linux-kernel - Re: [RFC v2 PATCH 07/14] irq: add a new generic IPI reservation code to irq core

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Message-ID: <561D1779.7060307@imgtec.com>
Date:	Tue, 13 Oct 2015 15:38:49 +0100
From:	Qais Yousef <qais.yousef@...tec.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	<linux-kernel@...r.kernel.org>, <jason@...edaemon.net>,
	<marc.zyngier@....com>, <jiang.liu@...ux.intel.com>,
	<ralf@...ux-mips.org>, <linux-mips@...ux-mips.org>
Subject: Re: [RFC v2 PATCH 07/14] irq: add a new generic IPI reservation code
 to irq core

On 10/13/2015 02:37 PM, Thomas Gleixner wrote:
> On Tue, 13 Oct 2015, Qais Yousef wrote:
>
>> +	if (domain == NULL)
>> +		domain = irq_default_domain; /* need a separate ipi_default_domain? */
> No tail comments please.
>
> We should neither use irq_default_domain nor have an
> ipi_default_domain.

OK though I understood that you were OK with using the irq_default_domain.

This means that arch code must parse the DT for an IPI domain. I think 
I've seen arch code using the root FDT to search for a specific node. 
I'll try to do something similar to search for an IPI domain.

>> +
>> +	virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
>> +	if (virq <= 0) {
>> +		pr_warn("Can't reserve IPI, failed to alloc descs\n");
>> +		return 0;
>> +	}
>> +
>> +	/* we are reusing hierarchy alloc function, should we create another one? */
>> +	virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
>> +					(void *) dest, true);
>> +	if (virq <= 0) {
>> +		pr_warn("Can't reserve IPI, failed to alloc irqs\n");
>> +		goto free_descs;
>> +	}
>> +
>> +	data = irq_get_irq_data(virq);
>> +	bitmap_copy(data->ipi_mask.cpumask, dest->cpumask, dest->nbits);
>> +	data->ipi_mask.nbits = dest->nbits;
> This does only initialize the first virq data. What about the others?

Right I missed that. I'll fix it.


>
>> +	return virq;
>> +
>> +free_descs:
>> +	irq_free_descs(virq, nr_irqs);
>> +	return 0;
>> +}
>> +
>> +/**
>> + * irq_destroy_ipi() - unreserve an IPI that was previously allocated
>> + * @irq: linux irq number to be destroyed
>> + *
>> + * Return an IPI allocated with irq_reserve_ipi() to the system.
> That wants to explain that it actually destroys a number of virqs not
> just the primary one.
>
>

OK I'll expand on that.

Thanks,
Qais
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