From: Sven Eckelmann Date: Wed, 29 Jun 2016 21:45:57 +0000 (+0200) Subject: batman-adv: Fix consistency of update route messages X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b5dcbad25219b82408e15e6d775a406be2116af1;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git batman-adv: Fix consistency of update route messages The debug messages of _batadv_update_route were printed before the actual route change is done. At this point it is not really known which curr_router will be replaced. Thus the messages could print the wrong operation. Printing the debug messages after the operation was done avoids this problem. Signed-off-by: Sven Eckelmann Signed-off-by: Marek Lindner Signed-off-by: Simon Wunderlich --- diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 7602c001e92b..610f2c45edcd 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -74,11 +74,23 @@ static void _batadv_update_route(struct batadv_priv *bat_priv, if (!orig_ifinfo) return; - rcu_read_lock(); - curr_router = rcu_dereference(orig_ifinfo->router); - if (curr_router && !kref_get_unless_zero(&curr_router->refcount)) - curr_router = NULL; - rcu_read_unlock(); + spin_lock_bh(&orig_node->neigh_list_lock); + /* curr_router used earlier may not be the current orig_ifinfo->router + * anymore because it was dereferenced outside of the neigh_list_lock + * protected region. After the new best neighbor has replace the current + * best neighbor the reference counter needs to decrease. Consequently, + * the code needs to ensure the curr_router variable contains a pointer + * to the replaced best neighbor. + */ + curr_router = rcu_dereference_protected(orig_ifinfo->router, true); + + /* increase refcount of new best neighbor */ + if (neigh_node) + kref_get(&neigh_node->refcount); + + rcu_assign_pointer(orig_ifinfo->router, neigh_node); + spin_unlock_bh(&orig_node->neigh_list_lock); + batadv_orig_ifinfo_put(orig_ifinfo); /* route deleted */ if ((curr_router) && (!neigh_node)) { @@ -100,27 +112,6 @@ static void _batadv_update_route(struct batadv_priv *bat_priv, curr_router->addr); } - if (curr_router) - batadv_neigh_node_put(curr_router); - - spin_lock_bh(&orig_node->neigh_list_lock); - /* curr_router used earlier may not be the current orig_ifinfo->router - * anymore because it was dereferenced outside of the neigh_list_lock - * protected region. After the new best neighbor has replace the current - * best neighbor the reference counter needs to decrease. Consequently, - * the code needs to ensure the curr_router variable contains a pointer - * to the replaced best neighbor. - */ - curr_router = rcu_dereference_protected(orig_ifinfo->router, true); - - /* increase refcount of new best neighbor */ - if (neigh_node) - kref_get(&neigh_node->refcount); - - rcu_assign_pointer(orig_ifinfo->router, neigh_node); - spin_unlock_bh(&orig_node->neigh_list_lock); - batadv_orig_ifinfo_put(orig_ifinfo); - /* decrease refcount of previous best neighbor */ if (curr_router) batadv_neigh_node_put(curr_router);