sock_map: Make sock_map_prog_update() static

It is only used within sock_map.c so can become static.
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210223184934.6054-7-xiyou.wangcong@gmail.com

include/linux/bpf.h

@@ -1779,8 +1779,6 @@ static inline void bpf_map_offload_map_free(struct bpf_map *map)
 #endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
 
 #if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)
-int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
-			 struct bpf_prog *old, u32 which);
 int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog);
 int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype);
 int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value, u64 flags);
@@ -1798,13 +1796,6 @@ static inline void bpf_sk_reuseport_detach(struct sock *sk)
 }
 
 #ifdef CONFIG_BPF_SYSCALL
-static inline int sock_map_prog_update(struct bpf_map *map,
-				       struct bpf_prog *prog,
-				       struct bpf_prog *old, u32 which)
-{
-	return -EOPNOTSUPP;
-}
-
 static inline int sock_map_get_from_fd(const union bpf_attr *attr,
 				       struct bpf_prog *prog)
 {

net/core/sock_map.c

@@ -24,6 +24,9 @@ struct bpf_stab {
 #define SOCK_CREATE_FLAG_MASK				\
 	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
 
+static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
+				struct bpf_prog *old, u32 which);
+
 static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
 {
 	struct bpf_stab *stab;
@@ -1444,8 +1447,8 @@ static struct sk_psock_progs *sock_map_progs(struct bpf_map *map)
 	return NULL;
 }
 
-int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
-			 struct bpf_prog *old, u32 which)
+static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
+				struct bpf_prog *old, u32 which)
 {
 	struct sk_psock_progs *progs = sock_map_progs(map);
 	struct bpf_prog **pprog;