diff --git a/include/linux/filter.h b/include/linux/filter.h
index 93a9792..9bde3ed 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -50,28 +50,32 @@
 #define sk_filter_proglen(fprog)			\
 		(fprog->len * sizeof(fprog->filter[0]))
 
-extern int sk_filter(struct sock *sk, struct sk_buff *skb);
-extern unsigned int sk_run_filter(const struct sk_buff *skb,
-				  const struct sock_filter *filter);
+int sk_filter(struct sock *sk, struct sk_buff *skb);
+unsigned int sk_run_filter(const struct sk_buff *skb,
+			   const struct sock_filter *filter);
 
-extern int sk_unattached_filter_create(struct sk_filter **pfp,
-				       struct sock_fprog *fprog);
-extern void sk_unattached_filter_destroy(struct sk_filter *fp);
+int sk_unattached_filter_create(struct sk_filter **pfp,
+				struct sock_fprog *fprog);
+void sk_unattached_filter_destroy(struct sk_filter *fp);
 
-extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
-extern int sk_detach_filter(struct sock *sk);
+int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
+int sk_detach_filter(struct sock *sk);
 
-extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
-extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
-extern void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to);
+int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
+int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
+		  unsigned int len);
+void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to);
+
+void sk_filter_charge(struct sock *sk, struct sk_filter *fp);
+void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 
 #ifdef CONFIG_BPF_JIT
 #include <stdarg.h>
 #include <linux/linkage.h>
 #include <linux/printk.h>
 
-extern void bpf_jit_compile(struct sk_filter *fp);
-extern void bpf_jit_free(struct sk_filter *fp);
+void bpf_jit_compile(struct sk_filter *fp);
+void bpf_jit_free(struct sk_filter *fp);
 
 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 				u32 pass, void *image)