 +45,7 @@
  *      AND reference count being 0.
  *  3.  Global variable peer_total is modified under the pool lock.
  *  4.  struct inet_peer fields modification:
- *             avl_left, avl_right, avl_parent, avl_height: pool lock
+ *             rb_node: pool lock
  *             refcnt: atomically against modifications on other CPU;
  *                usually under some other lock to prevent node disappearing
  *             daddr: unchangeable
 
 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)
-#define peer_avl_empty_rcu ((struct inet_peer __rcu __force *)&peer_fake_node)
-static const struct inet_peer peer_fake_node = {
-       .avl_left       = peer_avl_empty_rcu,
-       .avl_right      = peer_avl_empty_rcu,
-       .avl_height     = 0
-};
-
 void inet_peer_base_init(struct inet_peer_base *bp)
 {
-       bp->root = peer_avl_empty_rcu;
+       bp->rb_root = RB_ROOT;
        seqlock_init(&bp->lock);
        bp->total = 0;
 }
 EXPORT_SYMBOL_GPL(inet_peer_base_init);
 
-#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */
+#define PEER_MAX_GC 32
 
 /* Exported for sysctl_net_ipv4.  */
 int inet_peer_threshold __read_mostly = 65536 + 128;   /* start to throw entries more
@@ -84,53 +69,6 @@ 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, *c;
-       struct 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();
-
-               c = rcu_dereference_protected(p->avl_left, 1);
-               if (c != peer_avl_empty) {
-                       list_add_tail(&c->gc_list, &list);
-                       p->avl_left = peer_avl_empty_rcu;
-               }
-
-               c = rcu_dereference_protected(p->avl_right, 1);
-               if (c != peer_avl_empty) {
-                       list_add_tail(&c->gc_list, &list);
-                       p->avl_right = peer_avl_empty_rcu;
-               }
-
-               n = list_entry(p->gc_list.next, struct inet_peer, gc_list);
-
-               if (refcount_read(&p->refcnt) == 1) {
-                       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)
 {
@@ -153,225 +91,62 @@ void __init inet_initpeers(void)
                        sizeof(struct inet_peer),
                        0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
                        NULL);
-
-       INIT_DEFERRABLE_WORK(&gc_work, inetpeer_gc_worker);
 }
 
-#define rcu_deref_locked(X, BASE)                              \
-       rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock))
-
-/*
- * Called with local BH disabled and the pool lock held.
- */
-#define lookup(_daddr, _stack, _base)                          \
-({                                                             \
-       struct inet_peer *u;                                    \
-       struct inet_peer __rcu **v;                             \
-                                                               \
-       stackptr = _stack;                                      \
-       *stackptr++ = &_base->root;                             \
-       for (u = rcu_deref_locked(_base->root, _base);          \
-            u != peer_avl_empty;) {                            \
-               int cmp = inetpeer_addr_cmp(_daddr, &u->daddr); \
-               if (cmp == 0)                                   \
-                       break;                                  \
-               if (cmp == -1)                                  \
-                       v = &u->avl_left;                       \
-               else                                            \
-                       v = &u->avl_right;                      \
-               *stackptr++ = v;                                \
-               u = rcu_deref_locked(*v, _base);                \
-       }                                                       \
-       u;                                                      \
-})
-
-/*
- * Called with rcu_read_lock()
- * Because we hold no lock against a writer, its quite possible we fall
- * in an endless loop.
- * But every pointer we follow is guaranteed to be valid thanks to RCU.
- * We exit from this function if number of links exceeds PEER_MAXDEPTH
- */
-static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr,
-                                   struct inet_peer_base *base)
+/* Called with rcu_read_lock() or base->lock held */
+static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
+                               struct inet_peer_base *base,
+                               unsigned int seq,
+                               struct inet_peer *gc_stack[],
+                               unsigned int *gc_cnt,
+                               struct rb_node **parent_p,
+                               struct rb_node ***pp_p)
 {
-       struct inet_peer *u = rcu_dereference(base->root);
-       int count = 0;
+       struct rb_node **pp, *parent;
+       struct inet_peer *p;
+
+       pp = &base->rb_root.rb_node;
+       parent = NULL;
+       while (*pp) {
+               int cmp;
 
