From b7aa0bf70c4afb9e38be25f5c0922498d0f8684c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 19 Apr 2007 16:16:32 -0700 Subject: [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 CC: Stephen Hemminger CC: John find Signed-off-by: David S. Miller --- net/compat.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'net/compat.c') diff --git a/net/compat.c b/net/compat.c index 1f32866d09b..17c2710b2b9 100644 --- a/net/compat.c +++ b/net/compat.c @@ -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; } -- cgit v1.2.3-18-g5258