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>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index e0eec7450f15..3f237db0a426 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -6,6 +6,7 @@
 struct netns_frags {
         int                     nqueues;
         struct list_head        lru_list;
+        spinlock_t              lru_lock;
 
         /* The percpu_counter "mem" need to be cacheline aligned.
          *  mem.count must not share cacheline with other writers
@@ -116,4 +117,25 @@ static inline int sum_frag_mem_limit(struct netns_frags *nf)
         return percpu_counter_sum_positive(&nf->mem);
 }
 
+static inline void inet_frag_lru_move(struct inet_frag_queue *q)
+{
+        spin_lock(&q->net->lru_lock);
+        list_move_tail(&q->lru_list, &q->net->lru_list);
+        spin_unlock(&q->net->lru_lock);
+}
+
+static inline void inet_frag_lru_del(struct inet_frag_queue *q)
+{
+        spin_lock(&q->net->lru_lock);
+        list_del(&q->lru_list);
+        spin_unlock(&q->net->lru_lock);
+}
+
+static inline void inet_frag_lru_add(struct netns_frags *nf,
+                                     struct inet_frag_queue *q)
+{
+        spin_lock(&nf->lru_lock);
+        list_add_tail(&q->lru_list, &nf->lru_list);
+        spin_unlock(&nf->lru_lock);
+}
 #endif