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 <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/netlink.h

···
  */
 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

···
 		 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

···
 {
 	if (WARN_ON_ONCE(group >= family->n_mcgrps))
 		return -EINVAL;
+
 	group = family->mcgrp_offset + group;
 	return genlmsg_mcast(skb, portid, group, flags);
 }
···
 {
 	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);