From: Gao Feng <f...@ikuai8.com>

When master_idx is invalid, it is zero. It is unnecessary to iterate
all netdevs. Because l3mdev_master_ifindex_rcu(dev) != master_idx must
be true.
Now put this loop into the condition block when master_idx is valid.

Signed-off-by: Gao Feng <f...@ikuai8.com>
---
 net/ipv4/devinet.c | 68 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 36 insertions(+), 32 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 5d367b7..1a9e550 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1219,42 +1219,46 @@ __be32 inet_select_addr(const struct net_device *dev, 
__be32 dst, int scope)
 no_in_dev:
        master_idx = l3mdev_master_ifindex_rcu(dev);
 
-       /* For VRFs, the VRF device takes the place of the loopback device,
-        * with addresses on it being preferred.  Note in such cases the
-        * loopback device will be among the devices that fail the master_idx
-        * equality check in the loop below.
-        */
-       if (master_idx &&
-           (dev = dev_get_by_index_rcu(net, master_idx)) &&
-           (in_dev = __in_dev_get_rcu(dev))) {
-               for_primary_ifa(in_dev) {
-                       if (ifa->ifa_scope != RT_SCOPE_LINK &&
-                           ifa->ifa_scope <= scope) {
-                               addr = ifa->ifa_local;
-                               goto out_unlock;
+       if (master_idx) {
+               /* For VRFs, the VRF device takes the place of the loopback 
device,
+                * with addresses on it being preferred.  Note in such cases the
+                * loopback device will be among the devices that fail the 
master_idx
+                * equality check in the loop below.
+                */
+               dev = dev_get_by_index_rcu(net, master_idx);
+               if (dev) {
+                       in_dev = __in_dev_get_rcu(dev);
+                       if (in_dev) {
+                               for_primary_ifa(in_dev) {
+                                       if (ifa->ifa_scope != RT_SCOPE_LINK &&
+                                           ifa->ifa_scope <= scope) {
+                                               addr = ifa->ifa_local;
+                                               goto out_unlock;
+                                       }
+                               } endfor_ifa(in_dev);
                        }
-               } endfor_ifa(in_dev);
-       }
+               }
 
-       /* Not loopback addresses on loopback should be preferred
-          in this case. It is important that lo is the first interface
-          in dev_base list.
-        */
-       for_each_netdev_rcu(net, dev) {
-               if (l3mdev_master_ifindex_rcu(dev) != master_idx)
-                       continue;
+               /* Not loopback addresses on loopback should be preferred
+                  in this case. It is important that lo is the first interface
+                  in dev_base list.
+                */
+               for_each_netdev_rcu(net, dev) {
+                       if (l3mdev_master_ifindex_rcu(dev) != master_idx)
+                               continue;
 
-               in_dev = __in_dev_get_rcu(dev);
-               if (!in_dev)
-                       continue;
+                       in_dev = __in_dev_get_rcu(dev);
+                       if (!in_dev)
+                               continue;
 
-               for_primary_ifa(in_dev) {
-                       if (ifa->ifa_scope != RT_SCOPE_LINK &&
-                           ifa->ifa_scope <= scope) {
-                               addr = ifa->ifa_local;
-                               goto out_unlock;
-                       }
-               } endfor_ifa(in_dev);
+                       for_primary_ifa(in_dev) {
+                               if (ifa->ifa_scope != RT_SCOPE_LINK &&
+                                   ifa->ifa_scope <= scope) {
+                                       addr = ifa->ifa_local;
+                                       goto out_unlock;
+                               }
+                       } endfor_ifa(in_dev);
+               }
        }
 out_unlock:
        rcu_read_unlock();
-- 
1.9.1


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