Re: [Qemu-devel] [RFC PATCH v1 4/5] pc-bios/s390-ccw: Break up virtio-scsi read into multiples

[Eric Farman <farman@linux.vnet.ibm.com>]

On 04/26/2017 11:17 AM, Eric Blake wrote:
> On 04/26/2017 09:46 AM, Eric Farman wrote:
>> A virtio-scsi request that goes through the host sd driver and
>> exceeds the maximum transfer size is automatically broken up
>> for us. But the equivalent request going to the sg driver
>> presumes that any length requirements have already been honored.
>> Let's use the max_sectors field from the device and break up
>> all virtio-scsi requests (both sd and sg) to avoid problem from
>> the host drivers.
>>
>> Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
>> ---
>>  pc-bios/s390-ccw/s390-ccw.h    |  4 ++++
>>  pc-bios/s390-ccw/virtio-scsi.c | 19 ++++++++++++++-----
>>  2 files changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
>> index ded67bc..e1f3751 100644
>> --- a/pc-bios/s390-ccw/s390-ccw.h
>> +++ b/pc-bios/s390-ccw/s390-ccw.h
>> @@ -42,6 +42,10 @@ typedef unsigned long long __u64;
>>  #ifndef NULL
>>  #define NULL    0
>>  #endif
>> +#ifndef MIN
>> +#define MIN(a, b) (((a) < (b)) ? (a) : (b));
>> +#endif
>
> osdep.h defines MIN() for ALL files, so this hunk is spurious.

Ah, so it does.  Okay, removed.  Thanks!

I guess it would make sense for the hunk that uses it to use 
MIN_NON_ZERO instead, which is also defined there.

>