Re: [PATCH v2 1/3] PCI/MSI: Add Devres managed IRQ vectors allocation

[Shawn Lin <shawn.lin@rock-chips.com>]

Hi Frank

在 2026/04/17 星期五 14:10, Frank Li 写道:
> On Fri, Apr 17, 2026 at 10:26:05AM +0800, Shawn Lin wrote:
>> pcim_alloc_irq_vectors() and pcim_alloc_irq_vectors_affinity() are created for
>> pci device drivers which rely on the devres machinery to help cleanup the IRQ
>> vectors.
>>
>> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>>
>> ---
>>
>> Changes in v2: None
>>
>>   drivers/pci/msi/api.c | 26 ++++++++++++++++++++++++++
>>   include/linux/pci.h   | 22 ++++++++++++++++++++++
>>   2 files changed, 48 insertions(+)
>>
> ...
>> +/**
>> + * pcim_alloc_irq_vectors_affinity() - devres managed pci_alloc_irq_vectors_affinity()
>> + * Interrupt vectors are automatically freed by the devres machinery
>> + */
>> +int pcim_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>> +				   unsigned int max_vecs, unsigned int flags,
>> +				   struct irq_affinity *affd)
>> +{
>> +	dev->is_msi_managed = true;
>> +	return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs,
>> +					      flags, affd);
> 
> any side effect if pci_alloc_irq_vectors_affinity() return fail and
> is_msi_managed keep true.

Thanks for the review! This is a good point.

You're absolutely right that in the current implementation, if
pci_alloc_irq_vectors_affinity() fails, is_msi_managed remains true
while no vectors are actually allocated.

This replicates the behavior of pcim_enable_device() +
pci_alloc_irq_vectors_affinity() , which also sets
is_msi_managed unconditionally, but that doesn't make it ideal.

I think we should fix this for better self-contained behavior. The
pcim_* APIs should be robust on their own.

I'll move the is_msi_managed assignment to after successful allocation
in v3, if the general apporach looks feasible.


> 
> Frank
>>
> 
>