linux-kernel - Re: [PATCH v4 1/2] PCI: Add tango MSI controller support

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Message-ID: <4885137f-7c1c-5742-4f66-f48c32ce7abb@free.fr>
Date:   Wed, 31 May 2017 20:49:04 +0200
From:   Mason <slash.tmp@...e.fr>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Robin Murphy <robin.murphy@....com>,
        Marc Gonzalez <marc_gonzalez@...madesigns.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        David Laight <david.laight@...lab.com>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] PCI: Add tango MSI controller support

On 31/05/2017 19:34, Bjorn Helgaas wrote:
> On Wed, May 31, 2017 at 04:18:44PM +0200, Mason wrote:
>
>> For the record, below is the patch I had in mind:
>>
>> diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
>> index 8a3e872798f3..edfc95575a37 100644
>> --- a/kernel/irq/msi.c
>> +++ b/kernel/irq/msi.c
>> @@ -91,9 +91,11 @@ int msi_domain_set_affinity(struct irq_data *irq_data,
>>  {
>>         struct irq_data *parent = irq_data->parent_data;
>>         struct msi_msg msg;
>> -       int ret;
>> +       int ret = -EINVAL;
>> +
>> +       if (parent->chip->irq_set_affinity)
>> +               ret = parent->chip->irq_set_affinity(parent, mask, force);
>>  
>> -       ret = parent->chip->irq_set_affinity(parent, mask, force);
>>         if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE) {
>>                 BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
>>                 irq_chip_write_msi_msg(irq_data, &msg);
>>
>>
>>
>> Then, it would be safe to remove "do-nothing" .irq_set_affinity
>> callbacks in drivers/pci/host
> 
> I assume it's obvious that nobody else is going to take this and run
> with it, so nothing will happen with this unless you finish it up by
> doing the cleanup (removing the "do-nothing" callbacks) and adding a
> changelog and signed-off-by.

Smirk.

> This would be more an IRQ patch than a PCI patch, but if I were
> reviewing it, I would look for assurance that *all* the no-op
> .irq_set_affinity callbacks were cleaned up, not just those in
> drivers/pci/host.

Are you saying the patch is *wrong* if not all "do-nothing"
callbacks are cleaned up?

Regards.