linux-kernel - Re: [PATCH v11 04/10] genirq/msi-doorbell: allow MSI doorbell (un)registration

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Date:	Wed, 20 Jul 2016 09:50:14 +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 04/10] genirq/msi-doorbell: allow MSI doorbell
 (un)registration

Hi Thomas,
On 19/07/2016 16:22, Thomas Gleixner wrote:
> On Tue, 19 Jul 2016, Eric Auger wrote:
>> +
>> +#include <linux/slab.h>
>> +#include <linux/irq.h>
>> +#include <linux/msi-doorbell.h>
>> +
>> +struct irqchip_doorbell {
>> +	struct irq_chip_msi_doorbell_info info;
>> +	struct list_head next;
> 
> Again, please align the struct members.
> 
>> +};
>> +
>> +static LIST_HEAD(irqchip_doorbell_list);
>> +static DEFINE_MUTEX(irqchip_doorbell_mutex);
>> +
>> +struct irq_chip_msi_doorbell_info *
>> +msi_doorbell_register_global(phys_addr_t base, size_t size,
>> +			     int prot, bool irq_remapping)
>> +{
>> +	struct irqchip_doorbell *db;
>> +
>> +	db = kmalloc(sizeof(*db), GFP_KERNEL);
>> +	if (!db)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	db->info.doorbell_is_percpu = false;
> 
> Please use kzalloc and get rid of zero initialization. If you add stuff to the
> struct then initialization will be automatically 0.
OK
> 
>> +void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *dbinfo)
>> +{
>> +	struct irqchip_doorbell *db, *tmp;
>> +
>> +	mutex_lock(&irqchip_doorbell_mutex);
>> +	list_for_each_entry_safe(db, tmp, &irqchip_doorbell_list, next) {
> 
> Why do you need that iterator? 
> 
>     db = container_of(dbinfo, struct ....., info);
> 
> Hmm?

definitively
> 
>> +		if (dbinfo == &db->info) {
>> +			list_del(&db->next);
>> +			kfree(db);
> 
> Please move the kfree() outside of the lock region. It does not matter much
> here, but we really should stop doing random crap in locked regions.
OK

Thanks

Eric
> 
> Thanks,
> 
> 	tglx
>