-       while (u != peer_avl_empty) {
-               int cmp = inetpeer_addr_cmp(daddr, &u->daddr);
+               parent = rcu_dereference_raw(*pp);
+               p = rb_entry(parent, struct inet_peer, rb_node);
+               cmp = inetpeer_addr_cmp(daddr, &p->daddr);
                if (cmp == 0) {
-                       /* Before taking a reference, check if this entry was
-                        * deleted (refcnt=0)
-                        */
-                       if (!refcount_inc_not_zero(&u->refcnt)) {
-                               u = NULL;
-                       }
-                       return u;
+                       if (!refcount_inc_not_zero(&p->refcnt))
+                               break;
+                       return p;
+               }
+               if (gc_stack) {
+                       if (*gc_cnt < PEER_MAX_GC)
+                               gc_stack[(*gc_cnt)++] = p;
+               } else if (unlikely(read_seqretry(&base->lock, seq))) {
+                       break;
                }
                if (cmp == -1)
-                       u = rcu_dereference(u->avl_left);
+                       pp = &(*pp)->rb_left;
                else
-                       u = rcu_dereference(u->avl_right);
-               if (unlikely(++count == PEER_MAXDEPTH))
-                       break;
+                       pp = &(*pp)->rb_right;
        }
+       *parent_p = parent;
+       *pp_p = pp;
        return NULL;
 }
 
