net: add adj_list to save only neighbours

Currently, we distinguish neighbours (first-level linked devices) from
non-neighbours by the neighbour bool in the netdev_adjacent. This could be
quite time-consuming in case we would like to traverse *only* through
neighbours - cause we'd have to traverse through all devices and check for
this flag, and in a (quite common) scenario where we have lots of vlans on
top of bridge, which is on top of a bond - the bonding would have to go
through all those vlans to get its upper neighbour linked devices.

This situation is really unpleasant, cause there are already a lot of cases
when a device with slaves needs to go through them in hot path.

To fix this, introduce a new upper/lower device lists structure -
adj_list, which contains only the neighbours. It works always in
pair with the all_adj_list structure (renamed from upper/lower_dev_list),
i.e. both of them contain the same links, only that all_adj_list contains
also non-neighbour device links. It's really a small change visible,
currently, only for __netdev_adjacent_dev_insert/remove(), and doesn't
change the main linked logic at all.

Also, add some comments a fix a name collision in
netdev_for_each_upper_dev_rcu() and rework the naming by the following
rules:

netdev_(all_)(upper|lower)_*

If "all_" is present, then we work with the whole list of upper/lower
devices, otherwise - only with direct neighbours. Uninline functions - to
get better stack traces.

CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Jiri Pirko <jiri@resnulli.us>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 9 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 3de49ac..514045c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1143,8 +1143,18 @@ struct net_device {
 	struct list_head	dev_list;
 	struct list_head	napi_list;
 	struct list_head	unreg_list;
-	struct list_head	upper_dev_list; /* List of upper devices */
-	struct list_head	lower_dev_list;
+
+	/* directly linked devices, like slaves for bonding */
+	struct {
+		struct list_head upper;
+		struct list_head lower;
+	} adj_list;
+
+	/* all linked devices, *including* neighbours */
+	struct {
+		struct list_head upper;
+		struct list_head lower;
+	} all_adj_list;
 
 
 	/* currently active device features */
@@ -2813,15 +2823,15 @@ extern int		bpf_jit_enable;
 extern bool netdev_has_upper_dev(struct net_device *dev,
 				 struct net_device *upper_dev);
 extern bool netdev_has_any_upper_dev(struct net_device *dev);
-extern struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
-							struct list_head **iter);
+extern struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
+							    struct list_head **iter);
 
 /* iterate through upper list, must be called under RCU read lock */
-#define netdev_for_each_upper_dev_rcu(dev, upper, iter) \
-	for (iter = &(dev)->upper_dev_list, \
-	     upper = netdev_upper_get_next_dev_rcu(dev, &(iter)); \
-	     upper; \
-	     upper = netdev_upper_get_next_dev_rcu(dev, &(iter)))
+#define netdev_for_each_all_upper_dev_rcu(dev, updev, iter) \
+	for (iter = &(dev)->all_adj_list.upper, \
+	     updev = netdev_all_upper_get_next_dev_rcu(dev, &(iter)); \
+	     updev; \
+	     updev = netdev_all_upper_get_next_dev_rcu(dev, &(iter)))
 
 extern struct net_device *netdev_master_upper_dev_get(struct net_device *dev);
 extern struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev);