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

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.



Attachment: main.c
Description: Text document

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