Re: [PATCH net-next] net: core: Traverse the adjacency list from first entry

David Ahern
2016-10-26T15:05:38Z

On 10/26/16 12:39 AM, idosch@idosch.org wrote:
> From: Ido Schimmel <idosch@mellanox.com>
>
> netdev_next_lower_dev() returns NULL when we finished traversing the
> adjacency list ('iter' points to the list's head). Therefore, we must
> start traversing the list from the first entry and not its head.
>
> Fixes: 1a3f060c1a47 ("net: Introduce new api for walking upper and lower devices")
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> ---
> net/core/dev.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index f55fb45..d9c937f 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5419,7 +5419,7 @@ int netdev_walk_all_lower_dev(struct net_device *dev,
> struct list_head *iter;
> int ret;
>
> - for (iter = &dev->adj_list.lower,
> + for (iter = dev->adj_list.lower.next,
> ldev = netdev_next_lower_dev(dev, &iter);
> ldev;
> ldev = netdev_next_lower_dev(dev, &iter)) {
>

How about this instead? It keeps the 3 walk functions in sync modulo the rcu reference:

diff --git a/net/core/dev.c b/net/core/dev.c
index f55fb4536016..6aa43cd8cbb5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5400,12 +5400,12 @@ static struct net_device *netdev_next_lower_dev(struct net_device *dev,
{
struct netdev_adjacent *lower;

- lower = list_entry(*iter, struct netdev_adjacent, list);
+ lower = list_entry((*iter)->next, struct netdev_adjacent, list);

if (&lower->list == &dev->adj_list.lower)
return NULL;

- *iter = lower->list.next;
+ *iter = &lower->list;

return lower->dev;
}