[NET]: Move the filter releasing into a separate call

This is done merely as a preparation for the fix.

The sk_filter_uncharge() unaccounts the filter memory and calls
the sk_filter_release(), which in turn decrements the refcount
anf frees the filter.

The latter function will be required separately.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -922,14 +922,18 @@ static inline void sk_filter_rcu_free(struct rcu_head *rcu)
  *	Remove a filter from a socket and release its resources.
  */
 
-static inline void sk_filter_release(struct sock *sk, struct sk_filter *fp)
+static inline void sk_filter_release(struct sk_filter *fp)
+{
+	if (atomic_dec_and_test(&fp->refcnt))
+		call_rcu_bh(&fp->rcu, sk_filter_rcu_free);
+}
+
+static inline void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)
 {
 	unsigned int size = sk_filter_len(fp);
 
 	atomic_sub(size, &sk->sk_omem_alloc);
-
-	if (atomic_dec_and_test(&fp->refcnt))
-		call_rcu_bh(&fp->rcu, sk_filter_rcu_free);
+	sk_filter_release(fp);
 }
 
 static inline void sk_filter_charge(struct sock *sk, struct sk_filter *fp)

net/core/filter.c

@@ -429,7 +429,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 	}
 
 	if (fp)
-		sk_filter_release(sk, fp);
+		sk_filter_uncharge(sk, fp);
 	return err;
 }
 
@@ -442,7 +442,7 @@ int sk_detach_filter(struct sock *sk)
 	filter = rcu_dereference(sk->sk_filter);
 	if (filter) {
 		rcu_assign_pointer(sk->sk_filter, NULL);
-		sk_filter_release(sk, filter);
+		sk_filter_uncharge(sk, filter);
 		ret = 0;
 	}
 	rcu_read_unlock_bh();

net/core/sock.c

@@ -915,7 +915,7 @@ void sk_free(struct sock *sk)
 
 	filter = rcu_dereference(sk->sk_filter);
 	if (filter) {
-		sk_filter_release(sk, filter);
+		sk_filter_uncharge(sk, filter);
 		rcu_assign_pointer(sk->sk_filter, NULL);
 	}