[B.A.T.M.A.N.] [PATCH] batman-adv: Fix symmetry check / route flapping in multi interface setups

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Linus Lüssing

15 Sep 2012 15 Sep '12

9:51 p.m.

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]; spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

orig_node_tmp = neigh_node->orig_node;

-- 1.7.10.4

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Antonio Quartulli

16 Sep 16 Sep

10:12 a.m.

New subject: [B.A.T.M.A.N.] [PATCH] batman-adv: Fix symmetry check / route flapping in multi interface setups

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];

-- Antonio Quartulli ..each of us alone is worth nothing.. Ernesto "Che" Guevara

Linus Lüssing

18 Sep 18 Sep

1:01 a.m.

New subject: [B.A.T.M.A.N.] [PATCHv2] batman-adv: Fix symmetry check / route flapping in multi interface setups

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 --- bat_iv_ogm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c index 7f0adad..a92a663 100644 --- a/bat_iv_ogm.c +++ b/bat_iv_ogm.c @@ -657,6 +657,7 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv, struct batadv_neigh_node *router = NULL; struct batadv_orig_node *orig_node_tmp; struct hlist_node *node; + int if_num; uint8_t sum_orig, sum_neigh; uint8_t *neigh_addr; uint8_t tq_avg; @@ -743,7 +744,8 @@ 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]; + if_num = router->if_incoming->if_num; + sum_orig = orig_node_tmp->bcast_own_sum[if_num]; spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

orig_node_tmp = neigh_node->orig_node;

-- 1.7.10.4

Marek Lindner

23 Sep 23 Sep

9:15 a.m.

New subject: [B.A.T.M.A.N.] [PATCHv2] batman-adv: Fix symmetry check / route flapping in multi interface setups

On Tuesday, September 18, 2012 09:01:08 Linus Lüssing wrote:

...

@@ -743,7 +744,8 @@ 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]; + if_num = router->if_incoming->if_num;
          sum_orig = orig_node_tmp->bcast_own_sum[if_num];
          spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

          orig_node_tmp = neigh_node->orig_node;

Good catch! May I suggest another modifcation to make this section easier to understand ? It won't change any behavior it just makes it easier to see where if_num is coming from.

Cheers, Marek

Marek Lindner

9:16 a.m.

New subject: [B.A.T.M.A.N.] [PATCHv3] batman-adv: Fix symmetry check / route flapping in multi interface setups

From: Linus Lüssing linus.luessing@web.de

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 --- bat_iv_ogm.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c index 7f0adad..75403a4 100644 --- a/bat_iv_ogm.c +++ b/bat_iv_ogm.c @@ -657,6 +657,7 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv, struct batadv_neigh_node *router = NULL; struct batadv_orig_node *orig_node_tmp; struct hlist_node *node; + int if_num; uint8_t sum_orig, sum_neigh; uint8_t *neigh_addr; uint8_t tq_avg; @@ -743,12 +744,14 @@ 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]; + if_num = router->if_incoming->if_num; + sum_orig = orig_node_tmp->bcast_own_sum[if_num]; spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

orig_node_tmp = neigh_node->orig_node; spin_lock_bh(&orig_node_tmp->ogm_cnt_lock); - sum_neigh = orig_node_tmp->bcast_own_sum[if_incoming->if_num]; + if_num = neigh_node->if_incoming->if_num; + sum_neigh = orig_node_tmp->bcast_own_sum[if_num]; spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

if (sum_orig >= sum_neigh)

-- 1.7.9.1

"Linus Lüssing"

10:44 a.m.

New subject: [B.A.T.M.A.N.] [PATCHv3] batman-adv: Fix symmetry check / route flapping in multi interface setups

Yes, looks good. Makes the symmetry patch look more, ehm, "symmetric".

...

Gesendet: Sonntag, 23. September 2012 um 11:16 Uhr Von: "Marek Lindner" lindner_marek@yahoo.de An: b.a.t.m.a.n@lists.open-mesh.org Cc: "Linus Lüssing" linus.luessing@web.de Betreff: [PATCHv3] batman-adv: Fix symmetry check / route flapping in multi interface setups

From: Linus Lüssing linus.luessing@web.de

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

bat_iv_ogm.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/bat_iv_ogm.c b/bat_iv_ogm.c index 7f0adad..75403a4 100644 --- a/bat_iv_ogm.c +++ b/bat_iv_ogm.c @@ -657,6 +657,7 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv, struct batadv_neigh_node *router = NULL; struct batadv_orig_node *orig_node_tmp; struct hlist_node *node;

int if_num; uint8_t sum_orig, sum_neigh; uint8_t *neigh_addr; uint8_t tq_avg;

@@ -743,12 +744,14 @@ 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];
if_num = router->if_incoming->if_num;
sum_orig = orig_node_tmp->bcast_own_sum[if_num];
spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

orig_node_tmp = neigh_node->orig_node; spin_lock_bh(&orig_node_tmp->ogm_cnt_lock);
sum_neigh = orig_node_tmp->bcast_own_sum[if_incoming->if_num];
if_num = neigh_node->if_incoming->if_num;
sum_neigh = orig_node_tmp->bcast_own_sum[if_num];
spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

if (sum_orig >= sum_neigh)
-- 1.7.9.1

Marek Lindner

3:18 p.m.

New subject: [B.A.T.M.A.N.] [PATCHv3] batman-adv: Fix symmetry check / route flapping in multi interface setups

On Sunday, September 23, 2012 18:44:54 Linus Lüssing wrote:

...

Yes, looks good. Makes the symmetry patch look more, ehm, "symmetric".

Ok, merged the patch in revision 6c9d9ee.

Thanks, Marek

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"Linus Lüssing"
Antonio Quartulli
Linus Lüssing
Marek Lindner