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On 7/4/25 10:53 AM, chia-yu.chang@nokia-bell-labs.com wrote:
@@ -285,9 +297,33 @@ static inline void tcp_ecn_received_counters(struct sock *sk,
if (len > 0) { u8 minlen =tcp_ecnfield_to_accecn_optfield(ecnfield);
u32 oldbytes = tp->received_ecn_bytes[ecnfield -- 1];
tp->received_ecn_bytes[ecnfield - 1] += len; tp->accecn_minlen = max_t(u8, tp->accecn_minlen, minlen);/* Demand AccECN option at least every 2^22 bytes to* avoid overflowing the ECN byte counters.*/if ((tp->received_ecn_bytes[ecnfield - 1] ^ oldbytes) &~((1 << 22) - 1)) {I don't understand the above statement, I don't think it yield the result expected according to the above comment.
Hi Paolo,
I was thinking to change it into GENMASK_U32() and comments like below.
It is intended to send AccECN option at least once per 2^22-byte increase in the counter.
But this is done by checking the bit edges (from bit 22) of the byte counters to avoid extra variables.
u32 oldbytes = tp->received_ecn_bytes[ecnfield - 1]; u32 bytes_mask = GENMASK_U32(31, 22);
tp->received_ecn_bytes[ecnfield - 1] += len; tp->accecn_minlen = max_t(u8, tp->accecn_minlen, minlen);
/* Send AccECN option if any ECN byte counter is * increased by at least 2^22 bytes. */ if ((tp->received_ecn_bytes[ecnfield - 1] ^ oldbytes) & bytes_mask) { tcp_accecn_opt_demand_min(sk, 1); }
Would it make more sense to you?