From d09b9e60e06d431b008a878c4b1d48d6cce816ef Mon Sep 17 00:00:00 2001 From: Priyaranjan Jha Date: Fri, 3 Nov 2017 17:46:55 -0700 Subject: [PATCH] tcp: fix DSACK-based undo on non-duplicate ACK Fixes DSACK-based undo when sender is in Open State and an ACK advances snd_una. Example scenario: - Sender goes into recovery and makes some spurious rtx. - It comes out of recovery and enters into open state. - It sends some more packets, let's say 4. - The receiver sends an ACK for the first two, but this ACK is lost. - The sender receives ack for first two, and DSACK for previous spurious rtx. Signed-off-by: Priyaranjan Jha Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Acked-by: Yousuk Seung Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5a87a00641d3..b2fc7163bd40 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -115,7 +115,7 @@ int sysctl_tcp_invalid_ratelimit __read_mostly = HZ/2; #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) #define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) -#define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE) +#define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE|FLAG_DSACKING_ACK) #define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED) #define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH) -- 2.20.1