ip_frag: dont touch device refcount

When sending fragmentation expiration ICMP V4/V6 messages,
we can avoid touching device refcount, thanks to RCU

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 7 deletions

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index da5bd0ed83df..dce699fb2672 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -208,18 +208,17 @@ static void ip6_frag_expire(unsigned long data)
         fq_kill(fq);
 
         net = container_of(fq->q.net, struct net, ipv6.frags);
-        dev = dev_get_by_index(net, fq->iif);
+        rcu_read_lock();
+        dev = dev_get_by_index_rcu(net, fq->iif);
         if (!dev)
-                goto out;
+                goto out_rcu_unlock;
 
-        rcu_read_lock();
         IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
         IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
-        rcu_read_unlock();
 
         /* Don't send error if the first segment did not arrive. */
         if (!(fq->q.last_in & INET_FRAG_FIRST_IN) || !fq->q.fragments)
-                goto out;
+                goto out_rcu_unlock;
 
         /*
            But use as source device on which LAST ARRIVED
@@ -228,9 +227,9 @@ static void ip6_frag_expire(unsigned long data)
          */
         fq->q.fragments->dev = dev;
         icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
+out_rcu_unlock:
+        rcu_read_unlock();
 out:
-        if (dev)
-                dev_put(dev);
         spin_unlock(&fq->q.lock);
         fq_put(fq);
 }