Re: [PATCH v3] interconnect: avoid memory allocation when 'icc_bw_lock' is held

[Gabor Juhos]

2025. 06. 25. 14:41 keltezéssel, Johan Hovold írta:
> On Wed, Jun 25, 2025 at 02:30:15PM +0200, Johan Hovold wrote:
>> On Wed, Jun 25, 2025 at 01:25:04PM +0200, Gabor Juhos wrote:
> 
>>> @@ -276,13 +276,17 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>>>  		qcom_icc_bcm_init(qp->bcms[i], dev);
>>>  
>>>  	for (i = 0; i < num_nodes; i++) {
>>> +		bool is_dyn_node = false;
>>> +
>>>  		qn = qnodes[i];
>>>  		if (!qn)
>>>  			continue;
>>>  
>>>  		if (desc->alloc_dyn_id) {
>>> -			if (!qn->node)
>>> +			if (!qn->node) {
>>
>> AFAICS, qn->node will currently never be set here and I'm not sure why
>> commit 7f9560a3bebe ("interconnect: qcom: icc-rpmh: Add dynamic icc node
>> id support") added this check, or even the node field to struct
>> qcom_icc_desc for that matter.
>>
>> But if there's some future use case for this, then you may or may not
>> need to make sure that a name is allocated also in that case.
> 
> Ok, I see what's going on. The qn->node may have been (pre-) allocated
> in icc_link_nodes() dynamically, which means you need to make sure to
> generate a name also in that case.
> 
>> And that could be done by simply checking if node->id >=
>> ICC_DYN_ID_START instead of using a boolean flag below. That may be
>> preferred either way.
> 
> So you should probably use node->id to determine this.

You are right. The problem is that ICC_DYN_ID_START is only visible from the
core code. Either we have to move that into the 'interconnect-provider.h' header
or we have to add an icc_node_is_dynamic() helper or something similar.

Which is the preferred solution?

Regards,
Gabor