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authorEric Dumazet <edumazet@google.com>2022-04-06 02:35:38 +0300
committerJakub Kicinski <kuba@kernel.org>2022-04-06 22:05:41 +0300
commit40570375356c874b1578e05c1dcc3ff7c1322dbe (patch)
tree54c7a52bfdd4e302f877e93dc94adb09cfa3aac4 /include/net/tcp.h
parent487dc3ca60e3e420d54bcc613cb49e8e85f34569 (diff)
downloadlinux-40570375356c874b1578e05c1dcc3ff7c1322dbe.tar.xz
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 'include/net/tcp.h')
-rw-r--r--include/net/tcp.h19
1 files changed, 15 insertions, 4 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 70ca4a5e330a..54aa2f02bb63 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1207,9 +1207,20 @@ static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
#define TCP_INFINITE_SSTHRESH 0x7fffffff
+static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
+{
+ return tp->snd_cwnd;
+}
+
+static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
+{
+ WARN_ON_ONCE((int)val <= 0);
+ tp->snd_cwnd = val;
+}
+
static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
{
- return tp->snd_cwnd < tp->snd_ssthresh;
+ return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
}
static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
@@ -1235,8 +1246,8 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
return tp->snd_ssthresh;
else
return max(tp->snd_ssthresh,
- ((tp->snd_cwnd >> 1) +
- (tp->snd_cwnd >> 2)));
+ ((tcp_snd_cwnd(tp) >> 1) +
+ (tcp_snd_cwnd(tp) >> 2)));
}
/* Use define here intentionally to get WARN_ON location shown at the caller */
@@ -1278,7 +1289,7 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk)
/* If in slow start, ensure cwnd grows to twice what was ACKed. */
if (tcp_in_slow_start(tp))
- return tp->snd_cwnd < 2 * tp->max_packets_out;
+ return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
return tp->is_cwnd_limited;
}