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/include/net/genetlink.h b/include/net/genetlink.h
index f7dcd2c..8a64b81 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -20,6 +20,9 @@
u32 id;
};
+struct genl_ops;
+struct genl_info;
+
/**
* struct genl_family - generic netlink family
* @id: protocol family idenfitier
@@ -29,6 +32,10 @@
* @maxattr: maximum number of attributes supported
* @netnsok: set to true if the family can handle network
* namespaces and should be presented in all of them
+ * @pre_doit: called before an operation's doit callback, it may
+ * do additional, common, filtering and return an error
+ * @post_doit: called after an operation's doit callback, it may
+ * undo operations done by pre_doit, for example release locks
* @attrbuf: buffer to store parsed attributes
* @ops_list: list of all assigned operations
* @family_list: family list
@@ -41,6 +48,12 @@
unsigned int version;
unsigned int maxattr;
bool netnsok;
+ int (*pre_doit)(struct genl_ops *ops,
+ struct sk_buff *skb,
+ struct genl_info *info);
+ void (*post_doit)(struct genl_ops *ops,
+ struct sk_buff *skb,
+ struct genl_info *info);
struct nlattr ** attrbuf; /* private */
struct list_head ops_list; /* private */
struct list_head family_list; /* private */
@@ -55,6 +68,8 @@
* @genlhdr: generic netlink message header
* @userhdr: user specific header
* @attrs: netlink attributes
+ * @_net: network namespace
+ * @user_ptr: user pointers
*/
struct genl_info {
u32 snd_seq;
@@ -66,6 +81,7 @@
#ifdef CONFIG_NET_NS
struct net * _net;
#endif
+ void * user_ptr[2];
};
static inline struct net *genl_info_net(struct genl_info *info)
@@ -81,6 +97,7 @@
/**
* struct genl_ops - generic netlink operations
* @cmd: command identifier
+ * @internal_flags: flags used by the family
* @flags: flags
* @policy: attribute validation policy
* @doit: standard command callback
@@ -90,6 +107,7 @@
*/
struct genl_ops {
u8 cmd;
+ u8 internal_flags;
unsigned int flags;
const struct nla_policy *policy;
int (*doit)(struct sk_buff *skb,
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)
