Thread (26 messages) flat view 26 messages, 4 authors, 2026-01-23

Re: [PATCH v10 net-next 13/15] tcp: accecn: add tcpi_ecn_mode and tcpi_option2 in tcp_info

From: Eric Dumazet <edumazet@google.com>
Date: 2026-01-21 14:58:07
Also in: bpf, linux-doc, linux-kselftest

On Wed, Jan 21, 2026 at 3:32 PM [off-list ref] wrote:
From: Chia-Yu Chang <redacted>

Add 2-bit tcpi_ecn_mode feild within tcp_info to indicate which ECN
mode is negotiated: ECN_MODE_DISABLED, ECN_MODE_RFC3168, ECN_MODE_ACCECN,
or ECN_MODE_PENDING. This is done by utilizing available bits from
tcpi_accecn_opt_seen (reduced from 16 bits to 2 bits) and
tcpi_accecn_fail_mode (reduced from 16 bits to 4 bits).

Also, an extra 24-bit tcpi_options2 field is identified to represent
newer options and connection features, as all 8 bits of tcpi_options
field have been used.

Signed-off-by: Chia-Yu Chang <redacted>
Co-developed-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
---
 +
quoted hunk ↗ jump to hunk
 struct tcp_info {
        __u8    tcpi_state;
        __u8    tcpi_ca_state;
@@ -316,15 +334,17 @@ struct tcp_info {
                                         * in milliseconds, including any
                                         * unfinished recovery.
                                         */
-       __u32   tcpi_received_ce;    /* # of CE marks received */
+       __u32   tcpi_received_ce;    /* # of CE marked segments received */
        __u32   tcpi_delivered_e1_bytes;  /* Accurate ECN byte counters */
        __u32   tcpi_delivered_e0_bytes;
        __u32   tcpi_delivered_ce_bytes;
        __u32   tcpi_received_e1_bytes;
        __u32   tcpi_received_e0_bytes;
        __u32   tcpi_received_ce_bytes;
-       __u16   tcpi_accecn_fail_mode;
-       __u16   tcpi_accecn_opt_seen;
+       __u32   tcpi_ecn_mode:2,
+               tcpi_accecn_opt_seen:2,
+               tcpi_accecn_fail_mode:4,
+               tcpi_options2:24;
 };
I guess this is fine, iproute2 got no support yet for
tcpi_accecn_fail_mode / tcpi_accecn_opt_seen

Reviewed-by: Eric Dumazet <edumazet@google.com>

BTW, are you planning to patch iproute2 misc/ss soon ?
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