diff mbox

batman-adv: Fix symmetry check / route flapping in multi interface setups

Message ID 1347745906-12749-1-git-send-email-linus.luessing@web.de (mailing list archive)
State Superseded, archived
Headers

Commit Message

Linus Lüssing Sept. 15, 2012, 9:51 p.m. UTC 
  If receiving an OGM from a neighbor other than the currently selected
and if it has the same TQ then we are supposed to switch if this
neighbor provides a more symmetric link than the currently selected one.

However this symmetry check currently is broken if the interface of the
neighbor we received the OGM from and the one of the currently selected
neighbor differ: We are currently trying to determine the symmetry of the
link towards the selected router via the link we received the OGM from
instead of just checking via the link towards the currently selected
router.

This leads to way more route switches than necessary and can lead to
permanent route flapping in many common multi interface setups.

This patch fixes this issue by using the right interface for this
symmetry check.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
This fixes the route flapping observed in ticket 163 (but unfortunately
doesn't fix the main issue of this ticket, the starving routes, yet).

 bat_iv_ogm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Antonio Quartulli Sept. 16, 2012, 10:12 a.m. UTC | #1 
On Sat, Sep 15, 2012 at 11:51:46 +0200, Linus Lüssing wrote:
> If receiving an OGM from a neighbor other than the currently selected
> and if it has the same TQ then we are supposed to switch if this
> neighbor provides a more symmetric link than the currently selected one.
> 
> However this symmetry check currently is broken if the interface of the
> neighbor we received the OGM from and the one of the currently selected
> neighbor differ: We are currently trying to determine the symmetry of the
> link towards the selected router via the link we received the OGM from
> instead of just checking via the link towards the currently selected
> router.
> 
> This leads to way more route switches than necessary and can lead to
> permanent route flapping in many common multi interface setups.
> 
> This patch fixes this issue by using the right interface for this
> symmetry check.
> 
> Signed-off-by: Linus Lüssing <linus.luessing@web.de>
> ---
> This fixes the route flapping observed in ticket 163 (but unfortunately
> doesn't fix the main issue of this ticket, the starving routes, yet).
> 
>  bat_iv_ogm.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c
> index 7f0adad..2c6b560 100644
> --- a/bat_iv_ogm.c
> +++ b/bat_iv_ogm.c
> @@ -743,7 +743,8 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
>  	if (router && (neigh_node->tq_avg == router->tq_avg)) {
>  		orig_node_tmp = router->orig_node;
>  		spin_lock_bh(&orig_node_tmp->ogm_cnt_lock);
> -		sum_orig = orig_node_tmp->bcast_own_sum[if_incoming->if_num];
> +		sum_orig = orig_node_tmp->
> +				bcast_own_sum[router->if_incoming->if_num];

what about:
	int if_num;
	...
		if_num = router->if_incoming->if_num;
		sum_orig = orig_node_tmp->bcast_own_sum[if_num];

?
diff mbox

Patch

diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c
index 7f0adad..2c6b560 100644
--- a/bat_iv_ogm.c
+++ b/bat_iv_ogm.c
@@ -743,7 +743,8 @@  batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
 	if (router && (neigh_node->tq_avg == router->tq_avg)) {
 		orig_node_tmp = router->orig_node;
 		spin_lock_bh(&orig_node_tmp->ogm_cnt_lock);
-		sum_orig = orig_node_tmp->bcast_own_sum[if_incoming->if_num];
+		sum_orig = orig_node_tmp->
+				bcast_own_sum[router->if_incoming->if_num];
 		spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);
 
 		orig_node_tmp = neigh_node->orig_node;