[NETLINK]: Use nlmsg_trim() where appropriate

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index ea0a491..48027df 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -62,6 +62,7 @@
 #include <linux/netfilter_ipv4.h>
 #include <net/ipip.h>
 #include <net/checksum.h>
+#include <net/netlink.h>
 
 #if defined(CONFIG_IP_PIMSM_V1) || defined(CONFIG_IP_PIMSM_V2)
 #define CONFIG_IP_PIMSM	1
@@ -1570,7 +1571,7 @@
 	return 1;
 
 rtattr_failure:
-	skb_trim(skb, b - skb->data);
+	nlmsg_trim(skb, b);
 	return -EMSGSIZE;
 }