ipv6: unify fragment thresh handling code

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Kubeček <mkubecek@suse.cz>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_frag.h

@@ -61,7 +61,7 @@ void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f);
 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 netns_frags *nf, struct inet_frags *f);
+int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force);
 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 		struct inet_frags *f, void *key, unsigned int hash)
 	__releases(&f->lock);

net/ipv4/inet_fragment.c

@@ -89,7 +89,7 @@ void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
 	nf->low_thresh = 0;
 
 	local_bh_disable();
-	inet_frag_evictor(nf, f);
+	inet_frag_evictor(nf, f, true);
 	local_bh_enable();
 }
 EXPORT_SYMBOL(inet_frags_exit_net);
@@ -158,11 +158,16 @@ void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
 }
 EXPORT_SYMBOL(inet_frag_destroy);
 
-int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f)
+int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force)
 {
 	struct inet_frag_queue *q;
 	int work, evicted = 0;
 
+	if (!force) {
+		if (atomic_read(&nf->mem) <= nf->high_thresh)
+			return 0;
+	}
+
 	work = atomic_read(&nf->mem) - nf->low_thresh;
 	while (work > 0) {
 		read_lock(&f->lock);

net/ipv4/ip_fragment.c

@@ -219,7 +219,7 @@ static void ip_evictor(struct net *net)
 {
 	int evicted;
 
-	evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags);
+	evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags, false);
 	if (evicted)
 		IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted);
 }
@@ -684,7 +684,6 @@ int ip_defrag(struct sk_buff *skb, u32 user)
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS);
 
 	/* Start by cleaning up the memory. */
-	if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh)
 	ip_evictor(net);
 
 	/* Lookup (or create) queue header */

net/ipv6/netfilter/nf_conntrack_reasm.c

@@ -566,11 +566,9 @@ struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb, u32 user)
 	hdr = ipv6_hdr(clone);
 	fhdr = (struct frag_hdr *)skb_transport_header(clone);
 
-	if (atomic_read(&net->nf_frag.frags.mem) > net->nf_frag.frags.high_thresh) {
 	local_bh_disable();
-		inet_frag_evictor(&net->nf_frag.frags, &nf_frags);
+	inet_frag_evictor(&net->nf_frag.frags, &nf_frags, false);
 	local_bh_enable();
-	}
 
 	fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr);
 	if (fq == NULL) {

net/ipv6/reassembly.c

@@ -131,15 +131,6 @@ void ip6_frag_init(struct inet_frag_queue *q, void *a)
 }
 EXPORT_SYMBOL(ip6_frag_init);
 
-static void ip6_evictor(struct net *net, struct inet6_dev *idev)
-{
-	int evicted;
-
-	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
-	if (evicted)
-		IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
-}
-
 void ip6_expire_frag_queue(struct net *net, struct frag_queue *fq,
 			   struct inet_frags *frags)
 {
@@ -515,6 +506,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 	struct frag_queue *fq;
 	const struct ipv6hdr *hdr = ipv6_hdr(skb);
 	struct net *net = dev_net(skb_dst(skb)->dev);
+	int evicted;
 
 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
 
@@ -539,8 +531,10 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 		return 1;
 	}
 
-	if (atomic_read(&net->ipv6.frags.mem) > net->ipv6.frags.high_thresh)
-		ip6_evictor(net, ip6_dst_idev(skb_dst(skb)));
+	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags, false);
+	if (evicted)
+		IP6_ADD_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
+				 IPSTATS_MIB_REASMFAILS, evicted);
 
 	fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr);
 	if (fq != NULL) {