Re: [PATCH 5/6] dax/hmem: Reintroduce Soft Reserved ranges back into the iomem tree

["Koralahalli Channabasappa, Smita" <skoralah@amd.com>]

Hi Jonathan,

On 9/10/2025 6:41 AM, Jonathan Cameron wrote:
> On Fri, 22 Aug 2025 03:42:01 +0000
> Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> wrote:
> 
>> Reworked from a patch by Alison Schofield <alison.schofield@intel.com>
>>
>> Reintroduce Soft Reserved range into the iomem_resource tree for dax_hmem
>> to consume.
>>
>> This restores visibility in /proc/iomem for ranges actively in use, while
>> avoiding the early-boot conflicts that occurred when Soft Reserved was
>> published into iomem before CXL window and region discovery.
>>
>> Link: https://lore.kernel.org/linux-cxl/29312c0765224ae76862d59a17748c8188fb95f1.1692638817.git.alison.schofield@intel.com/
>> Co-developed-by: Alison Schofield <alison.schofield@intel.com>
>> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
>> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
> A few trivial things inline. Not are important enough to need a change though.
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> 
>> ---
>>   drivers/dax/hmem/hmem.c | 38 ++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 38 insertions(+)
>>
>> diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
>> index 90978518e5f4..24a6e7e3d916 100644
>> --- a/drivers/dax/hmem/hmem.c
>> +++ b/drivers/dax/hmem/hmem.c
>> @@ -93,6 +93,40 @@ static void process_defer_work(struct work_struct *_work)
>>   	walk_hmem_resources(&pdev->dev, handle_deferred_cxl);
>>   }
>>   
>> +static void remove_soft_reserved(void *data)
>> +{
>> +	struct resource *r = data;
>> +
>> +	remove_resource(r);
> 
> Type doesn't really help us here so why not skip the local variable.
> 	remove_resource(data);
> 	kfree(data);
> 
> Though I'd rename data to r.
> 
>> +	kfree(r);

Fixed in v2.

>> +}
>> +
>> +static int add_soft_reserve_into_iomem(struct device *host,
>> +				       const struct resource *res)
>> +{
>> +	struct resource *soft = kzalloc(sizeof(*soft), GFP_KERNEL);
>> +	int rc;
>> +
>> +	if (!soft)
>> +		return -ENOMEM;
>> +
>> +	*soft = DEFINE_RES_NAMED_DESC(res->start, (res->end - res->start + 1),
>> +				      "Soft Reserved", IORESOURCE_MEM,
>> +				      IORES_DESC_SOFT_RESERVED);
>> +
>> +	rc = insert_resource(&iomem_resource, soft);
>> +	if (rc) {
>> +		kfree(soft);
> 
> Could use __free() magic here and steal the pointer when you setup the
> devm action below.  Only a small simplification in this case, so up to
> you.

Sure, I have incorporated.

> 
>> +		return rc;
>> +	}
>> +
>> +	rc = devm_add_action_or_reset(host, remove_soft_reserved, soft);
>> +	if (rc)
>> +		return rc;
>> +
>> +	return 0;
> 
> Trivial:
> 
> 	return dev_add_action_or_reset(host...)

Included.

Thanks,
Smita

> 
>> +}
>