From e9d9da91548b21e189fcd0259a0f2d26d1afc509 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 17 Mar 2023 15:55:39 +0000 Subject: tcp: preserve const qualifier in tcp_sk() We can change tcp_sk() to propagate its argument const qualifier, thanks to container_of_const(). We have two places where a const sock pointer has to be upgraded to a write one. We have been using const qualifier for lockless listeners to clearly identify points where writes could happen. Add tcp_sk_rw() helper to better document these. tcp_inbound_md5_hash(), __tcp_grow_window(), tcp_reset_check() and tcp_rack_reo_wnd() get an additional const qualififer for their @tp local variables. smc_check_reset_syn_req() also needs a similar change. Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b1e743b39a83..cfe128b81a01 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -4127,8 +4127,13 @@ int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) if (!res) { TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); - if (unlikely(tcp_passive_fastopen(sk))) - tcp_sk(sk)->total_retrans++; + if (unlikely(tcp_passive_fastopen(sk))) { + /* sk has const attribute because listeners are lockless. + * However in this case, we are dealing with a passive fastopen + * socket thus we can change total_retrans value. + */ + tcp_sk_rw(sk)->total_retrans++; + } trace_tcp_retransmit_synack(sk, req); } return res; -- cgit