From 670dc2833d144375eac36ad74111495a825a9288 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 20 Jun 2011 13:40:46 +0200 Subject: netlink: advertise incomplete dumps Consider the following situation: * a dump that would show 8 entries, four in the first round, and four in the second * between the first and second rounds, 6 entries are removed * now the second round will not show any entry, and even if there is a sequence/generation counter the application will not know To solve this problem, add a new flag NLM_F_DUMP_INTR to the netlink header that indicates the dump wasn't consistent, this flag can also be set on the MSG_DONE message that terminates the dump, and as such above situation can be detected. To achieve this, add a sequence counter to the netlink callback struct. Of course, netlink code still needs to use this new functionality. The correct way to do that is to always set cb->seq when a dumpit callback is invoked and call nl_dump_check_consistent() for each new message. The core code will also call this function for the final MSG_DONE message. To make it usable with generic netlink, a new function genlmsg_nlhdr() is needed to obtain the netlink header from the genetlink user header. Signed-off-by: Johannes Berg Acked-by: David S. Miller Signed-off-by: John W. Linville --- net/netlink/af_netlink.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'net/netlink') diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 6ef64adf736..a7ec8512f55 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1693,6 +1693,8 @@ static int netlink_dump(struct sock *sk) if (!nlh) goto errout_skb; + nl_dump_check_consistent(cb, nlh); + memcpy(nlmsg_data(nlh), &len, sizeof(len)); if (sk_filter(sk, skb)) -- cgit v1.2.3