net: frag, move LRU list maintenance outside of rwlock

Updating the fragmentation queues LRU (Least-Recently-Used) list,
required taking the hash writer lock.  However, the LRU list isn't
tied to the hash at all, so we can use a separate lock for it.

Original-idea-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 11 insertions, 14 deletions

diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index b82520565098..2e453bde6992 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -75,6 +75,7 @@ void inet_frags_init_net(struct netns_frags *nf)
         nf->nqueues = 0;
         init_frag_mem_limit(nf);
         INIT_LIST_HEAD(&nf->lru_list);
+        spin_lock_init(&nf->lru_lock);
 }
 EXPORT_SYMBOL(inet_frags_init_net);
 
@@ -100,9 +101,9 @@ static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
 {
         write_lock(&f->lock);
         hlist_del(&fq->list);
-        list_del(&fq->lru_list);
         fq->net->nqueues--;
         write_unlock(&f->lock);
+        inet_frag_lru_del(fq);
 }
 
 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
@@ -170,16 +171,17 @@ int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force)
 
         work = frag_mem_limit(nf) - nf->low_thresh;
         while (work > 0) {
-                read_lock(&f->lock);
+                spin_lock(&nf->lru_lock);
+
                 if (list_empty(&nf->lru_list)) {
-                        read_unlock(&f->lock);
+                        spin_unlock(&nf->lru_lock);
                         break;
                 }
 
                 q = list_first_entry(&nf->lru_list,
                                 struct inet_frag_queue, lru_list);
                 atomic_inc(&q->refcnt);
-                read_unlock(&f->lock);
+                spin_unlock(&nf->lru_lock);
 
                 spin_lock(&q->lock);
                 if (!(q->last_in & INET_FRAG_COMPLETE))
@@ -233,9 +235,9 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
 
         atomic_inc(&qp->refcnt);
         hlist_add_head(&qp->list, &f->hash[hash]);
-        list_add_tail(&qp->lru_list, &nf->lru_list);
         nf->nqueues++;
         write_unlock(&f->lock);
+        inet_frag_lru_add(nf, qp);
         return qp;
 }
 
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 927fe58caf46..1211613c6c34 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -529,9 +529,7 @@ found:
             qp->q.meat == qp->q.len)
                 return ip_frag_reasm(qp, prev, dev);
 
-        write_lock(&ip4_frags.lock);
-        list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list);
-        write_unlock(&ip4_frags.lock);
+        inet_frag_lru_move(&qp->q);
         return -EINPROGRESS;
 
 err:
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 07ef2949c946..c674f158efa8 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -328,9 +328,8 @@ found:
                 fq->nhoffset = nhoff;
                 fq->q.last_in |= INET_FRAG_FIRST_IN;
         }
-        write_lock(&nf_frags.lock);
-        list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
-        write_unlock(&nf_frags.lock);
+
+        inet_frag_lru_move(&fq->q);
         return 0;
 
 discard_fq:
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 18cb8defcdb2..bab2c270f292 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -341,9 +341,7 @@ found:
             fq->q.meat == fq->q.len)
                 return ip6_frag_reasm(fq, prev, dev);
 
-        write_lock(&ip6_frags.lock);
-        list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
-        write_unlock(&ip6_frags.lock);
+        inet_frag_lru_move(&fq->q);
         return -1;
 
 discard_fq: