From: Soheil Hassas Yeganeh <soh...@google.com>
Add documentation to the tcp_ca_state enum, since this enum is
exposed in uapi.
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
Cc: Sowmini Varadhan <sowmin...@gmail.com>
---
include/uapi/linux/tcp.h | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8bb6cc5f3235..b521464ea962 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -160,15 +160,42 @@ enum {
#define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT
*/
#define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */
+/*
+ * Sender's congestion state indicating normal or abnormal situations
+ * in the last round of packets sent. The state is driven by the ACK
+ * information and timer events.
+ */
enum tcp_ca_state {
+ /*
+ * Nothing bad has been observed recently.
+ * No apparent reordering, packet loss, or ECN marks.
+ */
TCP_CA_Open = 0,
#define TCPF_CA_Open (1<<TCP_CA_Open)
+ /*
+ * The sender enters disordered state when it has received DUPACKs or
+ * SACKs in the last round of packets sent. This could be due to packet
+ * loss or reordering but needs further information to confirm packets
+ * have been lost.
+ */
TCP_CA_Disorder = 1,
#define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
+ /*
+ * The sender enters Congestion Window Reduction (CWR) state when it
+ * has received ACKs with ECN-ECE marks, or has experienced congestion
+ * or packet discard on the sender host (e.g. qdisc).
+ */
TCP_CA_CWR = 2,
#define TCPF_CA_CWR (1<<TCP_CA_CWR)
+ /*
+ * The sender is in fast recovery and retransmitting lost packets,
+ * typically triggered by ACK events.
+ */
TCP_CA_Recovery = 3,
#define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
+ /*
+ * The sender is in loss recovery triggered by retransmission timeout.
+ */
TCP_CA_Loss = 4
#define TCPF_CA_Loss (1<<TCP_CA_Loss)
};
--
2.21.0.392.gf8f6787159e-goog
