[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, 4 insertions, 4 deletions

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index b6f055380373..e10be7d7752d 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -92,7 +92,7 @@ struct ipq {
         spinlock_t      lock;
         atomic_t        refcnt;
         struct timer_list timer;        /* when will this queue expire?         */
-        struct timeval  stamp;
+        ktime_t         stamp;
         int             iif;
         unsigned int    rid;
         struct inet_peer *peer;
@@ -592,7 +592,7 @@ static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
         if (skb->dev)
                 qp->iif = skb->dev->ifindex;
         skb->dev = NULL;
-        skb_get_timestamp(skb, &qp->stamp);
+        qp->stamp = skb->tstamp;
         qp->meat += skb->len;
         atomic_add(skb->truesize, &ip_frag_mem);
         if (offset == 0)
@@ -674,7 +674,7 @@ static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev)
 
         head->next = NULL;
         head->dev = dev;
-        skb_set_timestamp(head, &qp->stamp);
+        head->tstamp = qp->stamp;
 
         iph = head->nh.iph;
         iph->frag_off = 0;
@@ -734,7 +734,7 @@ struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user)
         return NULL;
 }
 
-void ipfrag_init(void)
+void __init ipfrag_init(void)
 {
         ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
                                  (jiffies ^ (jiffies >> 6)));