nfsd4: remove pointless strdup_if_nonnull

kstrdup() already checks for NULL.

(Brought to our attention by Jason Yann noticing (from sparse output)
that it should have been declared static.)
Signed-off-by: NeilBrown <neilb@suse.com>
Reported-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -1912,28 +1912,15 @@ static void copy_clid(struct nfs4_client *target, struct nfs4_client *source)
 	target->cl_clientid.cl_id = source->cl_clientid.cl_id; 
 }
 
-int strdup_if_nonnull(char **target, char *source)
-{
-	if (source) {
-		*target = kstrdup(source, GFP_KERNEL);
-		if (!*target)
-			return -ENOMEM;
-	} else
-		*target = NULL;
-	return 0;
-}
-
 static int copy_cred(struct svc_cred *target, struct svc_cred *source)
 {
-	int ret;
+	target->cr_principal = kstrdup(source->cr_principal, GFP_KERNEL);
+	target->cr_raw_principal = kstrdup(source->cr_raw_principal,
+								GFP_KERNEL);
+	if ((source->cr_principal && ! target->cr_principal) ||
+	    (source->cr_raw_principal && ! target->cr_raw_principal))
+		return -ENOMEM;
 
-	ret = strdup_if_nonnull(&target->cr_principal, source->cr_principal);
-	if (ret)
-		return ret;
-	ret = strdup_if_nonnull(&target->cr_raw_principal,
-					source->cr_raw_principal);
-	if (ret)
-		return ret;
 	target->cr_flavor = source->cr_flavor;
 	target->cr_uid = source->cr_uid;
 	target->cr_gid = source->cr_gid;