Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit

[jianhai luan <jianhai.luan@xxxxxxxxxx>]

On 2013-10-15 20:58, Wei Liu wrote:
> On Tue, Oct 15, 2013 at 07:26:31PM +0800, jianhai luan wrote:
> [...]
> > > > > Can you propose a patch?
> > > > Because credit_timeout.expire always after jiffies, i judge the
> > > > value over the range of time_after_eq() by time_before(now,
> > > > vif->credit_timeout.expires). please check the patch.
> > > I don't think this really fix the issue for you. You still have chance
> > > that now wraps around and falls between expires and next_credit. In that
> > > case it's stalled again.
> > if time_before(now, vif->credit_timeout.expires) is true, time wrap
> > and do operation. Otherwise time_before(now,
> > vif->credit_timeout.expires) isn't true, now -
> > vif->credit_timeout.expires should be letter than ULONG_MAX/2.
> > Because next_credit large than vif->credit_timeout.expires
> > (next_crdit = vif->credit_timeout.expires +
> > msecs_to_jiffies(vif->credit_usec/1000)), the delta between now and
> > next_credit should be in range of time_after_eq().  So
> > time_after_eq() do correctly judge.
> Not sure I understand you. Consider "now" is placed like this:
>
>     expires   now   next_credit
>     ----time increases this direction--->
>
> * time_after_eq(now, next_credit) -> false
> * time_before(now, expires) -> false
>
> Then it's stuck again. You're merely narrowing the window, not fixing
> the real problem.
The above environment isn't stack again. The netback will pending one 
timer to process the environment.
The attachment program will prove if !(time_after_eq(now, next_credit) 
|| time_before(now, vif->credit_timeout.expires)), now will only be 
placed in  above environment [ expires next_credit),  and the above 
environment will be processed by timer in soon.
> Wei.
>
> > Jason
> > > Wei.
Jason.

Attachment: main.c
Description: Text document

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