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/core/sock.c | 40 +++++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 19 deletions(-) (limited to 'net/core/sock.c') diff --git a/net/core/sock.c b/net/core/sock.c index 408081549bd7..4254ed0e4817 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1160,6 +1160,27 @@ int sk_setsockopt(struct sock *sk, int level, int optname, WRITE_ONCE(sk->sk_busy_poll_budget, val); return 0; #endif + case SO_MAX_PACING_RATE: + { + unsigned long ulval = (val == ~0U) ? ~0UL : (unsigned int)val; + unsigned long pacing_rate; + + if (sizeof(ulval) != sizeof(val) && + optlen >= sizeof(ulval) && + copy_from_sockptr(&ulval, optval, sizeof(ulval))) { + return -EFAULT; + } + if (ulval != ~0UL) + cmpxchg(&sk->sk_pacing_status, + SK_PACING_NONE, + SK_PACING_NEEDED); + /* Pairs with READ_ONCE() from sk_getsockopt() */ + WRITE_ONCE(sk->sk_max_pacing_rate, ulval); + pacing_rate = READ_ONCE(sk->sk_pacing_rate); + if (ulval < pacing_rate) + WRITE_ONCE(sk->sk_pacing_rate, ulval); + return 0; + } } sockopt_lock_sock(sk); @@ -1423,25 +1444,6 @@ set_sndbuf: break; - case SO_MAX_PACING_RATE: - { - unsigned long ulval = (val == ~0U) ? ~0UL : (unsigned int)val; - - if (sizeof(ulval) != sizeof(val) && - optlen >= sizeof(ulval) && - copy_from_sockptr(&ulval, optval, sizeof(ulval))) { - ret = -EFAULT; - break; - } - if (ulval != ~0UL) - cmpxchg(&sk->sk_pacing_status, - SK_PACING_NONE, - SK_PACING_NEEDED); - /* Pairs with READ_ONCE() from sk_getsockopt() */ - WRITE_ONCE(sk->sk_max_pacing_rate, ulval); - sk->sk_pacing_rate = min(sk->sk_pacing_rate, ulval); - break; - } case SO_INCOMING_CPU: reuseport_update_incoming_cpu(sk, val); break; -- cgit