Re: [PATCH 5.10 099/167] tcp: disable TFO blackhole logic by default

Hi!

[ Upstream commit 213ad73d06073b197a02476db3a4998e219ddb06 ]

Multiple complaints have been raised from the TFO users on the internet stating that the TFO blackhole logic is too aggressive and gets falsely triggered too often. (e.g. https://blog.apnic.net/2021/07/05/tcp-fast-open-not-so-fast/) Considering that most middleboxes no longer drop TFO packets, we decide to disable the blackhole logic by setting /proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_set to 0 by default.

I understand this makes sense for mainline, but should we have this in stable? Somebody may still be using broken middlebox with their "stable" server.

Best regards, Pavel