netdev - [PATCH 4/5] genetlink: factor skb preparation out of ctrl

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Date:   Fri,  2 Oct 2020 11:09:43 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 4/5] genetlink: factor skb preparation out of ctrl_dumppolicy()

From: Johannes Berg <johannes.berg@...el.com>

We'll need this later for the per-op policy index dump.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
 net/netlink/genetlink.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 42777749d4d8..0ab9549e30ee 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1168,23 +1168,35 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
 					      op.maxattr);
 }
 
+static void *ctrl_dumppolicy_prep(struct sk_buff *skb,
+				  struct netlink_callback *cb)
+{
+	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
+	void *hdr;
+
+	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+			  cb->nlh->nlmsg_seq, &genl_ctrl,
+			  NLM_F_MULTI, CTRL_CMD_GETPOLICY);
+	if (!hdr)
+		return NULL;
+
+	if (nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, ctx->fam_id))
+		return NULL;
+
+	return hdr;
+}
+
 static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
 
 	while (netlink_policy_dump_loop(ctx->state)) {
-		void *hdr;
+		void *hdr = ctrl_dumppolicy_prep(skb, cb);
 		struct nlattr *nest;
 
-		hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
-				  cb->nlh->nlmsg_seq, &genl_ctrl,
-				  NLM_F_MULTI, CTRL_CMD_GETPOLICY);
 		if (!hdr)
 			goto nla_put_failure;
 
-		if (nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, ctx->fam_id))
-			goto nla_put_failure;
-
 		nest = nla_nest_start(skb, CTRL_ATTR_POLICY);
 		if (!nest)
 			goto nla_put_failure;
-- 
2.26.2