net: use the frag lru_lock to protect netns_frags.nqueues update

Move the protection of netns_frags.nqueues updates under the LRU_lock,
instead of the write lock.  As they are located on the same cacheline,
and this is also needed when transitioning to use per hash bucket locking.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/inet_frag.h

@@ -143,6 +143,7 @@ static inline void inet_frag_lru_del(struct inet_frag_queue *q)
 {
 	spin_lock(&q->net->lru_lock);
 	list_del(&q->lru_list);
+	q->net->nqueues--;
 	spin_unlock(&q->net->lru_lock);
 }
 
@@ -151,6 +152,7 @@ static inline void inet_frag_lru_add(struct netns_frags *nf,
 {
 	spin_lock(&nf->lru_lock);
 	list_add_tail(&q->lru_list, &nf->lru_list);
+	q->net->nqueues++;
 	spin_unlock(&nf->lru_lock);
 }
 

net/ipv4/inet_fragment.c

@@ -124,7 +124,6 @@ static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
 {
 	write_lock(&f->lock);
 	hlist_del(&fq->list);
-	fq->net->nqueues--;
 	write_unlock(&f->lock);
 	inet_frag_lru_del(fq);
 }
@@ -260,7 +259,6 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
 
 	atomic_inc(&qp->refcnt);
 	hlist_add_head(&qp->list, &f->hash[hash]);
-	nf->nqueues++;
 	write_unlock(&f->lock);
 	inet_frag_lru_add(nf, qp);
 	return qp;