From 28b24f90020fed8e8e3e8e20575f08c1cd06e54f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Sep 2023 20:28:15 +0000 Subject: net: implement lockless SO_MAX_PACING_RATE SO_MAX_PACING_RATE setsockopt() does not need to hold the socket lock, because sk->sk_pacing_rate readers can run fine if the value is changed by other threads, after adding READ_ONCE() accessors. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_bbr.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'net/ipv4/tcp_bbr.c') diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index 146792cd26fe..22358032dd48 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -258,7 +258,7 @@ static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain) u64 rate = bw; rate = bbr_rate_bytes_per_sec(sk, rate, gain); - rate = min_t(u64, rate, sk->sk_max_pacing_rate); + rate = min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate)); return rate; } @@ -278,7 +278,8 @@ static void bbr_init_pacing_rate_from_rtt(struct sock *sk) } bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT; do_div(bw, rtt_us); - sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain); + WRITE_ONCE(sk->sk_pacing_rate, + bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain)); } /* Pace using current bw estimate and a gain factor. */ @@ -290,14 +291,14 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) if (unlikely(!bbr->has_seen_rtt && tp->srtt_us)) bbr_init_pacing_rate_from_rtt(sk); - if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate) - sk->sk_pacing_rate = rate; + if (bbr_full_bw_reached(sk) || rate > READ_ONCE(sk->sk_pacing_rate)) + WRITE_ONCE(sk->sk_pacing_rate, rate); } /* override sysctl_tcp_min_tso_segs */ __bpf_kfunc static u32 bbr_min_tso_segs(struct sock *sk) { - return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; + return READ_ONCE(sk->sk_pacing_rate) < (bbr_min_tso_rate >> 3) ? 1 : 2; } static u32 bbr_tso_segs_goal(struct sock *sk) @@ -309,7 +310,7 @@ static u32 bbr_tso_segs_goal(struct sock *sk) * driver provided sk_gso_max_size. */ bytes = min_t(unsigned long, - sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift), + READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift), GSO_LEGACY_MAX_SIZE - 1 - MAX_TCP_HEADER); segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk)); -- cgit v1.2.3