[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>
diff --git a/net/compat.c b/net/compat.c
index 1f32866..17c2710 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -545,15 +545,20 @@
struct compat_timeval __user *ctv =
(struct compat_timeval __user*) userstamp;
int err = -ENOENT;
+ struct timeval tv;
if (!sock_flag(sk, SOCK_TIMESTAMP))
sock_enable_timestamp(sk);
- if (sk->sk_stamp.tv_sec == -1)
+ tv = ktime_to_timeval(sk->sk_stamp);
+ if (tv.tv_sec == -1)
return err;
- if (sk->sk_stamp.tv_sec == 0)
- do_gettimeofday(&sk->sk_stamp);
- if (put_user(sk->sk_stamp.tv_sec, &ctv->tv_sec) ||
- put_user(sk->sk_stamp.tv_usec, &ctv->tv_usec))
+ if (tv.tv_sec == 0) {
+ sk->sk_stamp = ktime_get_real();
+ tv = ktime_to_timeval(sk->sk_stamp);
+ }
+ err = 0;
+ if (put_user(tv.tv_sec, &ctv->tv_sec) ||
+ put_user(tv.tv_usec, &ctv->tv_usec))
err = -EFAULT;
return err;
}