-/* Called with local BH disabled and the pool lock held. */
-#define lookup_rightempty(start, base)                         \
-({                                                             \
-       struct inet_peer *u;                                    \
-       struct inet_peer __rcu **v;                             \
-       *stackptr++ = &start->avl_left;                         \
-       v = &start->avl_left;                                   \
-       for (u = rcu_deref_locked(*v, base);                    \
-            u->avl_right != peer_avl_empty_rcu;) {             \
-               v = &u->avl_right;                              \
-               *stackptr++ = v;                                \
-               u = rcu_deref_locked(*v, base);                 \
-       }                                                       \
-       u;                                                      \
-})
-
-/* Called with local BH disabled and the pool lock held.
- * Variable names are the proof of operation correctness.
- * Look into mm/map_avl.c for more detail description of the ideas.
- */
-static void peer_avl_rebalance(struct inet_peer __rcu **stack[],
-                              struct inet_peer __rcu ***stackend,
-                              struct inet_peer_base *base)
-{
-       struct inet_peer __rcu **nodep;
-       struct inet_peer *node, *l, *r;
-       int lh, rh;
-
-       while (stackend > stack) {
-               nodep = *--stackend;
-               node = rcu_deref_locked(*nodep, base);
-               l = rcu_deref_locked(node->avl_left, base);
-               r = rcu_deref_locked(node->avl_right, base);
-               lh = node_height(l);
-               rh = node_height(r);
-               if (lh > rh + 1) { /* l: RH+2 */
-                       struct inet_peer *ll, *lr, *lrl, *lrr;
-                       int lrh;
-                       ll = rcu_deref_locked(l->avl_left, base);
-                       lr = rcu_deref_locked(l->avl_right, base);
-                       lrh = node_height(lr);
-                       if (lrh <= node_height(ll)) {   /* ll: RH+1 */
-                               RCU_INIT_POINTER(node->avl_left, lr);   /* lr: RH or RH+1 */
-                               RCU_INIT_POINTER(node->avl_right, r);   /* r: RH */
-                               node->avl_height = lrh + 1; /* RH+1 or RH+2 */
-                               RCU_INIT_POINTER(l->avl_left, ll);       /* ll: RH+1 */
-                               RCU_INIT_POINTER(l->avl_right, node);   /* node: RH+1 or RH+2 */
-                               l->avl_height = node->avl_height + 1;
-                               RCU_INIT_POINTER(*nodep, l);
-                       } else { /* ll: RH, lr: RH+1 */
-                               lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */
-                               lrr = rcu_deref_locked(lr->avl_right, base);/* lrr: RH or RH-1 */
-                               RCU_INIT_POINTER(node->avl_left, lrr);  /* lrr: RH or RH-1 */
-                               RCU_INIT_POINTER(node->avl_right, r);   /* r: RH */
-                               node->avl_height = rh + 1; /* node: RH+1 */
-                               RCU_INIT_POINTER(l->avl_left, ll);      /* ll: RH */
-                               RCU_INIT_POINTER(l->avl_right, lrl);    /* lrl: RH or RH-1 */
-                               l->avl_height = rh + 1; /* l: RH+1 */
-                               RCU_INIT_POINTER(lr->avl_left, l);      /* l: RH+1 */
-                               RCU_INIT_POINTER(lr->avl_right, node);  /* node: RH+1 */
-                               lr->avl_height = rh + 2;
-                               RCU_INIT_POINTER(*nodep, lr);
-                       }
-               } else if (rh > lh + 1) { /* r: LH+2 */
-                       struct inet_peer *rr, *rl, *rlr, *rll;
-                       int rlh;
-                       rr = rcu_deref_locked(r->avl_right, base);
-                       rl = rcu_deref_locked(r->avl_left, base);
-                       rlh = node_height(rl);
-                       if (rlh <= node_height(rr)) {   /* rr: LH+1 */
-                               RCU_INIT_POINTER(node->avl_right, rl);  /* rl: LH or LH+1 */
-                               RCU_INIT_POINTER(node->avl_left, l);    /* l: LH */
-                               node->avl_height = rlh + 1; /* LH+1 or LH+2 */
-                               RCU_INIT_POINTER(r->avl_right, rr);     /* rr: LH+1 */
-                               RCU_INIT_POINTER(r->avl_left, node);    /* node: LH+1 or LH+2 */
-                               r->avl_height = node->avl_height + 1;
-                               RCU_INIT_POINTER(*nodep, r);
-                       } else { /* rr: RH, rl: RH+1 */
-                               rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */
-                               rll = rcu_deref_locked(rl->avl_left, base);/* rll: LH or LH-1 */
-                               RCU_INIT_POINTER(node->avl_right, rll); /* rll: LH or LH-1 */
-                               RCU_INIT_POINTER(node->avl_left, l);    /* l: LH */
-                               node->avl_height = lh + 1; /* node: LH+1 */
-                               RCU_INIT_POINTER(r->avl_right, rr);     /* rr: LH */
-                               RCU_INIT_POINTER(r->avl_left, rlr);     /* rlr: LH or LH-1 */
-                               r->avl_height = lh + 1; /* r: LH+1 */
-                               RCU_INIT_POINTER(rl->avl_right, r);     /* r: LH+1 */
-                               RCU_INIT_POINTER(rl->avl_left, node);   /* node: LH+1 */
-                               rl->avl_height = lh + 2;
-                               RCU_INIT_POINTER(*nodep, rl);
-                       }
-               } else {
-                       node->avl_height = (lh > rh ? lh : rh) + 1;
-               }
-       }
-}
-
-/* Called with local BH disabled and the pool lock held. */
-#define link_to_pool(n, base)                                  \
-do {                                                           \
-       n->avl_height = 1;                                      \
-       n->avl_left = peer_avl_empty_rcu;                       \
-       n->avl_right = peer_avl_empty_rcu;                      \
-       /* lockless readers can catch us now */                 \
-       rcu_assign_pointer(**--stackptr, n);                    \
-       peer_avl_rebalance(stack, stackptr, base);              \
-} while (0)
-
 static void inetpeer_free_rcu(struct rcu_head *head)
 {
        kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu));
 }
 
