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tcp: Fix data-races around sk_pacing_rate.

While reading sysctl_tcp_pacing_(ss|ca)_ratio, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers.

Kuniyuki Iwashima committed 4 years ago

Commit 59bf6c61 parent 3e7d18b1 file · +2 −2Browse files

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net/ipv4/tcp_input.c+2−2
@@ -910,9 +910,9 @@ static void tcp_update_pacing_rate(struct sock *sk) · 909 unmodified lines
910910 * end of slow start and should slow down.
911911 */
912912 if (tcp_snd_cwnd(tp) < tp->snd_ssthresh / 2)
913− rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio;
913+ rate *= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio);
914914 else
915− rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ca_ratio;
915+ rate *= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pacing_ca_ratio);
916916
917917 rate *= max(tcp_snd_cwnd(tp), tp->packets_out);
918918