Re: [PATCH for-5.2 3/6] pc-bios/s390-ccw: Move the inner logic of find_subch() to a separate function

[Thomas Huth <thuth@redhat.com>]

On 29/07/2020 10.54, Cornelia Huck wrote:
> On Tue, 28 Jul 2020 20:37:31 +0200
> Thomas Huth <thuth@redhat.com> wrote:
> 
>> Move the code to a separate function to be able to re-use it from a
>> different spot later.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  pc-bios/s390-ccw/main.c | 99 ++++++++++++++++++++++++-----------------
>>  1 file changed, 57 insertions(+), 42 deletions(-)
>>
>> diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
>> index 9b64eb0c24..9477313188 100644
>> --- a/pc-bios/s390-ccw/main.c
>> +++ b/pc-bios/s390-ccw/main.c
>> @@ -51,6 +51,60 @@ unsigned int get_loadparm_index(void)
>>      return atoui(loadparm_str);
>>  }
>>  
>> +static int check_sch_no(int dev_no, int sch_no)
> 
> check_subchannel()? You verify dev_no as well, if supplied.

Ok.

>> +{
>> +    bool is_virtio;
>> +    Schib schib;
>> +    int r;
>> +
>> +    blk_schid.sch_no = sch_no;
>> +    r = stsch_err(blk_schid, &schib);
>> +    if (r == 3 || r == -EIO) {
>> +        return -EIO;
> 
> -ENODEV? It means that you either have no devices, or an invalid
> subchannel set.

We don't have ENODEV in the s390-ccw bios... but I could introduce it, I
guess :-)

>> +    }
>> +    if (!schib.pmcw.dnv) {
>> +        return false;
>> +    }
>> +
>> +    enable_subchannel(blk_schid);
>> +    cutype = cu_type(blk_schid);
>> +
>> +    /*
>> +     * Note: we always have to run virtio_is_supported() here to make
>> +     * sure that the vdev.senseid data gets pre-initialized correctly
>> +     */
>> +    is_virtio = virtio_is_supported(blk_schid);
>> +
>> +    /* No specific devno given, just return 1st possibly bootable device */
> 
> "just return whether the device is possibly bootable" ?

That makes more sense now, indeed.

>> +    if (dev_no < 0) {
>> +        switch (cutype) {
>> +        case CU_TYPE_VIRTIO:
>> +            if (is_virtio) {
>> +                /*
>> +                 * Skip net devices since no IPLB is created and therefore
>> +                 * no network bootloader has been loaded
>> +                 */
>> +                if (virtio_get_device_type() != VIRTIO_ID_NET) {
>> +                    return true;
>> +                }
>> +            }
>> +            return false;
>> +        case CU_TYPE_DASD_3990:
>> +        case CU_TYPE_DASD_2107:
>> +            return true;
>> +        default:
>> +            return false;
>> +        }
>> +    }
>> +
>> +    /* Caller asked for a specific devno */
>> +    if (schib.pmcw.dev == dev_no) {
>> +        return true;
>> +    }
>> +
>> +    return false;
>> +}
>> +
>>  /*
>>   * Find the subchannel connected to the given device (dev_no) and fill in the
>>   * subchannel information block (schib) with the connected subchannel's info.
>  (...)
> 
> Otherwise, LGTM.

Thanks!

 Thomas