2019-09-28, 16:48:32 +0000, Taehee Yoo wrote:
> @@ -6790,23 +6878,45 @@ int netdev_walk_all_lower_dev(struct net_device *dev,
> void *data),
> void *data)
> {
> - struct net_device *ldev;
> - struct list_head *iter;
> - int ret;
> + struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
> + struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
> + int ret, cur = 0;
>
> - 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;
> + now = dev;
> + iter = &dev->adj_list.lower;
>
> - /* then look at all of its lower devices */
> - ret = netdev_walk_all_lower_dev(ldev, fn, data);
> - if (ret)
> - return ret;
> + while (1) {
> + if (now != dev) {
> + ret = fn(now, data);
> + if (ret)
> + return ret;
> + }
> +
> + next = NULL;
> + while (1) {
> + ldev = netdev_next_lower_dev(now, &iter);
> + if (!ldev)
> + break;
> +
> + if (!next) {
> + next = ldev;
> + niter = &ldev->adj_list.lower;
> + } else {
> + dev_stack[cur] = ldev;
> + iter_stack[cur++] = &ldev->adj_list.lower;
> + break;
> + }
> + }
> +
> + if (!next) {
> + if (!cur)
> + return 0;
Hmm, I don't think this condition is correct.
If we have this topology:
bridge0
/ | \
/ | \
/ | \
dummy0 vlan1 vlan2
| \
dummy1 dummy2
We end up with the expected lower/upper levels for all devices:
| device | upper | lower |
|---------+-------+-------|
| dummy0 | 2 | 1 |
| dummy1 | 3 | 1 |
| dummy2 | 3 | 1 |
| vlan1 | 2 | 2 |
| vlan2 | 2 | 2 |
| bridge0 | 1 | 3 |
If we then add macvlan0 on top of bridge0:
macvlan0
|
|
bridge0
/ | \
/ | \
/ | \
dummy0 vlan1 vlan2
| \
dummy1 dummy2
we can observe that __netdev_update_upper_level is only called for
some of the devices under bridge0. I added a perf probe:
# perf probe -a '__netdev_update_upper_level dev->name:string'
which gets hit for bridge0 (called directly by
__netdev_upper_dev_link) and then dummy0, vlan1, dummy1. It is never
called for vlan2 and dummy2.
After this, we have the following levels (*):
| device | upper | lower |
|----------+-------+-------|
| dummy0 | 3 | 1 |
| dummy1 | 4 | 1 |
| dummy2 | 3 | 1 |
| vlan1 | 3 | 2 |
| vlan2 | 2 | 2 |
| bridge0 | 2 | 3 |
| macvlan0 | 1 | 4 |
For dummy0, dummy1, vlan1, the upper level has increased by 1, as
expected. For dummy2 and vlan2, it's still the same, which is wrong.
(*) observed easily by adding another probe:
# perf probe -a 'dev_get_stats dev->name:string dev->upper_level
dev->lower_level'
and running "ip link"
Or you can just add prints and recompile, of course :)
> + next = dev_stack[--cur];
> + niter = iter_stack[cur];
> + }
> +
> + now = next;
> + iter = niter;
> }
>
> return 0;
--
Sabrina
