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tcp: Fix a data-race around sysctl_tcp_comp_sack_delay_ns.

While reading sysctl_tcp_comp_sack_delay_ns, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader.

Kuniyuki Iwashima committed 4 years ago

Commit 4866b2b1 parent 02739541 file · +2 −1Browse files

Unified · Split

net/ipv4/tcp_input.c+2−1
@@ -5542,7 +5542,8 @@ send_now: · 5541 unmodified lines
55425542 if (tp->srtt_us && tp->srtt_us < rtt)
55435543 rtt = tp->srtt_us;
55445544
5545− delay = min_t(unsigned long, sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns,
5545+ delay = min_t(unsigned long,
5546+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns),
55465547 rtt * (NSEC_PER_USEC >> 3)/20);
55475548 sock_hold(sk);
55485549 hrtimer_start_range_ns(&tp->compressed_ack_timer, ns_to_ktime(delay),