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[NET]: convert network timestamps to ktime_t

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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>
This commit is contained in:
Eric Dumazet 2007-04-19 16:16:32 -07:00 • committed by David S. Miller
parent 3927f2e8f9
commit b7aa0bf70c
20 changed files with 85 additions and 98 deletions
Download patch file Download diff file Expand all files Collapse all files

15
net/compat.c
View file

@ -545,15 +545,20 @@ int compat_sock_get_timestamp(struct sock *sk, struct timeval __user *userstamp)
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;
}