diff options
| author | Sven Eckelmann <sven@narfation.org> | 2016-01-14 15:28:19 +0100 |
|---|---|---|
| committer | Antonio Quartulli <a@unstable.cc> | 2016-01-16 22:48:29 +0800 |
| commit | 63b399272294e7a939cde41792dca38c549f0484 (patch) | |
| tree | 73ccce6e249a893dc25f9e692b3b7a1a8a98f81e | |
| parent | 6c3f5aef1159a278b54642ebc0bbb5cdab7630cf (diff) | |
| download | linux-63b399272294e7a939cde41792dca38c549f0484.tar.bz2 | |
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>
| -rw-r--r-- | net/batman-adv/bridge_loop_avoidance.c | 10 |
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 d5d71ac96c8a..c24c481b666f 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); } /** |