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authorKuniyuki Iwashima <kuniyu@amazon.com>2022-07-18 19:26:48 +0200
committerDavid S. Miller <davem@davemloft.net>2022-07-20 11:14:50 +0200
commit4845b5713ab18a1bb6e31d1fbb4d600240b8b691 (patch)
tree3b1006f962476c31c415c8f357600aad22d32462
parenttcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts. (diff)
downloadlinux-4845b5713ab18a1bb6e31d1fbb4d600240b8b691.tar.xz
linux-4845b5713ab18a1bb6e31d1fbb4d600240b8b691.zip
tcp: Fix data-races around sysctl_tcp_slow_start_after_idle.
While reading sysctl_tcp_slow_start_after_idle, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 35089bb203f4 ("[TCP]: Add tcp_slow_start_after_idle sysctl.") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/tcp.h4
-rw-r--r--net/ipv4/tcp_output.c2
2 files changed, 3 insertions, 3 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6ee1fb4fb292..071735e10872 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1403,8 +1403,8 @@ static inline void tcp_slow_start_after_idle_check(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk);
s32 delta;
- if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out ||
- ca_ops->cong_control)
+ if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
+ tp->packets_out || ca_ops->cong_control)
return;
delta = tcp_jiffies32 - tp->lsndtime;
if (delta > inet_csk(sk)->icsk_rto)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 898fcdcb7989..51120407c570 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1898,7 +1898,7 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
if (tp->packets_out > tp->snd_cwnd_used)
tp->snd_cwnd_used = tp->packets_out;
- if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle &&
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) &&
(s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto &&
!ca_ops->cong_control)
tcp_cwnd_application_limited(sk);