Add documentation to the tcp_ca_state enum, since this enum is exposed in uapi.
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| @@ -160,15 +160,42 @@ enum { · 159 unmodified lines | ||
| 160 | 160 | #define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT */ |
| 161 | 161 | #define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */ |
| 162 | 162 | |
| 163 | +/* | |
| 164 | + * Sender's congestion state indicating normal or abnormal situations | |
| 165 | + * in the last round of packets sent. The state is driven by the ACK | |
| 166 | + * information and timer events. | |
| 167 | + */ | |
| 163 | 168 | enum tcp_ca_state { |
| 169 | + /* | |
| 170 | + * Nothing bad has been observed recently. | |
| 171 | + * No apparent reordering, packet loss, or ECN marks. | |
| 172 | + */ | |
| 164 | 173 | TCP_CA_Open = 0, |
| 165 | 174 | #define TCPF_CA_Open (1<<TCP_CA_Open) |
| 175 | + /* | |
| 176 | + * The sender enters disordered state when it has received DUPACKs or | |
| 177 | + * SACKs in the last round of packets sent. This could be due to packet | |
| 178 | + * loss or reordering but needs further information to confirm packets | |
| 179 | + * have been lost. | |
| 180 | + */ | |
| 166 | 181 | TCP_CA_Disorder = 1, |
| 167 | 182 | #define TCPF_CA_Disorder (1<<TCP_CA_Disorder) |
| 183 | + /* | |
| 184 | + * The sender enters Congestion Window Reduction (CWR) state when it | |
| 185 | + * has received ACKs with ECN-ECE marks, or has experienced congestion | |
| 186 | + * or packet discard on the sender host (e.g. qdisc). | |
| 187 | + */ | |
| 168 | 188 | TCP_CA_CWR = 2, |
| 169 | 189 | #define TCPF_CA_CWR (1<<TCP_CA_CWR) |
| 190 | + /* | |
| 191 | + * The sender is in fast recovery and retransmitting lost packets, | |
| 192 | + * typically triggered by ACK events. | |
| 193 | + */ | |
| 170 | 194 | TCP_CA_Recovery = 3, |
| 171 | 195 | #define TCPF_CA_Recovery (1<<TCP_CA_Recovery) |
| 196 | + /* | |
| 197 | + * The sender is in loss recovery triggered by retransmission timeout. | |
| 198 | + */ | |
| 172 | 199 | TCP_CA_Loss = 4 |
| 173 | 200 | #define TCPF_CA_Loss (1<<TCP_CA_Loss) |
| 174 | 201 | }; |