Re: [PATCH] net/tls: Fix return values for setsockopt

On Tue, Dec 3, 2019 at 6:08 PM Jakub Kicinski
[off-list ref] wrote:

On Tue,  3 Dec 2019 23:44:58 +0100, Valentin Vidic wrote:

quoted

ENOTSUPP is not available in userspace:

  setsockopt failed, 524, Unknown error 524

Signed-off-by: Valentin Vidic <redacted>

I'm not 100% clear on whether we can change the return codes after they
had been exposed to user space for numerous releases..

This has also come up in the context of SO_ZEROCOPY in the past. In my
opinion the answer is no. A quick grep | wc -l in net/ shows 99
matches for this error code. Only a fraction of those probably make it
to userspace, but definitely more than this single case.

If anything, it may be time to define it in uapi?

But if we can - please fix the tools/testing/selftests/net/tls.c test
as well, because it expects ENOTSUPP.

Even if changing the error code, EOPNOTSUPP is arguably a better
replacement. The request itself is valid. Also considering forward
compatibility.