Re: [PATCH v2 2/3] cxl/region: Factor out interleave ways setup

[Alejandro Lucero Palau <alucerop@amd.com>]

On 2/25/26 23:49, Alison Schofield wrote:
> On Wed, Feb 25, 2026 at 12:22:22PM +0000, alejandro.lucero-palau@amd.com wrote:
>> From: Alejandro Lucero <alucerop@amd.com>
>>
>> Region creation based on Type3 devices can be triggered from user space
>> allowing memory combination through interleaving.
>>
>> In preparation for kernel driven region creation, that is Type2 drivers
>> triggering region creation backed with its advertised CXL memory, factor
>> out a common helper from the user-sysfs region setup for interleave ways.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
>> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
>> Reviewed-by: Gregory Price <gourry@gourry.net>
>> Tested-by: Gregory Price <gourry@gourry.net>
>> ---
>>   drivers/cxl/core/region.c | 41 +++++++++++++++++++++++++--------------
>>   1 file changed, 26 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index cac33c99fe6a..3ef4ccf1c92b 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -485,22 +485,14 @@ static ssize_t interleave_ways_show(struct device *dev,
>>   
>>   static const struct attribute_group *get_cxl_region_target_group(void);
>>   
>> -static ssize_t interleave_ways_store(struct device *dev,
>> -				     struct device_attribute *attr,
>> -				     const char *buf, size_t len)
>> +static int set_interleave_ways(struct cxl_region *cxlr, int val)
>>   {
>> -	struct cxl_region *cxlr = to_cxl_region(dev);
>>   	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
>>   	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
>>   	struct cxl_region_params *p = &cxlr->params;
>> -	unsigned int val, save;
>> -	int rc;
>> +	int save, rc;
>>   	u8 iw;
> Why the type differences? set_interleave_ways() takes an int while
> the sysfs store path parses val as unsigned int via kstrtouint()?
> How about keeping the helper argument type aligned with the sysfs
> parse type (and/or p->interleave_ways type)?


Yes, that was pointed out for interleave_granularity_store by Ben 
Cheatham, and I did change there from kstrtouint to kstrtoint as 
cxl_regions_params expect int type.

I forgot to do the same here.


>
> Even if todays sysfs path won't pass negative, the helper is
> being positioned for non sysfs callers IIUC.


Not sure what you mean here. Should I do the change above as with 
granularity?


>
> Similar question with 'save'? Should it match type of
> p->interleave_ways?


save is an int and interleave_ways as defined in cxl_region_params is an 
int.


Thank you


>
>
>>   
>> -	rc = kstrtouint(buf, 0, &val);
>> -	if (rc)
>> -		return rc;
>> -
>>   	rc = ways_to_eiw(val, &iw);
>>   	if (rc)
>>   		return rc;
>> @@ -515,9 +507,7 @@ static ssize_t interleave_ways_store(struct device *dev,
>>   		return -EINVAL;
>>   	}
>>   
>> -	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
>> -	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
>> -		return rc;
>> +	lockdep_assert_held_write(&cxl_rwsem.region);
>>   
>>   	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE)
>>   		return -EBUSY;
>> @@ -525,10 +515,31 @@ static ssize_t interleave_ways_store(struct device *dev,
>>   	save = p->interleave_ways;
>>   	p->interleave_ways = val;
>>   	rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
>> -	if (rc) {
>> +	if (rc)
>>   		p->interleave_ways = save;
>> +
>> +	return rc;
>> +}
>> +
>> +static ssize_t interleave_ways_store(struct device *dev,
>> +				     struct device_attribute *attr,
>> +				     const char *buf, size_t len)
>> +{
>> +	struct cxl_region *cxlr = to_cxl_region(dev);
>> +	unsigned int val;
>> +	int rc;
>> +
>> +	rc = kstrtouint(buf, 0, &val);
>> +	if (rc)
>> +		return rc;
>> +
>> +	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
>> +	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
>> +		return rc;
>> +
>> +	rc = set_interleave_ways(cxlr, val);
>> +	if (rc)
>>   		return rc;
>> -	}
>>   
>>   	return len;
>>   }
>> -- 
>> 2.34.1
>>
>>