Re: [Xen-devel] [PATCH RFC 04/25] Replace "/" operand with div64

[Keir Fraser <keir.xen@xxxxxxxxx>]

Also, I assume the gcc arm target can at least do 64-bit arithmetic via
library calls, which you could then implement in arch/arm. __divdi3 etc.
Perhaps you intend to do this anyway and do_div() here is a bandaid.

 -- Keir

On 07/12/2011 07:00, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> wrote:

> Hi, Stefano 
> Great work from you guys!  One quick comment:  Just found the below logic's
> change maybe wrong and probably  break current things.
> Original logic is  A+B -(C%D), but it is changed to  (A+B-C)%D,  so if it is
> not an intended fix, it should be an issue.
> Thanks!
> Xiantao  
> 
>> diff --git a/xen/common/timer.c b/xen/common/timer.c index 0547ea3..043250e
>> 100644
>> --- a/xen/common/timer.c
>> +++ b/xen/common/timer.c
>> @@ -23,6 +23,7 @@
>> #include <xen/symbols.h>
>> #include <asm/system.h>
>> #include <asm/desc.h>
>> +#include <asm/div64.h>
>> #include <asm/atomic.h>
>> 
>> /* We program the time hardware this far behind the closest deadline. */ @@
>> -503,16 +504,18 @@ static void timer_softirq_action(void)
>> 
>> s_time_t align_timer(s_time_t firsttick, uint64_t period)  {
>> +    uint64_t n;
>>    if ( !period )
>>        return firsttick;
>  
>> -    return firsttick + (period - 1) - ((firsttick - 1) % period);
>> +    n = firsttick + (period - 1) - (firsttick - 1);
>> +    return do_div(n, period);
>> }
>  
> 
> 
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