From fb69be697916a2d0a9badcdef7f20fcfad1233bc Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Tue, 30 Oct 2018 22:01:24 +0100 Subject: batman-adv: Add inconsistent hardif netlink dump detection The netlink dump functionality transfers a large number of entries from the kernel to userspace. It is rather likely that the transfer has to interrupted and later continued. During that time, it can happen that either new entries are added or removed. The userspace could than either receive some entries multiple times or miss entries. Commit 670dc2833d14 ("netlink: advertise incomplete dumps") introduced a mechanism to inform userspace about this problem. Userspace can then decide whether it is necessary or not to retry dumping the information again. The netlink dump functions have to be switched to exclusive locks to avoid changes while the current message is prepared. And an external generation sequence counter is introduced which tracks all modifications of the list. Reported-by: Matthias Schiffer Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/hard-interface.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/batman-adv/hard-interface.c') diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index 781c5b6e6e8e..508f4416dfc9 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -951,6 +951,7 @@ batadv_hardif_add_interface(struct net_device *net_dev) batadv_check_known_mac_addr(hard_iface->net_dev); kref_get(&hard_iface->refcount); list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list); + batadv_hardif_generation++; return hard_iface; @@ -993,6 +994,7 @@ void batadv_hardif_remove_interfaces(void) list_for_each_entry_safe(hard_iface, hard_iface_tmp, &batadv_hardif_list, list) { list_del_rcu(&hard_iface->list); + batadv_hardif_generation++; batadv_hardif_remove_interface(hard_iface); } rtnl_unlock(); @@ -1054,6 +1056,7 @@ static int batadv_hard_if_event(struct notifier_block *this, case NETDEV_UNREGISTER: case NETDEV_PRE_TYPE_CHANGE: list_del_rcu(&hard_iface->list); + batadv_hardif_generation++; batadv_hardif_remove_interface(hard_iface); break; -- cgit v1.2.3