Re: [Xen-devel] [PATCH net] xen-netback: add the scenario which now beyond the range time_after_eq().

["David Laight" <David.Laight@xxxxxxxxxx>]

> > My understanding is this patch does not simply double the span, it is
> > just stricter than the original one. Please check my previous comments,
> > I paste it here.
> 
> No, the code (on a 32-bit arch) just _can't_ handle jiffies differences
> beyond 2^32, no matter how cleverly you use the respective macros.
> All arithmetic there is done modulo 2^32.

I haven't followed this discussion very closely but it might be possible
to arrange that the 'incorrect lack of credit' only occurs for a few
seconds every time 'jiffies' wraps - instead of half of the time.
Then you'd have to be extremely unlucky to hit the timing window.

        David




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