net: netlink: add the case when nlh is NULL

Add the case when nlh is NULL in nlmsg_report(),
so that the caller doesn't need to deal with this case.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netlink.h

@@ -885,7 +885,7 @@ static inline int nlmsg_validate_deprecated(const struct nlmsghdr *nlh,
  */
 static inline int nlmsg_report(const struct nlmsghdr *nlh)
 {
-	return !!(nlh->nlmsg_flags & NLM_F_ECHO);
+	return nlh ? !!(nlh->nlmsg_flags & NLM_F_ECHO) : 0;
 }
 
 /**

net/core/rtnetlink.c

@@ -726,12 +726,8 @@ void rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid, u32 group,
 		 struct nlmsghdr *nlh, gfp_t flags)
 {
 	struct sock *rtnl = net->rtnl;
-	int report = 0;
 
-	if (nlh)
-		report = nlmsg_report(nlh);
-
-	nlmsg_notify(rtnl, skb, pid, group, report, flags);
+	nlmsg_notify(rtnl, skb, pid, group, nlmsg_report(nlh), flags);
 }
 EXPORT_SYMBOL(rtnl_notify);
 

net/netlink/genetlink.c

@@ -1485,6 +1485,7 @@ int genlmsg_multicast_allns(const struct genl_family *family,
 {
 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
 		return -EINVAL;
+
 	group = family->mcgrp_offset + group;
 	return genlmsg_mcast(skb, portid, group, flags);
 }
@@ -1495,14 +1496,12 @@ void genl_notify(const struct genl_family *family, struct sk_buff *skb,
 {
 	struct net *net = genl_info_net(info);
 	struct sock *sk = net->genl_sock;
-	int report = 0;
-
-	if (info->nlhdr)
-		report = nlmsg_report(info->nlhdr);
 
 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
 		return;
+
 	group = family->mcgrp_offset + group;
-	nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
+	nlmsg_notify(sk, skb, info->snd_portid, group,
+		     nlmsg_report(info->nlhdr), flags);
 }
 EXPORT_SYMBOL(genl_notify);