Re: [RFC v1 1/4] vfio-ccw: Set orb.cmd.c64 before calling ccwchain_handle_ccw

[Farhan Ali <alifm@linux.ibm.com>]

On 07/02/2019 04:26 AM, Cornelia Huck wrote:
> On Mon,  1 Jul 2019 12:23:43 -0400
> Farhan Ali <alifm@linux.ibm.com> wrote:
> 
>> Because ccwchain_handle_ccw calls ccwchain_calc_length and
>> as per the comment we should set orb.cmd.c64 before calling
>> ccwchanin_calc_length.
>>
>> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
>> ---
>>   drivers/s390/cio/vfio_ccw_cp.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
>> index d6a8dff..5ac4c1e 100644
>> --- a/drivers/s390/cio/vfio_ccw_cp.c
>> +++ b/drivers/s390/cio/vfio_ccw_cp.c
>> @@ -640,16 +640,16 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
>>   	memcpy(&cp->orb, orb, sizeof(*orb));
>>   	cp->mdev = mdev;
>>   
>> -	/* Build a ccwchain for the first CCW segment */
>> -	ret = ccwchain_handle_ccw(orb->cmd.cpa, cp);
>> -	if (ret)
>> -		cp_free(cp);
>> -
>>   	/* It is safe to force: if not set but idals used
>>   	 * ccwchain_calc_length returns an error.
>>   	 */
>>   	cp->orb.cmd.c64 = 1;
>>   
>> +	/* Build a ccwchain for the first CCW segment */
>> +	ret = ccwchain_handle_ccw(orb->cmd.cpa, cp);
>> +	if (ret)
>> +		cp_free(cp);
>> +
>>   	if (!ret)
>>   		cp->initialized = true;
>>   
> 
> Hm... has this ever been correct, or did this break only with the
> recent refactorings?
> 
> (IOW, what should Fixes: point to?)
> 
> 

I think it was correct before some of the new refactoring we did. But we 
do need to set before calling ccwchain_calc_length, because the function 
does have a check for orb.cmd.64. I will see which exact commit did it.

Thanks
Farhan