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authorSven Eckelmann <sven@narfation.org>2016-01-14 15:28:19 +0100
committerAntonio Quartulli <a@unstable.cc>2016-01-16 22:48:29 +0800
commit63b399272294e7a939cde41792dca38c549f0484 (patch)
tree73ccce6e249a893dc25f9e692b3b7a1a8a98f81e /net
parent6c3f5aef1159a278b54642ebc0bbb5cdab7630cf (diff)
downloadop-kernel-dev-63b399272294e7a939cde41792dca38c549f0484.zip
op-kernel-dev-63b399272294e7a939cde41792dca38c549f0484.tar.gz
batman-adv: Avoid recursive call_rcu for batadv_bla_claim
The batadv_claim_free_ref function uses call_rcu to delay the free of the batadv_bla_claim object until no (already started) rcu_read_lock is enabled anymore. This makes sure that no context is still trying to access the object which should be removed. But batadv_bla_claim also contains a reference to backbone_gw which must be removed. The reference drop of backbone_gw was done in the call_rcu function batadv_claim_free_rcu but should actually be done in the batadv_claim_release function to avoid nested call_rcus. This is important because rcu_barrier (e.g. batadv_softif_free or batadv_exit) will not detect the inner call_rcu as relevant for its execution. Otherwise this barrier will most likely be inserted in the queue before the callback of the first call_rcu was executed. The caller of rcu_barrier will therefore continue to run before the inner call_rcu callback finished. Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann <sven@narfation.org> Acked-by: Simon Wunderlich <sw@simonwunderlich.de> Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch> Signed-off-by: Antonio Quartulli <a@unstable.cc>
Diffstat (limited to 'net')
-rw-r--r--net/batman-adv/bridge_loop_avoidance.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index d5d71ac..c24c481 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -127,21 +127,17 @@ batadv_backbone_gw_free_ref(struct batadv_bla_backbone_gw *backbone_gw)
}
/* finally deinitialize the claim */
-static void batadv_claim_free_rcu(struct rcu_head *rcu)
+static void batadv_claim_release(struct batadv_bla_claim *claim)
{
- struct batadv_bla_claim *claim;
-
- claim = container_of(rcu, struct batadv_bla_claim, rcu);
-
batadv_backbone_gw_free_ref(claim->backbone_gw);
- kfree(claim);
+ kfree_rcu(claim, rcu);
}
/* free a claim, call claim_free_rcu if its the last reference */
static void batadv_claim_free_ref(struct batadv_bla_claim *claim)
{
if (atomic_dec_and_test(&claim->refcount))
- call_rcu(&claim->rcu, batadv_claim_free_rcu);
+ batadv_claim_release(claim);
}
/**
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