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netlink: add a start callback for starting a netlink dump 

The start callback allows the caller to set up a context for the
dump callbacks. Presumably, the context can then be destroyed in
the done callback.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2015-12-15 15:41:37 -08:00 committed by David S. Miller
parent 3502cad73c
commit fc9e50f5a5
4 changed files with 24 additions and 0 deletions
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2
include/linux/netlink.h
View File

@ -131,6 +131,7 @@ netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
struct netlink_callback {
struct sk_buff *skb;
const struct nlmsghdr *nlh;
int (*start)(struct netlink_callback *);
int (*dump)(struct sk_buff * skb,
struct netlink_callback *cb);
int (*done)(struct netlink_callback *cb);
@ -153,6 +154,7 @@ struct nlmsghdr *
__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
struct netlink_dump_control {
int (*start)(struct netlink_callback *);
int (*dump)(struct sk_buff *skb, struct netlink_callback *);
int (*done)(struct netlink_callback *);
void *data;

2
include/net/genetlink.h
View File

@ -114,6 +114,7 @@ static inline void genl_info_net_set(struct genl_info *info, struct net *net)
* @flags: flags
* @policy: attribute validation policy
* @doit: standard command callback
* @start: start callback for dumps
* @dumpit: callback for dumpers
* @done: completion callback for dumps
* @ops_list: operations list
@ -122,6 +123,7 @@ struct genl_ops {
const struct nla_policy *policy;
int (*doit)(struct sk_buff *skb,
struct genl_info *info);
int (*start)(struct netlink_callback *cb);
int (*dumpit)(struct sk_buff *skb,
struct netlink_callback *cb);
int (*done)(struct netlink_callback *cb);

4
net/netlink/af_netlink.c
View File

@ -2915,6 +2915,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
cb = &nlk->cb;
memset(cb, 0, sizeof(*cb));
cb->start = control->start;
cb->dump = control->dump;
cb->done = control->done;
cb->nlh = nlh;
@ -2927,6 +2928,9 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
mutex_unlock(nlk->cb_mutex);
if (cb->start)
cb->start(cb);
ret = netlink_dump(sk);
sock_put(sk);

16
net/netlink/genetlink.c
View File

@ -513,6 +513,20 @@ void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
}
EXPORT_SYMBOL(genlmsg_put);
static int genl_lock_start(struct netlink_callback *cb)
{
/* our ops are always const - netlink API doesn't propagate that */
const struct genl_ops *ops = cb->data;
int rc = 0;
if (ops->start) {
genl_lock();
rc = ops->start(cb);
genl_unlock();
}
return rc;
}
static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
/* our ops are always const - netlink API doesn't propagate that */
@ -577,6 +591,7 @@ static int genl_family_rcv_msg(struct genl_family *family,
.module = family->module,
/* we have const, but the netlink API doesn't */
.data = (void *)ops,
.start = genl_lock_start,
.dump = genl_lock_dumpit,
.done = genl_lock_done,
};
@ -588,6 +603,7 @@ static int genl_family_rcv_msg(struct genl_family *family,
} else {
struct netlink_dump_control c = {
.module = family->module,
.start = ops->start,
.dump = ops->dumpit,
.done = ops->done,
};