This is a note to let you know that I've just added the patch titled tcp: fix rate_app_limited to default to 1 to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tcp-fix-rate_app_limited-to-default-to-1.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3a259eac136cee82d5ceca562ff3e983d5bf5c45 Author: David Morley <morleyd@xxxxxxxxxx> Date: Thu Jan 19 19:00:28 2023 +0000 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@xxxxxxxxxx> Signed-off-by: David Morley <morleyd@xxxxxxxxxx> Signed-off-by: Neal Cardwell <ncardwell@xxxxxxxxxx> Tested-by: David Morley <morleyd@xxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index fe1972aad279..51f34560a9d6 100644 --- 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;