Re: [Intel-wired-lan] [PATCH net-next v2 4/8] net: napi: add CPU affinity to napi->config

[Ahmed Zaki <ahmed.zaki@intel.com>]

On 2024-12-19 8:42 p.m., Jakub Kicinski wrote:
> On Wed, 18 Dec 2024 09:58:39 -0700 Ahmed Zaki wrote:
>> +	if (!glue_created && flags & NAPIF_IRQ_AFFINITY) {
>> +		glue = kzalloc(sizeof(*glue), GFP_KERNEL);
>> +		if (!glue)
>> +			return;
>> +		glue->notify.notify = netif_irq_cpu_rmap_notify;
>> +		glue->notify.release = netif_napi_affinity_release;
>> +		glue->data = napi;
>> +		glue->rmap = NULL;
>> +		napi->irq_flags |= NAPIF_IRQ_NORMAP;
> 
> Why allocate the glue? is it not possible to add the fields:
> 
> 	struct irq_affinity_notify notify;
> 	u16 index;
> 
> to struct napi_struct ?

In the first branch of "if", the cb function netif_irq_cpu_rmap_notify() 
is also passed to irq_cpu_rmap_add() where the irq notifier is embedded 
in "struct irq_glue".

I think this cannot be changed as long as some drivers are directly 
calling irq_cpu_rmap_add() instead of the proposed API.