Commit ff4c92d8 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

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: default avatarJohannes Berg <johannes.berg@intel.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 2ee4e27c

include/net/genetlink.h

+18 −0
Original line number Diff line number Diff line
@@ -20,6 +20,9 @@ struct genl_multicast_group { 
	u32			id;

};



struct genl_ops;

struct genl_info;



/**

 * struct genl_family - generic netlink family

 * @id: protocol family idenfitier
@@ -29,6 +32,10 @@ struct genl_multicast_group { 
 * @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 @@ struct genl_family { 
	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 @@ struct genl_family { 
 * @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 @@ struct genl_info { 
#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 @@ static inline void genl_info_net_set(struct genl_info *info, struct net *net) 
/**

 * 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 @@ static inline void genl_info_net_set(struct genl_info *info, struct net *net) 
 */

struct genl_ops {

	u8			cmd;

	u8			internal_flags;

	unsigned int		flags;

	const struct nla_policy	*policy;

	int		       (*doit)(struct sk_buff *skb,

net/netlink/genetlink.c

+13 −1
Original line number Diff line number Diff line
@@ -547,8 +547,20 @@ static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 
	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)

CRA Git | Maintained and supported by SUSTech CRA and CCSE