On Tue, May 16, 2017 at 8:44 AM, Miroslav Lichvar [off-list ref] wrote:

If software timestamping is enabled by the SO_TIMESTAMP(NS) option
when a message without timestamp is already waiting in the queue, the
__sock_recv_timestamp() function will read the current time to make a
timestamp in order to always have something for the application.

However, this applies also to outgoing packets looped back to the error
queue when hardware timestamping is enabled by the SO_TIMESTAMPING
option.

This is already the case for sockets that have both software receive
timestamps and hardware tx timestamps enabled, independent from
the new option SOF_TIMESTAMPING_OPT_TX_SWHW, right? If so,
then this behavior must remain.