[linux-next] LinuxNextTracking branch, master, updated. next-20150107

batman at open-mesh.org batman at open-mesh.org
Thu Jan 8 00:21:29 CET 2015


The following commit has been merged in the master branch:
commit 2c667a339c7a6f23e1b7e23eed06f2564cff0c91
Author: Linus Lüssing <linus.luessing at 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 at c0d3.blue>
    Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Antonio Quartulli <antonio at meshcoding.com>

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 6a48451..648bdba 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/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

-- 
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