tcp: fix rate_app_limited to default to 1

[ Upstream commit 300b655db1b5152d6101bcb6801d50899b20c2d6 ]

The initial default value of 0 for tp->rate_app_limited was incorrect,
since a flow is indeed application-limited until it first sends
data. Fixing the default to be 1 is generally correct but also
specifically will help user-space applications avoid using the initial
tcpi_delivery_rate value of 0 that persists until the connection has
some non-zero bandwidth sample.

Fixes: eb8329e0a04d ("tcp: export data delivery rate")
Suggested-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David Morley <morleyd@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Tested-by: David Morley <morleyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index fe1972a..51f3456 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -439,6 +439,7 @@ void tcp_init_sock(struct sock *sk)
 
        /* There's a bubble in the pipe until at least the first ACK. */
        tp->app_limited = ~0U;
+       tp->rate_app_limited = 1;
 
        /* See draft-stevens-tcpca-spec-01 for discussion of the
         * initialization of these values.
@@ -3066,6 +3067,7 @@ int tcp_disconnect(struct sock *sk, int flags)
        tp->last_oow_ack_time = 0;
        /* There's a bubble in the pipe until at least the first ACK. */
        tp->app_limited = ~0U;
+       tp->rate_app_limited = 1;
        tp->rack.mstamp = 0;
        tp->rack.advanced = 0;
        tp->rack.reo_wnd_steps = 1;