Wed, Oct 12, 2016 at 10:51:50PM CEST, wrote:
>This patch introduces netdev_walk_all_upper_dev_rcu,
>netdev_walk_all_lower_dev and netdev_walk_all_lower_dev_rcu. These
>functions recursively walk the adj_list of devices to determine all upper
>and lower devices.
>The functions take a callback function that is invoked for each device
>in the list. If the callback returns non-0, the walk is terminated and
>the functions return that code back to callers.
>Signed-off-by: David Ahern <>


>+int netdev_walk_all_lower_dev(struct net_device *dev,
>+                            int (*fn)(struct net_device *dev,
>+                                      void *data),
>+                            void *data)
>+      struct list_head *iter;
>+      struct net_device *ldev;
>+      int ret;
>+      for (iter = &(dev)->adj_list.lower,
>+           ldev = netdev_next_lower_dev(dev, &(iter));
>+           ldev;
>+           ldev = netdev_next_lower_dev(dev, &(iter))) {
>+              /* first is the lower device itself */
>+              ret = fn(ldev, data);
>+              if (ret)
>+                      return ret;
>+              /* then look at all of its lower devices */
>+              ret = netdev_walk_all_lower_dev(ldev, fn, data);

I believe that Veaceslav's reason to collapse the upper/lower trees was
to avoid this recursivity. I also believe that the recursivity was a big
issue for DaveM and BenH. Something changed?

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