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[NET]: Fix packet timestamping.

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I've found the problem in general.  It affects any 64-bit
architecture.  The problem occurs when you change the system time.

Suppose that when you boot your system clock is forward by a day.
This gets recorded down in skb_tv_base.  You then wind the clock back
by a day.  From that point onwards the offset will be negative which
essentially overflows the 32-bit variables they're stored in.

In fact, why don't we just store the real time stamp in those 32-bit
variables? After all, we're not going to overflow for quite a while
yet.

When we do overflow, we'll need a better solution of course.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu
2005-10-03 13:57:23 -07:00
committed by David S. Miller
parent ddea7be0ec
commit 325ed82393
8 changed files with 15 additions and 26 deletions
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5
net/core/skbuff.c
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@ -71,8 +71,6 @@
static kmem_cache_t *skbuff_head_cache __read_mostly;
static kmem_cache_t *skbuff_fclone_cache __read_mostly;
struct timeval __read_mostly skb_tv_base;
/*
* Keep out-of-line to prevent kernel bloat.
* __builtin_return_address is not used because it is not always
@ -1708,8 +1706,6 @@ void __init skb_init(void)
NULL, NULL);
if (!skbuff_fclone_cache)
panic("cannot create skbuff cache");
do_gettimeofday(&skb_tv_base);
}
EXPORT_SYMBOL(___pskb_trim);
@ -1743,4 +1739,3 @@ EXPORT_SYMBOL(skb_prepare_seq_read);
EXPORT_SYMBOL(skb_seq_read);
EXPORT_SYMBOL(skb_abort_seq_read);
EXPORT_SYMBOL(skb_find_text);
EXPORT_SYMBOL(skb_tv_base);