genetlink: add a structure for dump state

Whenever netlink dump uses more than 2 cb->args[] entries
code gets hard to read. We're about to add more state to
ctrl_dumppolicy() so create a structure.

Since the structure is typed and clearly named we can remove
the local fam_id variable and use ctx->fam_id directly.

v3:
 - rebase onto explicit free fix
v1:
 - s/nl_policy_dump/netlink_policy_dump_state/
 - forward declare struct netlink_policy_dump_state,
   and move from passing unsigned long to actual pointer type
 - add build bug on
 - u16 fam_id
 - s/args/ctx/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/include/net/netlink.h b/include/net/netlink.h
index 9e7eca961a98..00258590f2cb 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1935,11 +1935,14 @@ void nla_get_range_unsigned(const struct nla_policy *pt,
 void nla_get_range_signed(const struct nla_policy *pt,
 			  struct netlink_range_validation_signed *range);
 
+struct netlink_policy_dump_state;
+
 int netlink_policy_dump_start(const struct nla_policy *policy,
 			      unsigned int maxtype,
-			      unsigned long *state);
-bool netlink_policy_dump_loop(unsigned long state);
-int netlink_policy_dump_write(struct sk_buff *skb, unsigned long state);
-void netlink_policy_dump_free(unsigned long state);
+			      struct netlink_policy_dump_state **state);
+bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state);
+int netlink_policy_dump_write(struct sk_buff *skb,
+			      struct netlink_policy_dump_state *state);
+void netlink_policy_dump_free(struct netlink_policy_dump_state *state);
 
 #endif