Re: [PATCH v2 07/20] s390/zcrypt: Rework zcrypt function zcrypt_device_status_mask_ext

[Harald Freudenberger <freude@linux.ibm.com>]

On 2025-03-19 12:03, Holger Dengler wrote:
> On 04/03/2025 18:21, Harald Freudenberger wrote:
>> Rework the existing function zcrypt_device_status_mask_ext():
>> * Add two new parameters to provide upper limits for
>>   cards and queues. The existing implementation needed an
>>   array of 256 * 256 * 4 = 256 KB which is really huge. The
>>   reworked function is more flexible in the sense that the
>>   caller can decide the upper limit for cards and domains to
>>   be stored into the status array. So for example a caller may
>>   decide to only query for cards 0...127 and queues 0...127
>>   and thus only an array of size 128 * 128 * 4 = 64 KB is needed.
>> * Instead of void the reworked function now returns an int.
>>   The currently only way to have the function return != 0
>>   is by providing card or domains limits beyond 256.
> 
> I would prefer to stay with a void function and limit the card and
> domain values to the current maximum. Details below.
> 
>> 
>> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
>> ---
>>  drivers/s390/crypto/zcrypt_api.c      | 20 +++++++++++++++-----
>>  drivers/s390/crypto/zcrypt_api.h      |  3 ++-
>>  drivers/s390/crypto/zcrypt_ccamisc.c  | 22 +++++++++++++++++-----
>>  drivers/s390/crypto/zcrypt_ep11misc.c | 14 ++++++++++----
>>  4 files changed, 44 insertions(+), 15 deletions(-)
>> 
>> diff --git a/drivers/s390/crypto/zcrypt_api.c 
>> b/drivers/s390/crypto/zcrypt_api.c
>> index 62cc05881b13..bd2738e3792a 100644
>> --- a/drivers/s390/crypto/zcrypt_api.c
>> +++ b/drivers/s390/crypto/zcrypt_api.c
>> @@ -1317,19 +1317,25 @@ static void zcrypt_device_status_mask(struct 
>> zcrypt_device_status *devstatus)
>>  	spin_unlock(&zcrypt_list_lock);
>>  }
>> 
>> -void zcrypt_device_status_mask_ext(struct zcrypt_device_status_ext 
>> *devstatus)
>> +int zcrypt_device_status_mask_ext(struct zcrypt_device_status_ext 
>> *devstatus,
>> +				  int maxcard, int maxqueue)
> 
> Keep void and ...
> 
>>  {
>>  	struct zcrypt_card *zc;
>>  	struct zcrypt_queue *zq;
>>  	struct zcrypt_device_status_ext *stat;
>>  	int card, queue;
>> 
>> +	if (maxcard > MAX_ZDEV_CARDIDS_EXT || maxqueue > 
>> MAX_ZDEV_DOMAINS_EXT)
>> +		return -EINVAL;
>> +
> 
> ... limit maxcard/maxqueue to the maximum supported values. In my
> opinion, it does not make any sense to call this function with higher
> values than the maximum.
> 
> maxcard = MIN(maxcard, MAX_ZDEV_CARDIDS_EXT);
> maxqueue = MIN(maxqueue, MAX_ZDEV_DOMAINS_EXT);
> 
> As a side effect, it keeps the caller code much simpler.
> 
>>  	spin_lock(&zcrypt_list_lock);
>>  	for_each_zcrypt_card(zc) {
>>  		for_each_zcrypt_queue(zq, zc) {
>>  			card = AP_QID_CARD(zq->queue->qid);
>>  			queue = AP_QID_QUEUE(zq->queue->qid);
>> -			stat = &devstatus[card * AP_DOMAINS + queue];
>> +			if (card >= maxcard || queue >= maxqueue)
>> +				continue;
>> +			stat = &devstatus[card * maxqueue + queue];
>>  			stat->hwtype = zc->card->ap_dev.device_type;
>>  			stat->functions = zc->card->hwinfo.fac >> 26;
>>  			stat->qid = zq->queue->qid;
> [...]
>> @@ -1635,9 +1643,11 @@ static long zcrypt_unlocked_ioctl(struct file 
>> *filp, unsigned int cmd,
>>  					 GFP_KERNEL);
>>  		if (!device_status)
>>  			return -ENOMEM;
>> -		zcrypt_device_status_mask_ext(device_status);
>> -		if (copy_to_user((char __user *)arg, device_status,
>> -				 total_size))
>> +		rc = zcrypt_device_status_mask_ext(device_status,
>> +						   MAX_ZDEV_CARDIDS_EXT,
>> +						   MAX_ZDEV_DOMAINS_EXT);
>> +		if (!rc && copy_to_user((char __user *)arg, device_status,
>> +					total_size))
> 
> With the change above, you can stay with the current error handling.
> Only the addition parameters for zcrypt_device_status_mask_ext() need
> to be added.
> 
>>  			rc = -EFAULT;
>>  		kvfree(device_status);
>>  		return rc;
> [...]

Done as suggested - only I used typed min (min_t()) instead of MIN.
-> v3