bpf, sockmap, udp: sk_prot needs inuse_idx set for proc stats

stable inclusion
from stable-5.10.54
commit 3b5b0afd8d97b0e98e5dc91526414e9d27c08027
bugzilla: 175586 https://gitee.com/openeuler/kernel/issues/I4DVDU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3b5b0afd8d97b0e98e5dc91526414e9d27c08027

--------------------------------

[ Upstream commit 54ea2f49 ]

The proc socket stats use sk_prot->inuse_idx value to record inuse sock
stats. We currently do not set this correctly from sockmap side. The
result is reading sock stats '/proc/net/sockstat' gives incorrect values.
The socket counter is incremented correctly, but because we don't set the
counter correctly when we replace sk_prot we may omit the decrement.

To get the correct inuse_idx value move the core_initcall that initializes
the UDP proto handlers to late_initcall. This way it is initialized after
UDP has the chance to assign the inuse_idx value from the register protocol
handler.

Fixes: edc6741c ("bpf: Add sockmap hooks for UDP sockets")
Signed-off-by: NJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210714154750.528206-1-jakub@cloudflare.comSigned-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/ipv4/udp_bpf.c

@@ -39,7 +39,7 @@ static int __init udp_bpf_v4_build_proto(void)
 	udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
 	return 0;
 }
-core_initcall(udp_bpf_v4_build_proto);
+late_initcall(udp_bpf_v4_build_proto);
 
 struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
 {