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Mon, 17 Mar 2025 05:03:25 -0700 (PDT) Received: from KERNELXING-MB0.tencent.com ([43.132.141.24]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-225c6bd4e02sm73045835ad.226.2025.03.17.05.03.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Mar 2025 05:03:25 -0700 (PDT) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, ncardwell@google.com, kuniyu@amazon.com, dsahern@kernel.org Cc: netdev@vger.kernel.org, Jason Xing Subject: [PATCH net-next v4 2/2] tcp: support TCP_DELACK_MAX_US for set/getsockopt use Date: Mon, 17 Mar 2025 20:03:14 +0800 Message-Id: <20250317120314.41404-3-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20250317120314.41404-1-kerneljasonxing@gmail.com> References: <20250317120314.41404-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Support adjusting/reading delayed ack max for socket level by using set/getsockopt(). This option aligns with TCP_BPF_DELACK_MAX usage. Considering that bpf option was implemented before this patch, so we need to use a standalone new option for pure tcp set/getsockopt() use. Add WRITE_ONCE/READ_ONCE() to prevent data-race if setsockopt() happens to write one value to icsk_delack_max while icsk_delack_max is being read. Signed-off-by: Jason Xing --- include/uapi/linux/tcp.h | 1 + net/ipv4/tcp.c | 13 ++++++++++++- net/ipv4/tcp_output.c | 2 +- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index b2476cf7058e..2377e22f2c4b 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -138,6 +138,7 @@ enum { #define TCP_IS_MPTCP 43 /* Is MPTCP being used? */ #define TCP_RTO_MAX_MS 44 /* max rto time in ms */ #define TCP_RTO_MIN_US 45 /* min rto time in us */ +#define TCP_DELACK_MAX_US 46 /* max delayed ack time in us */ #define TCP_REPAIR_ON 1 #define TCP_REPAIR_OFF 0 diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index b89c1b676b8e..578e79024955 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3353,7 +3353,7 @@ int tcp_disconnect(struct sock *sk, int flags) icsk->icsk_probes_tstamp = 0; icsk->icsk_rto = TCP_TIMEOUT_INIT; WRITE_ONCE(icsk->icsk_rto_min, TCP_RTO_MIN); - icsk->icsk_delack_max = TCP_DELACK_MAX; + WRITE_ONCE(icsk->icsk_delack_max, TCP_DELACK_MAX); tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; tcp_snd_cwnd_set(tp, TCP_INIT_CWND); tp->snd_cwnd_cnt = 0; @@ -3841,6 +3841,14 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname, WRITE_ONCE(inet_csk(sk)->icsk_rto_min, rto_min); return 0; } + case TCP_DELACK_MAX_US: { + int delack_max = usecs_to_jiffies(val); + + if (delack_max > TCP_DELACK_MAX || delack_max < TCP_TIMEOUT_MIN) + return -EINVAL; + WRITE_ONCE(inet_csk(sk)->icsk_delack_max, delack_max); + return 0; + } } sockopt_lock_sock(sk); @@ -4683,6 +4691,9 @@ int do_tcp_getsockopt(struct sock *sk, int level, case TCP_RTO_MIN_US: val = jiffies_to_usecs(READ_ONCE(inet_csk(sk)->icsk_rto_min)); break; + case TCP_DELACK_MAX_US: + val = jiffies_to_usecs(READ_ONCE(inet_csk(sk)->icsk_delack_max)); + break; default: return -ENOPROTOOPT; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 24e56bf96747..65aa26d65987 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -4179,7 +4179,7 @@ u32 tcp_delack_max(const struct sock *sk) { u32 delack_from_rto_min = max(tcp_rto_min(sk), 2) - 1; - return min(inet_csk(sk)->icsk_delack_max, delack_from_rto_min); + return min(READ_ONCE(inet_csk(sk)->icsk_delack_max), delack_from_rto_min); } /* Send out a delayed ack, the caller does the policy checking -- 2.43.5