Re: [Xen-devel] [PATCH RFC v2 03/12] xen/mem_event: Relax error condition on debug builds

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.08.14 at 19:02, <andres@xxxxxxxxxxxxxxxx> wrote:
> On Wed, Aug 27, 2014 at 7:06 AM, Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>
> wrote:
> 
>> A faulty tool stack can brick a debug hypervisor. Unpleasant while
>> dev/test.
>>
>> Suggested-by: Andres Lagar Cavilla <andres@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>
>> ---
>>  xen/common/mem_event.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/common/mem_event.c b/xen/common/mem_event.c
>> index e22b78e..8be32e1 100644
>> --- a/xen/common/mem_event.c
>> +++ b/xen/common/mem_event.c
>> @@ -279,7 +279,11 @@ void mem_event_put_request(struct domain *d,
>>      if ( current->domain != d )
>>      {
>>          req->flags |= MEM_EVENT_FLAG_FOREIGN;
>> -        ASSERT( !(req->flags & MEM_EVENT_FLAG_VCPU_PAUSED) );
>> +#ifndef NDEBUG
>> +        if ( !(req->flags & MEM_EVENT_FLAG_VCPU_PAUSED) )
>> +            printk(XENLOG_G_WARNING
>> +                   "VCPU was not paused.\n");
>>
> 
> 1. use gdprintk

Maybe, but then the message (which now will include current
domain/vcpu) should also include subject domain and vcpu; perhaps
it should have done so from the beginning to make it half way useful.

> 2. enclose only the gdprintk in #ifdef
> 3. if the flags contain the improper VCPU_PAUSED value, also clear that
> value from flags (regardless from NDEBUG)

How would fixing (actually setting rather than clearing) that flag
help (as this wouldn't put the vcpu in the intended state)?

Jan


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