This routine checks for the existence of a given entry
in the hash table and inserts the new one if needed.

The ->equal callback is used to compare two frag_queue-s
together, but this one is temporary and will be removed
later. The netfilter code and the ipv6 one use the same
routine to compare frags.

The inet_frag_intern() always returns non-NULL pointer,
so convert the inet_frag_queue into protocol specific
one (with the container_of) without any checks.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 911c2cd..133e187 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -41,6 +41,8 @@ struct inet_frags {
 	unsigned int		(*hashfn)(struct inet_frag_queue *);
 	void			(*destructor)(struct inet_frag_queue *);
 	void			(*skb_free)(struct sk_buff *);
+	int			(*equal)(struct inet_frag_queue *q1,
+					 struct inet_frag_queue *q2);
 };
 
 void inet_frags_init(struct inet_frags *);
@@ -50,6 +52,8 @@ void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
 void inet_frag_destroy(struct inet_frag_queue *q,
 				struct inet_frags *f, int *work);
 int inet_frag_evictor(struct inet_frags *f);
+struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *q,
+		struct inet_frags *f, unsigned int hash);
 
 static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
 {
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index cc796cb..ff12697 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -377,6 +377,9 @@ static inline int ipv6_prefix_equal(const struct in6_addr *a1,
 				   prefixlen);
 }
 
+struct inet_frag_queue;
+int ip6_frag_equal(struct inet_frag_queue *q1, struct inet_frag_queue *q2);
+
 static inline int ipv6_addr_any(const struct in6_addr *a)
 {
 	return ((a->s6_addr32[0] | a->s6_addr32[1] | 
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 484cf51..15054eb 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -172,3 +172,40 @@ int inet_frag_evictor(struct inet_frags *f)
 	return evicted;
 }
 EXPORT_SYMBOL(inet_frag_evictor);
+
+struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *qp_in,
+		struct inet_frags *f, unsigned int hash)
+{
+	struct inet_frag_queue *qp;
+#ifdef CONFIG_SMP
+	struct hlist_node *n;
+#endif
+
+	write_lock(&f->lock);
+#ifdef CONFIG_SMP
+	/* With SMP race we have to recheck hash table, because
+	 * such entry could be created on other cpu, while we
+	 * promoted read lock to write lock.
+	 */
+	hlist_for_each_entry(qp, n, &f->hash[hash], list) {
+		if (f->equal(qp, qp_in)) {
+			atomic_inc(&qp->refcnt);
+			write_unlock(&f->lock);
+			qp_in->last_in |= COMPLETE;
+			inet_frag_put(qp_in, f);
+			return qp;
+		}
+	}
+#endif
+	qp = qp_in;
+	if (!mod_timer(&qp->timer, jiffies + f->ctl->timeout))
+		atomic_inc(&qp->refcnt);
+
+	atomic_inc(&qp->refcnt);
+	hlist_add_head(&qp->list, &f->hash[hash]);
+	list_add_tail(&qp->lru_list, &f->lru_list);
+	f->nqueues++;
+	write_unlock(&f->lock);
+	return qp;
+}
+EXPORT_SYMBOL(inet_frag_intern);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index d12a18b..4b1bbbe 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -123,6 +123,20 @@ static unsigned int ip4_hashfn(struct inet_frag_queue *q)
 	return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol);
 }
 
+static int ip4_frag_equal(struct inet_frag_queue *q1,
+		struct inet_frag_queue *q2)
+{
+	struct ipq *qp1, *qp2;
+
+	qp1 = container_of(q1, struct ipq, q);
+	qp2 = container_of(q2, struct ipq, q);
+	return (qp1->id == qp2->id &&
+			qp1->saddr == qp2->saddr &&
+			qp1->daddr == qp2->daddr &&
+			qp1->protocol == qp2->protocol &&
+			qp1->user == qp2->user);
+}
+
 /* Memory Tracking Functions. */
 static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work)
 {
@@ -214,43 +228,10 @@ out:
 
 static struct ipq *ip_frag_intern(struct ipq *qp_in, unsigned int hash)
 {
-	struct ipq *qp;
-#ifdef CONFIG_SMP
-	struct hlist_node *n;
-#endif
+	struct inet_frag_queue *q;
 
-	write_lock(&ip4_frags.lock);
-#ifdef CONFIG_SMP
-	/* With SMP race we have to recheck hash table, because
-	 * such entry could be created on other cpu, while we
-	 * promoted read lock to write lock.
-	 */
-	hlist_for_each_entry(qp, n, &ip4_frags.hash[hash], q.list) {
-		if (qp->id == qp_in->id		&&
-		    qp->saddr == qp_in->saddr	&&
-		    qp->daddr == qp_in->daddr	&&
-		    qp->protocol == qp_in->protocol &&
-		    qp->user == qp_in->user) {
-			atomic_inc(&qp->q.refcnt);
-			write_unlock(&ip4_frags.lock);
-			qp_in->q.last_in |= COMPLETE;
-			ipq_put(qp_in);
-			return qp;
-		}
-	}
-#endif
-	qp = qp_in;
-
-	if (!mod_timer(&qp->q.timer, jiffies + ip4_frags_ctl.timeout))
-		atomic_inc(&qp->q.refcnt);
-
-	atomic_inc(&qp->q.refcnt);
-	hlist_add_head(&qp->q.list, &ip4_frags.hash[hash]);
-	INIT_LIST_HEAD(&qp->q.lru_list);
-	list_add_tail(&qp->q.lru_list, &ip4_frags.lru_list);
-	ip4_frags.nqueues++;
-	write_unlock(&ip4_frags.lock);
-	return qp;
+	q = inet_frag_intern(&qp_in->q, &ip4_frags, hash);
+	return container_of(q, struct ipq, q);
 }
 
