Re: [PATCH 2/2] drivers/vfio: Support EEH error injection

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Thu, Mar 12, 2015 at 11:57:21AM +1100, David Gibson wrote:
>On Wed, Mar 11, 2015 at 05:34:11PM +1100, Gavin Shan wrote:
>> The patch adds one more EEH sub-command (VFIO_EEH_PE_INJECT_ERR)
>> to inject the specified EEH error, which is represented by
>> (struct vfio_eeh_pe_err), to the indicated PE for testing purpose.
>> 
>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> ---
>>  Documentation/vfio.txt        | 47 ++++++++++++++++++++++++++++++-------------
>>  drivers/vfio/vfio_spapr_eeh.c | 14 +++++++++++++
>>  include/uapi/linux/vfio.h     | 34 ++++++++++++++++++++++++++++++-
>>  3 files changed, 80 insertions(+), 15 deletions(-)
>> 
>> diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
>> index 96978ec..2e7f736 100644
>> --- a/Documentation/vfio.txt
>> +++ b/Documentation/vfio.txt
>> @@ -328,7 +328,13 @@ So 4 additional ioctls have been added:
>>  
>>  The code flow from the example above should be slightly changed:
>>  
>> -	struct vfio_eeh_pe_op pe_op = { .argsz = sizeof(pe_op), .flags = 0 };
>> +	struct vfio_eeh_pe_op *pe_op;
>> +	struct vfio_eeh_pe_err *pe_err;
>> +
>> +	pe_op = malloc(sizeof(*pe_op) + sizeof(*pe_err));
>> +	pe_err = (void *)pe_op + sizeof(*pe_op);
>> +	pe_op->argsz = sizeof(*pe_op) + sizeof(*pe_err);
>
>Surely that argsz can't be correct for most of the operations.  The
>extended structure should only be there for the error inject ioctl,
>yes?
>

argsz isn't appropriate for most cases because kernel has the check
"expected_argsz < passed_argsz", not "expected_argsz == passed_argsz".
However, I'll fix it as follows to avoid confusion after collecting
more comments:

	struct vfio_eeh_pe_op *pe_op;
	struct vfio_eeh_pe_err *pe_err;

	/* For all cases except error injection */
	pe_op = malloc(sizeof(*pe_op));
	pe_op->argsz = sizeof(*pe_op);

	/* For error injection case here */
	pe_op = realloc(sizeof(*pe_op) + sizeof(*pe_err));
	pe_op->argsz = sizeof(*pe_op) + sizeof(*pe_err);
	pe_err = (void *)pe_op + sizeof(*pe_op);

Thanks,
Gavin

>-- 
>David Gibson			| I'll have my music baroque, and my code
>david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
>				| _way_ _around_!
>http://www.ozlabs.org/~dgibson