-static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base,
-                            struct inet_peer __rcu **stack[PEER_MAXDEPTH])
-{
-       struct inet_peer __rcu ***stackptr, ***delp;
-
-       if (lookup(&p->daddr, stack, base) != p)
-               BUG();
-       delp = stackptr - 1; /* *delp[0] == p */
-       if (p->avl_left == peer_avl_empty_rcu) {
-               *delp[0] = p->avl_right;
-               --stackptr;
-       } else {
-               /* look for a node to insert instead of p */
-               struct inet_peer *t;
-               t = lookup_rightempty(p, base);
-               BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t);
-               **--stackptr = t->avl_left;
-               /* t is removed, t->daddr > x->daddr for any
-                * x in p->avl_left subtree.
-                * Put t in the old place of p. */
-               RCU_INIT_POINTER(*delp[0], t);
-               t->avl_left = p->avl_left;
-               t->avl_right = p->avl_right;
-               t->avl_height = p->avl_height;
-               BUG_ON(delp[1] != &p->avl_left);
-               delp[1] = &t->avl_left; /* was &p->avl_left */
-       }
-       peer_avl_rebalance(stack, stackptr, base);
-       base->total--;
-       call_rcu(&p->rcu, inetpeer_free_rcu);
-}
-
 /* perform garbage collect on all items stacked during a lookup */
-static int inet_peer_gc(struct inet_peer_base *base,
-                       struct inet_peer __rcu **stack[PEER_MAXDEPTH],
-                       struct inet_peer __rcu ***stackptr)
+static void inet_peer_gc(struct inet_peer_base *base,
+                        struct inet_peer *gc_stack[],
+                        unsigned int gc_cnt)
 {
-       struct inet_peer *p, *gchead = NULL;
+       struct inet_peer *p;
        __u32 delta, ttl;
-       int cnt = 0;
+       int i;
 
        if (base->total >= inet_peer_threshold)
                ttl = 0; /* be aggressive */
@@ -379,43 +154,38 @@ static int inet_peer_gc(struct inet_peer_base *base,
                ttl = inet_peer_maxttl
                                - (inet_peer_maxttl - inet_peer_minttl) / HZ *
                                        base->total / inet_peer_threshold * HZ;
-       stackptr--; /* last stack slot is peer_avl_empty */
-       while (stackptr > stack) {
-               stackptr--;
-               p = rcu_deref_locked(**stackptr, base);
-               if (refcount_read(&p->refcnt) == 1) {
-                       smp_rmb();
-                       delta = (__u32)jiffies - p->dtime;
-                       if (delta >= ttl && refcount_dec_if_one(&p->refcnt)) {
-                               p->gc_next = gchead;
-                               gchead = p;
-                       }
-               }
+       for (i = 0; i < gc_cnt; i++) {
+               p = gc_stack[i];
+               delta = (__u32)jiffies - p->dtime;
+               if (delta < ttl || !refcount_dec_if_one(&p->refcnt))
+                       gc_stack[i] = NULL;
        }
-       while ((p = gchead) != NULL) {
-               gchead = p->gc_next;
-               cnt++;
-               unlink_from_pool(p, base, stack);
+       for (i = 0; i < gc_cnt; i++) {
+               p = gc_stack[i];
+               if (p) {
+                       rb_erase(&p->rb_node, &base->rb_root);
+                       base->total--;
+                       call_rcu(&p->rcu, inetpeer_free_rcu);
+               }
        }
-       return cnt;
 }
 
 struct inet_peer *inet_getpeer(struct inet_peer_base *base,
                               const struct inetpeer_addr *daddr,
                               int create)
 {
-       struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr;
-       struct inet_peer *p;
-       unsigned int sequence;
-       int invalidated, gccnt = 0;
+       struct inet_peer *p, *gc_stack[PEER_MAX_GC];
+       struct rb_node **pp, *parent;
+       unsigned int gc_cnt, seq;
+       int invalidated;
 
