netdev - [PATCH bpf-next v3 3/5] tcp: simplify tcp_set_congestion

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Date:   Thu, 10 Sep 2020 15:35:34 -0400
From:   Neal Cardwell <ncardwell.kernel@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     netdev@...r.kernel.org, Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>, Kevin Yang <yyd@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Lawrence Brakmo <brakmo@...com>
Subject: [PATCH bpf-next v3 3/5] tcp: simplify tcp_set_congestion_control(): always reinitialize

From: Neal Cardwell <ncardwell@...gle.com>

Now that the previous patches ensure that all call sites for
tcp_set_congestion_control() want to initialize congestion control, we
can simplify tcp_set_congestion_control() by removing the reinit
argument and the code to support it.

Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Acked-by: Yuchung Cheng <ycheng@...gle.com>
Acked-by: Kevin Yang <yyd@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Lawrence Brakmo <brakmo@...com>
---
 include/net/tcp.h   |  2 +-
 net/core/filter.c   |  3 +--
 net/ipv4/tcp.c      |  2 +-
 net/ipv4/tcp_cong.c | 11 ++---------
 4 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index e85d564446c6..f857146c17a5 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1104,7 +1104,7 @@ void tcp_get_available_congestion_control(char *buf, size_t len);
 void tcp_get_allowed_congestion_control(char *buf, size_t len);
 int tcp_set_allowed_congestion_control(char *allowed);
 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
-			       bool reinit, bool cap_net_admin);
+			       bool cap_net_admin);
 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
 
diff --git a/net/core/filter.c b/net/core/filter.c
index 067f6759a68f..e89d6d7da03c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4451,8 +4451,7 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 			strncpy(name, optval, min_t(long, optlen,
 						    TCP_CA_NAME_MAX-1));
 			name[TCP_CA_NAME_MAX-1] = 0;
-			ret = tcp_set_congestion_control(sk, name, false,
-							 true, true);
+			ret = tcp_set_congestion_control(sk, name, false, true);
 		} else {
 			struct inet_connection_sock *icsk = inet_csk(sk);
 			struct tcp_sock *tp = tcp_sk(sk);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 7360d3db2b61..e58ab9db73ff 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3050,7 +3050,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		name[val] = 0;
 
 		lock_sock(sk);
-		err = tcp_set_congestion_control(sk, name, true, true,
+		err = tcp_set_congestion_control(sk, name, true,
 						 ns_capable(sock_net(sk)->user_ns,
 							    CAP_NET_ADMIN));
 		release_sock(sk);
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index d18d7a1ce4ce..a9b0fb52a1ec 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -341,7 +341,7 @@ int tcp_set_allowed_congestion_control(char *val)
  * already initialized.
  */
 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
-			       bool reinit, bool cap_net_admin)
+			       bool cap_net_admin)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	const struct tcp_congestion_ops *ca;
@@ -365,15 +365,8 @@ int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
 	if (!ca) {
 		err = -ENOENT;
 	} else if (!load) {
-		const struct tcp_congestion_ops *old_ca = icsk->icsk_ca_ops;
-
 		if (bpf_try_module_get(ca, ca->owner)) {
-			if (reinit) {
-				tcp_reinit_congestion_control(sk, ca);
-			} else {
-				icsk->icsk_ca_ops = ca;
-				bpf_module_put(old_ca, old_ca->owner);
-			}
+			tcp_reinit_congestion_control(sk, ca);
 		} else {
 			err = -EBUSY;
 		}
-- 
2.28.0.618.gf4bc123cb7-goog