tcp: remove superfluous checks for ECN session
AbandonedPublic
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Authored by rscheff on Jan 3 2024, 10:22 PM.

Details

Reviewers

cc
tuexen
rrs

Group Reviewers

transport

Summary

When a congestion control reaction is triggered, and the session
is in RFC3168 ECN mode, eventually a CWR should be sent. However,
sending of the TCP Flag is also gated on the same condition - so
it is not needed to validate before setting the internal tracking
flag.

No external functional change.

Diff Detail

Repository

rG FreeBSD src repository

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Lint Passed

Unit

No Test Coverage

Build Status

Buildable 55226
Build 52115: arc lint + arc unit

Event Timeline

rscheff created this revision.Jan 3 2024, 10:22 PM

Herald added a reviewer: transport. · View Herald TranscriptJan 3 2024, 10:22 PM

Herald added subscribers: glebius, melifaro, imp. · View Herald Transcript

rscheff requested review of this revision.Jan 3 2024, 10:22 PM

Harbormaster completed remote builds in B55226: Diff 132235.Jan 3 2024, 10:22 PM

rrs added inline comments.Mar 31 2024, 12:05 PM

sys/netinet/tcp_stacks/rack.c
5926	The only thing I find a bit strange about this change is that this now means if ECN is not negotiated, and there is any type of loss the tflags2 is going to carry with it forever TF2_ECN_SND_CWR... which should be noted in a comment somewhere for some future person debugging the stacks...

Discussed in todays transport call, since this is not in the hot path of every packet, and the retention of the internal bit might confuse someone later, it was decided to abandon this change.