linux-kernel - Re: [patch 22/39] PCI/MSI: Move pci_alloc_irq

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Date:   Wed, 16 Nov 2022 10:22:10 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        "Ahmed S. Darwish" <darwi@...utronix.de>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [patch 22/39] PCI/MSI: Move pci_alloc_irq_vectors() to api.c

On Fri, Nov 11, 2022 at 02:54:50PM +0100, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <darwi@...utronix.de>
> 
> To distangle the maze in msi.c, all exported device-driver MSI APIs are
> now to be grouped in one file, api.c.
> 
> Make pci_alloc_irq_vectors() a real function instead of wrapper and add
> proper kernel doc to it.
> 
> Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

Two nits below.

> ---
>  drivers/pci/msi/api.c | 33 +++++++++++++++++++++++++++++++++
>  include/linux/pci.h   | 17 +++++++++--------
>  2 files changed, 42 insertions(+), 8 deletions(-)
> ---
> diff --git a/drivers/pci/msi/api.c b/drivers/pci/msi/api.c
> index d48050555d55..1714905943fb 100644
> --- a/drivers/pci/msi/api.c
> +++ b/drivers/pci/msi/api.c
> @@ -90,3 +90,36 @@ int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
>  	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
>  }
>  EXPORT_SYMBOL(pci_enable_msix_range);
> +
> +/**
> + * pci_alloc_irq_vectors() - Allocate multiple device interrupt vectors
> + * @dev:      the PCI device to operate on
> + * @min_vecs: minimum required number of vectors (must be >= 1)
> + * @max_vecs: maximum desired number of vectors
> + * @flags:    One or more of:
> + *            %PCI_IRQ_MSIX      Allow trying MSI-X vector allocations
> + *            %PCI_IRQ_MSI       Allow trying MSI vector allocations
> + *            %PCI_IRQ_LEGACY    Allow trying legacy INTx interrupts, if
> + *                               and only if @min_vecs == 1
> + *            %PCI_IRQ_AFFINITY  Auto-manage IRQs affinity by spreading
> + *                               the vectors around available CPUs
> + *
> + * Allocate up to @max_vecs interrupt vectors on device. MSI-X irq

s/irq/IRQ/

> + * vector allocation has a higher precedence over plain MSI, which has a
> + * higher precedence over legacy INTx emulation.
> + *
> + * Upon a successful allocation, the caller should use pci_irq_vector()
> + * to get the Linux IRQ number to be passed to request_threaded_irq().
> + * The driver must call pci_free_irq_vectors() on cleanup.
> + *
> + * Return: number of allocated vectors (which might be smaller than
> + * @max_vecs), -ENOSPC if less than @min_vecs interrupt vectors are

s/less/fewer/ (also in some previous patches, IIRC)

> + * available, other errnos otherwise.
> + */
> +int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> +			  unsigned int max_vecs, unsigned int flags)
> +{
> +	return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs,
> +					      flags, NULL);
> +}
> +EXPORT_SYMBOL(pci_alloc_irq_vectors);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 2bda4a4e47e8..6a356a39ba94 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1553,6 +1553,8 @@ static inline int pci_enable_msix_exact(struct pci_dev *dev,
>  		return rc;
>  	return 0;
>  }
> +int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> +			  unsigned int max_vecs, unsigned int flags);
>  int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>  				   unsigned int max_vecs, unsigned int flags,
>  				   struct irq_affinity *affd);
> @@ -1586,6 +1588,13 @@ pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>  		return 1;
>  	return -ENOSPC;
>  }
> +static inline int
> +pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> +		      unsigned int max_vecs, unsigned int flags)
> +{
> +	return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs,
> +					      flags, NULL);
> +}
>  
>  static inline void pci_free_irq_vectors(struct pci_dev *dev)
>  {
> @@ -1900,14 +1909,6 @@ pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>  }
>  #endif /* CONFIG_PCI */
>  
> -static inline int
> -pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> -		      unsigned int max_vecs, unsigned int flags)
> -{
> -	return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs, flags,
> -					      NULL);
> -}
> -
>  /* Include architecture-dependent settings and functions */
>  
>  #include <asm/pci.h>
>