We currently use a special structure (struct skb_timeval) and plain 'struct 
timeval' to store packet timestamps in sk_buffs and struct sock.

This has some drawbacks :
- Fixed resolution of micro second.
- Waste of space on 64bit platforms where sizeof(struct timeval)=16

I suggest using ktime_t that is a nice abstraction of high resolution time 
services, currently capable of nanosecond resolution.

As sizeof(ktime_t) is 8 bytes, using ktime_t in 'struct sock' permits a 8 byte 
shrink of this structure on 64bit architectures. Some other structures also 
benefit from this size reduction (struct ipq in ipv4/ip_fragment.c, struct 
frag_queue in ipv6/reassembly.c, ...)


Once this ktime infrastructure adopted, we can more easily provide nanosecond 
resolution on top of it. (ioctl SIOCGSTAMPNS and/or 
SO_TIMESTAMPNS/SCM_TIMESTAMPNS)

Note : this patch includes a bug correction in compat_sock_get_timestamp() 
where a "err = 0;" was missing (so this syscall returned -ENOENT instead of 
0)

Signed-off-by: Eric Dumazet <redacted>
CC: Stephen Hemminger <redacted>
CC: John find <redacted>

 include/linux/skbuff.h                  |   26 ++++------------------
 include/net/sock.h                      |   18 +++++++--------
 net/bridge/netfilter/ebt_ulog.c         |    6 +++--
 net/compat.c                            |   15 ++++++++----
 net/core/dev.c                          |   19 +++-------------
 net/core/sock.c                         |   16 +++++++------
 net/econet/af_econet.c                  |    2 -
 net/ipv4/ip_fragment.c                  |    6 ++---
 net/ipv4/netfilter/ip_queue.c           |    6 +++--
 net/ipv4/netfilter/ipt_ULOG.c           |    8 ++++--
 net/ipv6/exthdrs.c                      |    2 -
 net/ipv6/netfilter/ip6_queue.c          |    6 +++--
 net/ipv6/netfilter/nf_conntrack_reasm.c |    6 ++---
 net/ipv6/reassembly.c                   |    6 ++---
 net/ipx/af_ipx.c                        |    4 +--
 net/netfilter/nfnetlink_log.c           |    8 +++---
 net/netfilter/nfnetlink_queue.c         |    8 +++---
 net/packet/af_packet.c                  |    8 ++++--
 18 files changed, 80 insertions(+), 90 deletions(-)