linux-kernel - Re: [PATCH v11 06/10] genirq/msi-doorbell: msi_doorbell

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Message-ID: <20646d2e-b75f-b088-3ead-2aca039cde79@redhat.com>
Date:	Fri, 22 Jul 2016 16:08:57 +0200
From:	Auger Eric <eric.auger@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	eric.auger.pro@...il.com, marc.zyngier@....com,
	christoffer.dall@...aro.org, andre.przywara@....com,
	robin.murphy@....com, alex.williamson@...hat.com,
	will.deacon@....com, joro@...tes.org, jason@...edaemon.net,
	linux-arm-kernel@...ts.infradead.org, drjones@...hat.com,
	kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
	pbonzini@...hat.com, linux-kernel@...r.kernel.org,
	Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com,
	p.fedin@...sung.com, iommu@...ts.linux-foundation.org,
	Jean-Philippe.Brucker@....com, yehuday@...vell.com,
	Manish.Jaggi@...iumnetworks.com, robert.richter@...iumnetworks.com
Subject: Re: [PATCH v11 06/10] genirq/msi-doorbell: msi_doorbell_safe

Hi Thomas,
On 22/07/2016 14:44, Thomas Gleixner wrote:
> On Thu, 21 Jul 2016, Auger Eric wrote:
>> On 20/07/2016 10:12, Thomas Gleixner wrote:
>>> On Tue, 19 Jul 2016, Eric Auger wrote:
>>>> +bool msi_doorbell_safe(void)
>>>> +{
>>>> +	struct irqchip_doorbell *db;
>>>> +	bool irq_remapping = true;
>>>> +
>>>> +	mutex_lock(&irqchip_doorbell_mutex);
>>>> +	list_for_each_entry(db, &irqchip_doorbell_list, next) {
>>>> +		irq_remapping &= db->info.irq_remapping;
>>>
>>> db->info.irq_remapping is set in msi_doorbell_register(). So you can keep book
>>> about that there. No need to iterate here.
>> Yes makes sense to store the info at registration time. Currently this
>> function is not in any fast path but that's cleaner from a general
>> perspective. I will need to do such iteration at un-registration though.
> 
> Two simple counter should be sufficient.
> 
>   nr_registered_bells;
>   nr_remapped_bells;

Yes definitively smarter to use counters! mental viscosity.

Thanks

Eric
> 
> ....
> 
> Thanks,
> 
> 	tglx
>