[NET]: convert network timestamps to ktime_t

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 <dada1@cosmosbay.com>
CC: Stephen Hemminger <shemminger@linux-foundation.org>
CC: John find <linux.kernel@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 7 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 2772fee93881..22f61aee4824 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -798,16 +798,12 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
                 dprintk("svc: recvfrom returned error %d\n", -err);
         }
         rqstp->rq_addrlen = sizeof(rqstp->rq_addr);
-        if (skb->tstamp.off_sec == 0) {
-                struct timeval tv;
-
-                tv.tv_sec = xtime.tv_sec;
-                tv.tv_usec = xtime.tv_nsec / NSEC_PER_USEC;
-                skb_set_timestamp(skb, &tv);
+        if (skb->tstamp.tv64 == 0) {
+                skb->tstamp = ktime_get_real();
                 /* Don't enable netstamp, sunrpc doesn't
                    need that much accuracy */
         }
-        skb_get_timestamp(skb, &svsk->sk_sk->sk_stamp);
+        svsk->sk_sk->sk_stamp = skb->tstamp;
         set_bit(SK_DATA, &svsk->sk_flags); /* there may be more data... */
 
         /*