ipv6: no more dev_put() in datagram_send_ctl()

Avoids touching device refcount in datagram_send_ctl(), thanks to RCU

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

1 files changed, 9 insertions, 5 deletions

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 9f70452a69e7..e6f9cdf780fe 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -537,12 +537,17 @@ int datagram_send_ctl(struct net *net,
 
                         addr_type = __ipv6_addr_type(&src_info->ipi6_addr);
 
+                        rcu_read_lock();
                         if (fl->oif) {
-                                dev = dev_get_by_index(net, fl->oif);
-                                if (!dev)
+                                dev = dev_get_by_index_rcu(net, fl->oif);
+                                if (!dev) {
+                                        rcu_read_unlock();
                                         return -ENODEV;
-                        } else if (addr_type & IPV6_ADDR_LINKLOCAL)
+                                }
+                        } else if (addr_type & IPV6_ADDR_LINKLOCAL) {
+                                rcu_read_unlock();
                                 return -EINVAL;
+                        }
 
                         if (addr_type != IPV6_ADDR_ANY) {
                                 int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
@@ -553,8 +558,7 @@ int datagram_send_ctl(struct net *net,
                                         ipv6_addr_copy(&fl->fl6_src, &src_info->ipi6_addr);
                         }
 
-                        if (dev)
-                                dev_put(dev);
+                        rcu_read_unlock();
 
                         if (err)
                                 goto exit_f;