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genetlink: introduce pre_doit/post_doit hooks

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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>
This commit is contained in:
Johannes Berg 2010-10-04 21:14:03 +02:00 committed by John W. Linville
parent 2ee4e27cf2
commit ff4c92d85c
2 changed files with 31 additions and 1 deletions
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18
include/net/genetlink.h
View file

@ -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,

14
net/netlink/genetlink.c
View file

@ -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)