Re: [PATCH v3 3/8] s390/sclp: rework sclp boundary and length checks

[Christian Borntraeger]

On 19.06.20 12:50, Janosch Frank wrote:
> On 6/19/20 12:22 AM, Collin Walling wrote:
>> Rework the SCLP boundary check to account for different SCLP commands
>> (eventually) allowing different boundary sizes.
>>
>> Move the length check code into a separate function, and introduce a
>> new function to determine the length of the read SCP data (i.e. the size
>> from the start of the struct to where the CPU entries should begin).
>>
>> The format of read CPU info is unlikely to change in the future,
>> so we do not require a separate function to calculate its length.
>>
>> Signed-off-by: Collin Walling <walling@linux.ibm.com>
> 
> Acked-by: Janosch Frank <frankja@linux.ibm.com>
> 
>> ---
> [...]
>> +/*
>> + * The data length denotes the start of the struct to where the first
>> + * CPU entry is to be allocated. This value also denotes the offset_cpu
>> + * field.
>> + */
>> +static inline int get_read_scp_info_data_len(void)
>> +{
>> +    return offsetof(ReadInfo, entries);
>> +}
>> +
>>  /* Provide information about the configuration, CPUs and storage */
>>  static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
>>  {
>> @@ -74,17 +112,16 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
>>      int cpu_count;
>>      int rnsize, rnmax;
>>      IplParameterBlock *ipib = s390_ipl_get_iplb();
>> +    int data_len = get_read_scp_info_data_len();
> 
> Does somebody have a better name than data_len at hand?

I stumbled over the same (also for the function). What about cpu_offset instead 
of data_len?