Re: [PATCH net-next 02/11] net: Introduce new api for walking upper and lower devices

Jiri Pirko
2016-10-13T07:30:29Z

Wed, Oct 12, 2016 at 10:51:50PM CEST, dsa@cumulusnetworks.com 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 <dsa@cumulusnetworks.com>

[...]

>+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?