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authorEric Dumazet <edumazet@google.com>2022-04-05 16:35:38 -0700
committerJakub Kicinski <kuba@kernel.org>2022-04-06 12:05:41 -0700
commit40570375356c874b1578e05c1dcc3ff7c1322dbe (patch)
tree54c7a52bfdd4e302f877e93dc94adb09cfa3aac4 /net/ipv4/tcp_input.c
parent487dc3ca60e3e420d54bcc613cb49e8e85f34569 (diff)
tcp: add accessors to read/set tp->snd_cwnd
We had various bugs over the years with code breaking the assumption that tp->snd_cwnd is greater than zero. Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcp_cwnd_reduction") can trigger, and without a repro we would have to spend considerable time finding the bug. Instead of complaining too late, we want to catch where and when tp->snd_cwnd is set to an illegal value. Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c36
1 files changed, 18 insertions, 18 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2088f93fa37b..1595b76ea2be 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -414,7 +414,7 @@ static void tcp_sndbuf_expand(struct sock *sk)
per_mss = roundup_pow_of_two(per_mss) +
SKB_DATA_ALIGN(sizeof(struct sk_buff));
- nr_segs = max_t(u32, TCP_INIT_CWND, tp->snd_cwnd);
+ nr_segs = max_t(u32, TCP_INIT_CWND, tcp_snd_cwnd(tp));
nr_segs = max_t(u32, nr_segs, tp->reordering + 1);
/* Fast Recovery (RFC 5681 3.2) :
@@ -909,12 +909,12 @@ static void tcp_update_pacing_rate(struct sock *sk)
* If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching
* end of slow start and should slow down.
*/
- if (tp->snd_cwnd < tp->snd_ssthresh / 2)
+ if (tcp_snd_cwnd(tp) < tp->snd_ssthresh / 2)
rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio;
else
rate *= sock_net(sk)->ipv4.sysctl_tcp_pacing_ca_ratio;
- rate *= max(tp->snd_cwnd, tp->packets_out);
+ rate *= max(tcp_snd_cwnd(tp), tp->packets_out);
if (likely(tp->srtt_us))
do_div(rate, tp->srtt_us);
@@ -2147,12 +2147,12 @@ void tcp_enter_loss(struct sock *sk)
!after(tp->high_seq, tp->snd_una) ||
(icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
tp->prior_ssthresh = tcp_current_ssthresh(sk);
- tp->prior_cwnd = tp->snd_cwnd;
+ tp->prior_cwnd = tcp_snd_cwnd(tp);
tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
tcp_ca_event(sk, CA_EVENT_LOSS);
tcp_init_undo(tp);
}
- tp->snd_cwnd = tcp_packets_in_flight(tp) + 1;
+ tcp_snd_cwnd_set(tp, tcp_packets_in_flight(tp) + 1);
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_jiffies32;
@@ -2458,7 +2458,7 @@ static void DBGUNDO(struct sock *sk, const char *msg)
pr_debug("Undo %s %pI4/%u c%u l%u ss%u/%u p%u\n",
msg,
&inet->inet_daddr, ntohs(inet->inet_dport),
- tp->snd_cwnd, tcp_left_out(tp),
+ tcp_snd_cwnd(tp), tcp_left_out(tp),
tp->snd_ssthresh, tp->prior_ssthresh,
tp->packets_out);
}
@@ -2467,7 +2467,7 @@ static void DBGUNDO(struct sock *sk, const char *msg)
pr_debug("Undo %s %pI6/%u c%u l%u ss%u/%u p%u\n",
msg,
&sk->sk_v6_daddr, ntohs(inet->inet_dport),
- tp->snd_cwnd, tcp_left_out(tp),
+ tcp_snd_cwnd(tp), tcp_left_out(tp),
tp->snd_ssthresh, tp->prior_ssthresh,
tp->packets_out);
}
@@ -2492,7 +2492,7 @@ static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
if (tp->prior_ssthresh) {
const struct inet_connection_sock *icsk = inet_csk(sk);
- tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk);
+ tcp_snd_cwnd_set(tp, icsk->icsk_ca_ops->undo_cwnd(sk));
if (tp->prior_ssthresh > tp->snd_ssthresh) {
tp->snd_ssthresh = tp->prior_ssthresh;
@@ -2599,7 +2599,7 @@ static void tcp_init_cwnd_reduction(struct sock *sk)
tp->high_seq = tp->snd_nxt;
tp->tlp_high_seq = 0;
tp->snd_cwnd_cnt = 0;
- tp->prior_cwnd = tp->snd_cwnd;
+ tp->prior_cwnd = tcp_snd_cwnd(tp);
tp->prr_delivered = 0;
tp->prr_out = 0;
tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
@@ -2629,7 +2629,7 @@ void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost,
}
/* Force a fast retransmit upon entering fast recovery */
sndcnt = max(sndcnt, (tp->prr_out ? 0 : 1));
- tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
+ tcp_snd_cwnd_set(tp, tcp_packets_in_flight(tp) + sndcnt);
}
static inline void tcp_end_cwnd_reduction(struct sock *sk)
@@ -2642,7 +2642,7 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH &&
(inet_csk(sk)->icsk_ca_state == TCP_CA_CWR || tp->undo_marker)) {
- tp->snd_cwnd = tp->snd_ssthresh;
+ tcp_snd_cwnd_set(tp, tp->snd_ssthresh);
tp->snd_cwnd_stamp = tcp_jiffies32;
}
tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR);
@@ -2709,9 +2709,9 @@ static void tcp_mtup_probe_success(struct sock *sk)
/* FIXME: breaks with very large cwnd */
tp->prior_ssthresh = tcp_current_ssthresh(sk);
- tp->snd_cwnd = tp->snd_cwnd *
- tcp_mss_to_mtu(sk, tp->mss_cache) /
- icsk->icsk_mtup.probe_size;
+ tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) *
+ tcp_mss_to_mtu(sk, tp->mss_cache) /
+ icsk->icsk_mtup.probe_size);
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_jiffies32;
tp->snd_ssthresh = tcp_current_ssthresh(sk);
@@ -3034,7 +3034,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
tp->snd_una == tp->mtu_probe.probe_seq_start) {
tcp_mtup_probe_failed(sk);
/* Restores the reduction we did in tcp_mtup_probe() */
- tp->snd_cwnd++;
+ tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
tcp_simple_retransmit(sk);
return;
}
@@ -5436,7 +5436,7 @@ static bool tcp_should_expand_sndbuf(struct sock *sk)
return false;
/* If we filled the congestion window, do not expand. */
- if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
+ if (tcp_packets_in_flight(tp) >= tcp_snd_cwnd(tp))
return false;
return true;
@@ -5998,9 +5998,9 @@ void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb)
* retransmission has occurred.
*/
if (tp->total_retrans > 1 && tp->undo_marker)
- tp->snd_cwnd = 1;
+ tcp_snd_cwnd_set(tp, 1);
else
- tp->snd_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk));
+ tcp_snd_cwnd_set(tp, tcp_init_cwnd(tp, __sk_dst_get(sk)));
tp->snd_cwnd_stamp = tcp_jiffies32;
bpf_skops_established(sk, bpf_op, skb);