[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, 3 deletions

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 7034c54..1dde449 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -88,7 +88,7 @@ struct frag_queue
 	int			len;
 	int			meat;
 	int			iif;
-	struct timeval		stamp;
+	ktime_t			stamp;
 	unsigned int		csum;
 	__u8			last_in;	/* has first/last segment arrived? */
 #define COMPLETE		4
@@ -562,7 +562,7 @@ static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 	if (skb->dev)
 		fq->iif = skb->dev->ifindex;
 	skb->dev = NULL;
-	skb_get_timestamp(skb, &fq->stamp);
+	fq->stamp = skb->tstamp;
 	fq->meat += skb->len;
 	atomic_add(skb->truesize, &ip6_frag_mem);
 
@@ -663,7 +663,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
 
 	head->next = NULL;
 	head->dev = dev;
-	skb_set_timestamp(head, &fq->stamp);
+	head->tstamp = fq->stamp;
 	head->nh.ipv6h->payload_len = htons(payload_len);
 	IP6CB(head)->nhoff = nhoff;