net: new user space API for time stamping of incoming and outgoing packets

User space can request hardware and/or software time stamping.
Reporting of the result(s) via a new control message is enabled
separately for each field in the message because some of the
fields may require additional computation and thus cause overhead.
User space can tell the different kinds of time stamps apart
and choose what suits its needs.

When a TX timestamp operation is requested, the TX skb will be cloned
and the clone will be time stamped (in hardware or software) and added
to the socket error queue of the skb, if the skb has a socket
associated with it.

The actual TX timestamp will reach userspace as a RX timestamp on the
cloned packet. If timestamping is requested and no timestamping is
done in the device driver (potentially this may use hardware
timestamping), it will be done in software after the device's
start_hard_xmit routine.

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/sockios.h b/include/linux/sockios.h
index abef7596655a..241f179347d9 100644
--- a/include/linux/sockios.h
+++ b/include/linux/sockios.h
@@ -122,6 +122,9 @@
 #define SIOCBRADDIF     0x89a2          /* add interface to bridge      */
 #define SIOCBRDELIF     0x89a3          /* remove interface from bridge */
 
+/* hardware time stamping: parameters in linux/net_tstamp.h */
+#define SIOCSHWTSTAMP   0x89b0
+
 /* Device private ioctl calls */
 
 /*