netdev - [PATCH bpf v4 2/2] bpf, sockmap: sk_prot needs inuse

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Message-Id: <20210712195546.423990-3-john.fastabend@gmail.com>
Date:   Mon, 12 Jul 2021 12:55:46 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     ast@...nel.org, jakub@...udflare.com, daniel@...earbox.net,
        andriin@...com, xiyou.wangcong@...il.com
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        john.fastabend@...il.com
Subject: [PATCH bpf v4 2/2] bpf, sockmap: sk_prot needs inuse_idx set for proc stats

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 tcp/udp proto handlers to late_initcall. This way it is initialized
after TCP/UDP has the chance to assign the inuse_idx value from the
register protocol handler.

Suggested-by: Jakub Sitnicki <jakub@...udflare.com>
Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 net/ipv4/tcp_bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index f26916a62f25..d3e9386b493e 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -503,7 +503,7 @@ static int __init tcp_bpf_v4_build_proto(void)
 	tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
 	return 0;
 }
-core_initcall(tcp_bpf_v4_build_proto);
+late_initcall(tcp_bpf_v4_build_proto);

 static int tcp_bpf_assert_proto_ops(struct proto *ops)
 {
-- 
2.25.1