On Tue, 3 May 2022 21:56:48 +0300 Maxim Mikityanskiy wrote:

quoted

quoted

Yes, I agree that if the application opted in, it should work properly
regardless of whether the optimization actually did turn on. However,
the indication could be useful, for example, for diagnostic purposes, to
show the user whether zerocopy mode was enabled, if someone is trying to
debug some performance issue. If you insist, though, I can make
setsockopt succeed and getsockopt return 1. What do you think?  

I'd say "whether the optimization is applicable" rather than "whether
the optimization is turned on". User can check whether the connection
is using SW or HW TLS if they want to make sure it's taken advantage of.

Speaking of which, should we report the state of this knob via socket
diag?  

That sounds like an option, I'll take a look. TLS doesn't expose 
anything via diag yet, does it? The only option to distinguish SW/HW TLS 
is ethtool, and there is no per-socket check, right? Cause a HW TLS 
socket can downgrade to SW after tls_device_down, and ethtool won't show it.

It does - look for tls_get_info()