genetlink: introduce pre_doit/post_doit hooks
Each family may have some amount of boilerplate
locking code that applies to most, or even all,
commands.
This allows a family to handle such things in
a more generic way, by allowing it to
a) include private flags in each operation
b) specify a pre_doit hook that is called,
before an operation's doit() callback and
may return an error directly,
c) specify a post_doit hook that can undo
locking or similar things done by pre_doit,
and finally
d) include two private pointers in each info
struct passed between all these operations
including doit(). (It's two because I'll
need two in nl80211 -- can be extended.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 26ed3e8..1781d99 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -547,8 +547,20 @@
info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
info.attrs = family->attrbuf;
genl_info_net_set(&info, net);
+ memset(&info.user_ptr, 0, sizeof(info.user_ptr));
- return ops->doit(skb, &info);
+ if (family->pre_doit) {
+ err = family->pre_doit(ops, skb, &info);
+ if (err)
+ return err;
+ }
+
+ err = ops->doit(skb, &info);
+
+ if (family->post_doit)
+ family->post_doit(ops, skb, &info);
+
+ return err;
}
static void genl_rcv(struct sk_buff *skb)