[NET]: skb_trim audit

I found a few more spots where pskb_trim_rcsum could be used but were not.
This patch changes them to use it.

Also, sk_filter can get paged skb data.  Therefore we must use pskb_trim
instead of skb_trim.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index 75b0e97..96565ff 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -873,10 +873,7 @@
 		if (filter) {
 			unsigned int pkt_len = sk_run_filter(skb, filter->insns,
 							     filter->len);
-			if (!pkt_len)
-				err = -EPERM;
-			else
-				skb_trim(skb, pkt_len);
+			err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
 		}
 
 		if (needlock)