 /* Add an entry to the 'ipq' queue for a newly received IP datagram. */
@@ -671,6 +652,7 @@ void __init ipfrag_init(void)
 	ip4_frags.destructor = ip4_frag_free;
 	ip4_frags.skb_free = NULL;
 	ip4_frags.qsize = sizeof(struct ipq);
+	ip4_frags.equal = ip4_frag_equal;
 	inet_frags_init(&ip4_frags);
 }
 
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 726fafd..d7dc444 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -187,37 +187,10 @@ out:
 static struct nf_ct_frag6_queue *nf_ct_frag6_intern(unsigned int hash,
 					  struct nf_ct_frag6_queue *fq_in)
 {
-	struct nf_ct_frag6_queue *fq;
-#ifdef CONFIG_SMP
-	struct hlist_node *n;
-#endif
-
-	write_lock(&nf_frags.lock);
-#ifdef CONFIG_SMP
-	hlist_for_each_entry(fq, n, &nf_frags.hash[hash], q.list) {
-		if (fq->id == fq_in->id &&
-		    ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
-		    ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
-			atomic_inc(&fq->q.refcnt);
-			write_unlock(&nf_frags.lock);
-			fq_in->q.last_in |= COMPLETE;
-			fq_put(fq_in);
-			return fq;
-		}
-	}
-#endif
-	fq = fq_in;
+	struct inet_frag_queue *q;
 
-	if (!mod_timer(&fq->q.timer, jiffies + nf_frags_ctl.timeout))
-		atomic_inc(&fq->q.refcnt);
-
-	atomic_inc(&fq->q.refcnt);
-	hlist_add_head(&fq->q.list, &nf_frags.hash[hash]);
-	INIT_LIST_HEAD(&fq->q.lru_list);
-	list_add_tail(&fq->q.lru_list, &nf_frags.lru_list);
-	nf_frags.nqueues++;
-	write_unlock(&nf_frags.lock);
-	return fq;
+	q = inet_frag_intern(&fq_in->q, &nf_frags, hash);
+	return container_of(q, struct nf_ct_frag6_queue, q);
 }
 
 
@@ -752,6 +725,7 @@ int nf_ct_frag6_init(void)
 	nf_frags.destructor = nf_frag_free;
 	nf_frags.skb_free = nf_skb_free;
 	nf_frags.qsize = sizeof(struct nf_ct_frag6_queue);
+	nf_frags.equal = ip6_frag_equal;
 	inet_frags_init(&nf_frags);
 
 	return 0;
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 0a1bf43..73ea204 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -143,6 +143,18 @@ static unsigned int ip6_hashfn(struct inet_frag_queue *q)
 	return ip6qhashfn(fq->id, &fq->saddr, &fq->daddr);
 }
 
+int ip6_frag_equal(struct inet_frag_queue *q1, struct inet_frag_queue *q2)
+{
+	struct frag_queue *fq1, *fq2;
+
+	fq1 = container_of(q1, struct frag_queue, q);
+	fq2 = container_of(q2, struct frag_queue, q);
+	return (fq1->id == fq2->id &&
+			ipv6_addr_equal(&fq2->saddr, &fq1->saddr) &&
+			ipv6_addr_equal(&fq2->daddr, &fq1->daddr));
+}
+EXPORT_SYMBOL(ip6_frag_equal);
+
 /* Memory Tracking Functions. */
 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 {
@@ -236,37 +248,10 @@ out:
 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in,
 		unsigned int hash)
 {
-	struct frag_queue *fq;
-#ifdef CONFIG_SMP
-	struct hlist_node *n;
-#endif
-
-	write_lock(&ip6_frags.lock);
-#ifdef CONFIG_SMP
-	hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
-		if (fq->id == fq_in->id &&
-		    ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
-		    ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
-			atomic_inc(&fq->q.refcnt);
-			write_unlock(&ip6_frags.lock);
-			fq_in->q.last_in |= COMPLETE;
-			fq_put(fq_in);
-			return fq;
-		}
-	}
-#endif
-	fq = fq_in;
-
-	if (!mod_timer(&fq->q.timer, jiffies + ip6_frags_ctl.timeout))
-		atomic_inc(&fq->q.refcnt);
+	struct inet_frag_queue *q;
 
-	atomic_inc(&fq->q.refcnt);
-	hlist_add_head(&fq->q.list, &ip6_frags.hash[hash]);
-	INIT_LIST_HEAD(&fq->q.lru_list);
-	list_add_tail(&fq->q.lru_list, &ip6_frags.lru_list);
-	ip6_frags.nqueues++;
-	write_unlock(&ip6_frags.lock);
-	return fq;
+	q = inet_frag_intern(&fq_in->q, &ip6_frags, hash);
+	return container_of(q, struct frag_queue, q);
 }
 
 
@@ -699,5 +684,6 @@ void __init ipv6_frag_init(void)
 	ip6_frags.destructor = ip6_frag_free;
 	ip6_frags.skb_free = NULL;
 	ip6_frags.qsize = sizeof(struct frag_queue);
+	ip6_frags.equal = ip6_frag_equal;
 	inet_frags_init(&ip6_frags);
 }
-- 
1.5.3.4