[batman-adv] maint: batman-adv: fix delayed foreign originator recognition (8a2ad52) - commits - lists.open-mesh.org

9 Nov 2014

Repository : ssh://git@open-mesh.org/batman-adv
On branch  : maint
...

commit 8a2ad520467402d4fa9f2e5ba105597a9fc37347
Author: Linus Lüssing linus.luessing@c0d3.blue
Date:   Thu Oct 30 06:23:40 2014 +0100
batman-adv: fix delayed foreign originator recognition
Currently it can happen that the reception of an OGM from a new
    originator is not being accepted. More precisely it can happen that
    an originator struct gets allocated and initialized
    (batadv_orig_node_new()), even the TQ gets calculated and set correctly
    (batadv_iv_ogm_calc_tq()) but still the periodic orig_node purging
    thread will decide to delete it if it has a chance to jump between
    these two function calls.
This is because batadv_orig_node_new() initializes the last_seen value
    to zero and its caller (batadv_iv_ogm_orig_get()) makes it visible to
    other threads by adding it to the hash table already.
    batadv_iv_ogm_calc_tq() will set the last_seen variable to the correct,
    current time a few lines later but if the purging thread jumps in between
    that it will think that the orig_node timed out and will wrongly
    schedule it for deletion already.
If the purging interval is the same as the originator interval (which is
    the default: 1 second), then this game can continue for several rounds
    until the random OGM jitter added enough difference between these
    two (in tests, two to about four rounds seemed common).
Fixing this by initializing the last_seen variable of an orig_node
    to the current time before adding it to the hash table.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue
    Signed-off-by: Marek Lindner mareklindner@neomailbox.ch
...

8a2ad520467402d4fa9f2e5ba105597a9fc37347
 originator.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/originator.c b/originator.c
index 6a48451..648bdba 100644
--- a/originator.c
+++ b/originator.c
@@ -678,6 +678,7 @@ struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
    atomic_set(&orig_node->last_ttvn, 0);
    orig_node->tt_buff = NULL;
    orig_node->tt_buff_len = 0;
+	orig_node->last_seen = jiffies;
    reset_time = jiffies - 1 - msecs_to_jiffies(BATADV_RESET_PROTECTION_MS);
    orig_node->bcast_seqno_reset = reset_time;
 #ifdef CONFIG_BATMAN_ADV_MCAST

    