On Mon, Jul 27, 2020 at 03:15:05PM +0300, Ido Schimmel wrote:

I see a regression with IPv6 flowlabel that I bisected to this patch.
When passing '-F 0' to 'ping' the flow label should be random, yet it's
the same every time after this patch.

Can you send a reproducer?

It seems that the pointer is never advanced after the call to
sockptr_advance() because it is passed by value and not by reference.
Even if you were to pass it by reference I think you would later need to
call sockptr_decrease() or something similar. Otherwise it is very
error-prone.

Maybe adding an offset to copy_to_sockptr() and copy_from_sockptr() is
better?

We could do that, although I wouldn't add it to the existing functions
to avoid the churns and instead add copy_to_sockptr_offset or something
like that.