On Mon, 16 Sep 2019 22:48:00 +0900, Taehee Yoo wrote:

In order to link an adjacent node, netdev_upper_dev_link() is used
and in order to unlink an adjacent node, netdev_upper_dev_unlink() is used.
unlink operation does not fail, but link operation can fail.

In order to exchange adjacent nodes, we should unlink an old adjacent
node first. then, link a new adjacent node.
If link operation is failed, we should link an old adjacent node again.
But this link operation can fail too.
It eventually breaks the adjacent link relationship.

This patch adds an ignore flag into the netdev_adjacent structure.
If this flag is set, netdev_upper_dev_link() ignores an old adjacent
node for a moment.
So we can skip unlink operation before link operation.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>

I think there's a number of local functions here which are missing the
static keyword, we'll get a flurry of fixes as soon as we apply this.

Could you please take a look at fixing that, I think W=1 should help,
-Wmissing-prototypes in particular, if I'm remembering right.