        /* Attempt a lockless lookup first.
         * Because of a concurrent writer, we might not find an existing entry.
         */
        rcu_read_lock();
-       sequence = read_seqbegin(&base->lock);
-       p = lookup_rcu(daddr, base);
-       invalidated = read_seqretry(&base->lock, sequence);
+       seq = read_seqbegin(&base->lock);
+       p = lookup(daddr, base, seq, NULL, &gc_cnt, &parent, &pp);
+       invalidated = read_seqretry(&base->lock, seq);
        rcu_read_unlock();
 
        if (p)
@@ -428,36 +198,31 @@ struct inet_peer *inet_getpeer(struct inet_peer_base *base,
        /* retry an exact lookup, taking the lock before.
         * At least, nodes should be hot in our cache.
         */
+       parent = NULL;
        write_seqlock_bh(&base->lock);
-relookup:
-       p = lookup(daddr, stack, base);
-       if (p != peer_avl_empty) {
-               refcount_inc(&p->refcnt);
-               write_sequnlock_bh(&base->lock);
-               return p;
-       }
-       if (!gccnt) {
-               gccnt = inet_peer_gc(base, stack, stackptr);
-               if (gccnt && create)
-                       goto relookup;
-       }
-       p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL;
-       if (p) {
-               p->daddr = *daddr;
-               refcount_set(&p->refcnt, 2);
-               atomic_set(&p->rid, 0);
-               p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
-               p->rate_tokens = 0;
-               /* 60*HZ is arbitrary, but chosen enough high so that the first
-                * calculation of tokens is at its maximum.
-                */
-               p->rate_last = jiffies - 60*HZ;
-               INIT_LIST_HEAD(&p->gc_list);
 
-               /* Link the node. */
-               link_to_pool(p, base);
-               base->total++;
+       gc_cnt = 0;
+       p = lookup(daddr, base, seq, gc_stack, &gc_cnt, &parent, &pp);
+       if (!p && create) {
+               p = kmem_cache_alloc(peer_cachep, GFP_ATOMIC);
+               if (p) {
+                       p->daddr = *daddr;
+                       refcount_set(&p->refcnt, 2);
+                       atomic_set(&p->rid, 0);
+                       p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
+                       p->rate_tokens = 0;
+                       /* 60*HZ is arbitrary, but chosen enough high so that the first
+                        * calculation of tokens is at its maximum.
+                        */
+                       p->rate_last = jiffies - 60*HZ;
+
+                       rb_link_node(&p->rb_node, parent, pp);
+                       rb_insert_color(&p->rb_node, &base->rb_root);
+                       base->total++;
+               }
        }
+       if (gc_cnt)
+               inet_peer_gc(base, gc_stack, gc_cnt);
        write_sequnlock_bh(&base->lock);
 
        return p;
@@ -467,8 +232,9 @@ EXPORT_SYMBOL_GPL(inet_getpeer);
 void inet_putpeer(struct inet_peer *p)
 {
        p->dtime = (__u32)jiffies;
-       smp_mb__before_atomic();
-       refcount_dec(&p->refcnt);
+
+       if (refcount_dec_and_test(&p->refcnt))
+               call_rcu(&p->rcu, inetpeer_free_rcu);
 }
 EXPORT_SYMBOL_GPL(inet_putpeer);
 
@@ -513,30 +279,16 @@ bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
 }
 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(struct inet_peer_base *base)
 {
-       struct inet_peer *root;
-
-       write_seqlock_bh(&base->lock);
+       struct inet_peer *p, *n;
 
-       root = rcu_deref_locked(base->root, base);
-       if (root != peer_avl_empty) {
-               base->root = peer_avl_empty_rcu;
-               base->total = 0;
-               call_rcu(&root->gc_rcu, inetpeer_inval_rcu);
+       rbtree_postorder_for_each_entry_safe(p, n, &base->rb_root, rb_node) {
+               inet_putpeer(p);
+               cond_resched();
        }
 
-       write_sequnlock_bh(&base->lock);
+       base->rb_root = RB_ROOT;
+       base->total = 0;
 }
 EXPORT_SYMBOL(inetpeer_invalidate_tree);