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Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free routines

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On Wed, Jul 06, 2016 at 10:05:45AM +0200, Alexander Gordeev wrote:
> > + pci_enable_msi, pci_enable_msi_range, pci_enable_msi_exact, pci_disable_msi,
> > + pci_msi_vec_count, pci_enable_msix_range, pci_enable_msix_exact,
> > + pci_disable_msix, pci_msix_vec_count
> 
> Description of these functions can be removed when all drivers migrated
> to the new API. Also implementation descriptions + examples would still
> be needed AFAICT.

I diagreed - if we deprecated functions the only thing that should
be mentioned is a "don't use these". 

> This function's code almost matches the existing pci_enable_msix_range()
> so pci_enable_msix_range() should be reworked instead IMHO.

That's what earlier versions of the code did.  However due to the
fact that we want to avoid over-allocating the msix_vectors array
(minor) and get the vectors count of the affinity mask right (major,
as pointed out by you last time) I had to move the allocations inside
the helpers that loop around the atctual enablement.  I didn't want
to change the function to a different version of the algorithm just
before removing them relatively soon.  But given that strong preference
for changing these simple functions instead of duplicating them I've
changed that patch to do that now.

> We do not need to keep msix_entry array, since it only needed for
> pci_irq_vector() function. But the same info could be retrieved from
> msi_desc::irq.

Indeed.  Avoiding this allocation makes these interfaces quite a bit
simpler.  It requires a few prep patches, but I think it's definitively
worth, so the next version will avoid the need for the msix_entry array.

> > +	/* use legacy irq if allowed */
> > +	if (min_vecs == 1)
> > +		return 1;
> > +	return -ENOSPC;
> 
> The original error code (in vecs) would be overridden with -ENOSPC here.

Ok, fixed.

> > +	WARN_ON_ONCE(!dev->msi_enabled && nr > 0);
> > +	return dev->irq + nr;
> 
> I think this function should check irq number existence and return the
> vector number or -EINVAL;

Ok, fixed.

> > +		unsigned int flags)
> > +{
> > +	if (min_vecs > 1)
> > +		return -ENOSPC;
> 
> In case CONFIG_PCI_MSI is unset min_vecs > 1 is -EINVAL;

Ok, fixed.

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automatic interrupt affinity for MSI/MSI-X capable devices V3 Christoph Hellwig <hch@lst.de> - 2016-07-04 10:40 +0200
  [PATCH 04/13] irq: Use affinity hint in irqdesc allocation Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq: Use affinity hint in irqdesc allocation tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq: Introduce IRQD_AFFINITY_MANAGED flag tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  [PATCH 05/13] irq/msi: Make use of affinity aware allocations Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq/msi: Make use of affinity aware allocations tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  [PATCH 11/13] blk-mq: allow the driver to pass in an affinity mask Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
  [PATCH 13/13] nvme: remove the post_scan callout Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
  [PATCH 08/13] pci: spread interrupt vectors in pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    Re: [PATCH 08/13] pci: spread interrupt vectors in  pci_alloc_irq_vectors Alexander Gordeev <agordeev@redhat.com> - 2016-07-07 13:10 +0200
      Re: [PATCH 08/13] pci: spread interrupt vectors in  pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-07-10 06:00 +0200
        Re: [PATCH 08/13] pci: spread interrupt vectors in  pci_alloc_irq_vectors Alexander Gordeev <agordeev@redhat.com> - 2016-07-12 08:50 +0200
  [PATCH 01/13] irq/msi: Remove unused MSI_FLAG_IDENTITY_MAP Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq/msi: Remove unused MSI_FLAG_IDENTITY_MAP tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  [PATCH 12/13] nvme: switch to use pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    Re: [PATCH 12/13] nvme: switch to use pci_alloc_irq_vectors Alexander Gordeev <agordeev@redhat.com> - 2016-07-07 21:40 +0200
      Re: [PATCH 12/13] nvme: switch to use pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-07-10 06:00 +0200
  [PATCH 10/13] blk-mq: only allocate a single mq_map per tag_set Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
  [PATCH 09/13] blk-mq: don't redistribute hardware queues on a CPU hotplug event Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
  [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq: Add a helper to spread an affinity mask for  MSI/MSI-X vectors tip-bot for Christoph Hellwig <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  [PATCH 07/13] pci: Provide sensible irq vector alloc/free routines Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free  routines Alexander Gordeev <agordeev@redhat.com> - 2016-07-06 10:10 +0200
      Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free  routines Christoph Hellwig <hch@lst.de> - 2016-07-10 05:50 +0200
        Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free  routines Alexander Gordeev <agordeev@redhat.com> - 2016-07-11 12:40 +0200
          Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free  routines Christoph Hellwig <hch@lst.de> - 2016-07-12 11:20 +0200
            Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free  routines Alexander Gordeev <agordeev@redhat.com> - 2016-07-12 14:50 +0200
  [PATCH 03/13] irq: Add affinity hint to irq allocation Christoph Hellwig <hch@lst.de> - 2016-07-04 10:50 +0200
    [tip:irq/core] genirq: Add affinity hint to irq allocation tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-07-04 12:40 +0200
  Re: automatic interrupt affinity for MSI/MSI-X capable devices V3 Thomas Gleixner <tglx@linutronix.de> - 2016-07-04 12:40 +0200

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